Renal cyst in children: clinical guidelines

Applies tochildren2026 editionN28.1, Q61.0

Clinical Guidelines of the Russian Ministry of Health, pediatric. 2026 edition, ICD-10 codes: N28.1, Q61.0.

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Brief for Practice

WhiteCoat Pro editorial summary of the guideline text, 2026 edition. Each point links to the original section — verify with it before prescribing.

A simple renal cyst in children is a rounded, thin-walled fluid-filled lesion within/outside the parenchyma, not communicating with the collecting system and not associated with a systemic disease. In children, a simple cyst is a diagnosis of exclusion: it is important to differentiate it from hereditary cystic diseases, caliceal diverticulum, dysplasia, and neoplastic processes; monitoring is usually required rather than treatment.

Key points

Diagnostics

  1. Collection of complaints and medical history is performed; family history is checked for ADPKD/polycystic kidney disease, as well as early hypertension or early stroke in parents and relatives. LoE C, GoE 5. → in text
  2. Physical examination: height, blood pressure, signs of decreased renal function, edema, skin color, palpable mass, manifestations of hereditary syndromes; assess for multiplicity/bilaterality of cysts and congenital anomalies. LoE C, GoE 5. → in text
  3. Laboratory tests: complete blood count, urinalysis, blood creatinine and urea; acid-base status and blood gases if metabolic acidosis is suspected. LoE C, GoE 5. → in text
  4. Atypical abnormalities for a simple cyst: anemia, proteinuria, elevated creatinine, metabolic acidosis; these require screening for another renal disease. Hematuria and leukocyturia may occur in case of cyst rupture or infection. → in text
  5. The primary imaging method is ultrasound of the kidneys and urinary tract ± Doppler ultrasound: a simple cyst is thin-walled (<1 mm), with homogeneous content, without septa, calcifications, solid components, connection to the pelvicalyceal system, or blood flow. LoE C, GoE 5. → in text
  6. To differentiate from a caliceal diverticulum, contrast-enhanced CT of the kidneys and upper urinary tract with intravenous bolus administration and delayed scans no earlier than 20 minutes is used; a simple cyst does not enhance, whereas contrast in the cavity indicates communication with the collecting system. LoE C, GoE 4. → in text
  7. Contrast-enhanced renal MRI is not performed routinely for a typical simple cyst; indications: large cysts in young children, pronounced symptoms, hematuria, suspected tumor, tuberous sclerosis, assessment of kidney size in ADPKD, differentiation from caliceal diverticulum, insufficient diagnostic value or unavailability of CT. LoE C, GoE 5. → in text

Treatment

When to refer and how to monitor

Frequently asked questions

What renal cyst in a child is considered simple?

This is a rounded, thin-walled, anechoic lesion with homogeneous content, without septa, calcifications, echogenic/solid inclusions, blood flow, or communication with the renal collecting system. → in text

Should an asymptomatic simple renal cyst be treated?

Usually no: conservative treatment of a solitary cyst is not performed, and dynamic observation is chosen for an asymptomatic course. Ultrasound findings, symptoms, blood pressure, and renal function are monitored. → in text

When is surgery needed for a renal cyst in a child?

Surgery is considered for rapid growth, hematuria, arterial hypertension, pain, infection, suspected tumor, as well as for cysts >3 cm, rapid growth, or size >30% of the kidney size. → in text

How frequently should a child with a simple renal cyst be monitored?

Examination with blood pressure measurement is performed on average annually, or more frequently if necessary. Ultrasound of the kidneys and urinary tract is performed annually for 5 years and/or until the age of 15. → in text

When is genetic testing necessary for a solitary cyst?

In the case of a single simple cyst and unconfirmed renal disease, genetic screening is not recommended. Molecular genetic testing is indicated when symptoms are present or the number of cysts increases on serial imaging; the scope is determined by the geneticist. → in text

Status
Applied · approved by the Scientific and Practical Council of the Russian Ministry of Health
Database ID
836, version 2 (ID 836_2)
Publication date
October 9, 2026
Age category
children
ICD-10 codes
N28.1Q61.0
Specialties
PediatricsMedical GeneticsUrology
Developers
Union of Pediatricians of Russia
Association of Medical Geneticists
Association of Pediatric Urologists-Andrologists
All-Russian Public Organization "Russian Association of Pediatric Urologists-Andrologists"
Official text
Ministry of Health of Russia Rubricator — 836_2

List of Abbreviations

AH – arterial hypertension

BP – blood pressure

ADPKD – autosomal dominant polycystic kidney disease

ADT – autosomal dominant type

ALT – alanine aminotransferase

ARPKD – autosomal recessive polycystic kidney disease

ART – autosomal recessive type

AST – aspartate aminotransferase

ARB – angiotensin II receptor blocker (angiotensin receptor blocker, ATC: C09C)

ACEI – angiotensin-converting enzyme (ACE) inhibitor (ATC: C09A)

UTI – urinary tract infection

EIA – enzyme immunoassay

CKD – cystic kidney disease

CT – computed tomography

UT – urinary tract

ICD – International Classification of Diseases

INR – international normalized ratio

MRI – magnetic resonance imaging

MSCT – multislice computed tomography

PT – prothrombin time

SRKC – simple renal cortical cysts

GFR – glomerular filtration rate

ESRD – end-stage renal disease

US – ultrasound examination

CKD – chronic kidney disease

ECG – electrocardiogram

EchoCG – echocardiography

CAKUT – congenital anomalies of the kidney and urinary tract

K/DOQI – Kidney Disease Outcomes Quality Initiative – Clinical Practice Guidelines for Chronic Kidney Disease

Terms and Definitions

Specific terms and definitions are not applied.

1. Brief information on the disease or condition

1.1 Definition of the disease or condition

Cystic kidney disease is a renal disorder characterized by the presence of cysts within the renal parenchyma, separated by both the renal tissue itself and connective tissue layers.

A simple renal cyst (SRC) is a rounded, fluid-filled formation located outside and/or within the renal parenchyma, with a smooth surface, homogeneous content, devoid of calcifications and other echogenic foci within its structure, not communicating with the collecting system of the kidney, and not associated with systemic diseases (e.g., polycystic kidney disease) [1, 2].

1.2 Etiology and pathogenesis of the disease or condition (group of diseases or conditions)

Simple renal cysts are typically unilateral and solitary lesions, and their pathogenesis remains not fully understood. It is known that the development of cystic anomalies is associated with deviations in embryogenesis during the first weeks of intrauterine life. At this stage, various deviations from normal embryonic development are possible. With very rapid growth, one of the primary calyces can separate from the main metanephric duct and transform into an isolated cavity. This is how parapelvic cysts arise. If fusion of the primary renal tubules with the collecting tubule buds does not occur, while the rest of the nephron forms normally and even begins to function, then having no outlet into the urinary tract, it expands and turns into a typical retention cyst. Cysts are predominantly localized initially in the cortical layer of the kidneys and never communicate with the lower outflow ducts.

The etiology and pathogenesis of simple renal cysts in children are not definitively known. A possible, but currently unproven, explanation for the appearance of simple renal cysts is the obstruction of renal tubules or caliceal diverticula [3].

The fact of an increasing detection rate of simple renal cysts with age is well established.

Renal cysts may manifest as a focal disease (simple and complex renal cysts), affect the entire kidney (e.g., multicystic dysplastic kidney (MCDK) or cystic dysplasia), or present as bilateral cystic disease (e.g., autosomal recessive polycystic kidney disease (ARPKD) or autosomal dominant polycystic kidney disease (ADPKD)).

In children, unlike adults, a large proportion of renal cysts are due to genetic diseases (e.g., HNF1B-associated nephropathy, various ciliopathies, and tuberous sclerosis), and a smaller number of patients have simple cysts or acquired cystic kidney disease.

1.3 Epidemiology of the Disease or Condition

Simple renal cysts (SRCs) are relatively rare in childhood (particularly rare at birth and in infancy), being detected in a small percentage of cases (prevalence 0.2% – 2%), with incidence increasing with age: 0.22% in children, up to 20% in 40-year-old patients, and up to 33% in individuals over 60 [1, 62].

A simple renal cyst is most often discovered incidentally when an imaging study is performed (usually a comprehensive abdominal ultrasound A04.16.001 or renal ultrasound, less commonly abdominal magnetic resonance imaging, abdominal computed tomography, etc.) routinely or for some indications (routine prenatal examinations or as part of preventive check-ups, as well as for abdominal pain, suspected urinary tract infection, etc.). About 25% of these cysts are diagnosed prenatally or during the first year of life [3].

The prevalence of simple cysts in the pediatric population, according to various sources, ranges from 0.22 to 1% (case series descriptions in cohorts of over 10,000 children) [4, 5, 6, 7].

The true prevalence may be either higher or lower, as studies standardizing approaches to indications for renal ultrasound and technical aspects have not been conducted [1]. Studies in adults indicate that the incidental detection rate of simple cysts on computed tomography or magnetic resonance imaging is higher than with ultrasound [8].

A characteristic feature of simple cysts is an increase in their frequency of occurrence with age. Thus, the prevalence of simple cysts in the adult population, according to various authors, ranges from 4% to 41% [9, 10].

There are several differences in the clinical course of the disease between children and adults. The main risk factor in adults is cystic renal cell carcinoma (RCC) [63, 64, 65]. Malignant transformation of renal cysts into renal cell carcinoma, Wilms tumor, or multilocular cystic renal cell carcinoma in children is extremely rare [65, 66, 67].

1.4 Features of Coding the Disease or Condition

Q61.0 Congenital single renal cyst

N28.1 Renal cyst

1.5 Classification of the disease or condition

Cysts originating from renal tissue are diverse, so it is very important to understand which group of cysts we are dealing with. Professor Morton A. Bosniak made a huge contribution to the creation of the classification of renal cysts. In 1986, he proposed a classification of renal cysts, subsequently named after him, based on computed tomography data and allowing the prediction of the likelihood of a malignant process within them. Over the course of its existence, the classification has undergone changes and revisions. The latest revision of the classification was in 2019 and was supplemented with magnetic resonance imaging data [11].

Bosniak Classification of Renal Cysts

According to the classification, cysts are divided into 5 groups:

I, II, IIF, III, and IV.

Bosniak Category I Renal Cysts

Features of Category I cysts on CT:

1) Thin wall (≤ 2 mm).

2) Fluid content inside.

3) No septa, calcium deposits, or tissue nodules inside the cyst.

4) The cyst wall may show minimal contrast enhancement.

Features of Category I cysts on MRI:

1) Thin wall (≤ 2 mm).

2) Homogeneous fluid content (signal intensity similar to that of cerebrospinal fluid).

3) No septa or evidence of calcium salt deposition.

4) The cyst wall may enhance with paramagnetic contrast agent.

Bosniak Category II Renal Cysts

Features of Category II cysts on CT:

1) Few (fewer than three) thin septa, less than 2 millimeters in thickness.

2) The septum and wall may enhance with contrast and contain calcium salt deposits.

Features of Category II cysts on MRI:

This category includes three types of thin-walled cysts (< 2 mm):

1) Cysts with a small number (1–3) of contrast-enhancing septa, or non-enhancing septa but with evidence of calcium salt deposition.

2) Cysts with homogeneous content showing marked high signal intensity on T2-weighted (T2W) images (similar to cerebrospinal fluid) on unenhanced MRI.

3) Cysts with homogeneous content showing marked high signal intensity on T1-weighted (T1W) images (approximately 2.5 times higher than normal parenchymal signal intensity) on unenhanced MRI.

Bosniak Category IIF Renal Cysts

Features of Category IIF cysts on CT:

1) Cyst wall thickness of 3 mm with contrast enhancement.

2) Presence of multiple (more than 4) septa with a wall thickness of less than 2 millimeters, showing contrast enhancement.

Features of Category IIF cysts on MRI:

This category includes two types of cysts:

1) Cysts with a wall or septal thickness of 3 mm with contrast enhancement, or multiple (≥ 4) smooth, thin (≤ 2 mm) contrast-enhancing septa.

2) Cysts that show focal areas of high signal intensity on unenhanced T1-weighted fat-saturated MRI.

Bosniak Category III Cystic Renal Lesion

Features of Category III cysts on CT:

1) Cyst wall or septa thicker than 4 millimeters, showing contrast enhancement.

2) Wall or septa thickness less than 3 mm, but with an obtuse angle of tissue protrusion into the cyst lumen.

MRI characteristics of category 3 cysts:

1) One or more cyst walls > 4 mm in thickness.

2) Enhancement of irregular or thickened areas, or a convex protrusion with smooth/blunt margins ≤ 3 mm.

Bosniak category IV cystic renal lesions

CT characteristics of category 4 cysts:

1) Cystic renal lesion with tissue nodules > 4 mm and a convex protrusion with obtuse angles.

2) Nodules of any thickness showing contrast enhancement and acute angles.

MRI characteristic of category 4 cysts:

1) One or more contrast-enhancing tissue nodules.

2) A convex protrusion ≥ 4 mm with blunt margins or a convex protrusion of any size with acute angles.

1.6 Clinical presentation of the disease or condition

Simple renal cysts are typically incidental findings and can be diagnosed via ultrasound both prenatally and postnatally. Cysts with additional features such as solid components, septa, or thickened walls should be considered complex cysts.

In most cases, simple renal cysts are asymptomatic. However, they may occasionally present with clinical manifestations:

- causing pain (in large cysts) due to compression of adjacent organs;

- causing spontaneous hematuria;

- becoming infected and/or suppurating, leading to acute inflammation;

- causing arterial hypertension;

- causing urinary tract infections;

- being palpable as an abdominal mass [12,13,14].

Simple cysts may be diagnosed in utero and subsequently undergo involution even before birth [15].

Clinical symptoms usually arise from complications of cystic renal disease: hemorrhage, cyst rupture, infection, or suppuration.

Sometimes the sole symptom of a simple renal cyst is asymptomatic hematuria [16].

Natural history studies of prenatally detected "simple" cysts indicate that some of these lesions, particularly those > 20 mm in diameter in the prenatal period, require careful follow-up. A solitary cyst in a normal kidney may be the initial manifestation of polycystic kidney disease or, rarely, a malignancy. Conversely, it may be a "simple" self-resolving lesion or an asymptomatic finding requiring no medical intervention [17,18].

Differential diagnosis includes other cystic diseases (a solitary cyst may be the initial manifestation of genetic cystic renal disease or, rarely, a malignant neoplasm), caliceal diverticula, hydrocalycosis, cystic dysplasias, and—very rarely—echinococcal cysts [19].

Differential diagnosis is presented in Section 2.5.1.

A child with a newly diagnosed unilateral renal cyst requires a detailed medical and family history, a thorough clinical examination, and at least one follow-up imaging study. Therefore, simple cysts should be considered a diagnosis of exclusion.

Proteinuria in simple congenital cysts is 10.1%, arterial hypertension 7.4%, and decreased renal function 8.4%. The level of evidence in the literature is low, with only 11% of studies containing large patient cohorts [68].

2. Diagnostics, medical indications and contraindications for diagnostic methods

The diagnostic criterion for a simple renal cyst is the detection on ultrasound (renal ultrasound, duplex scanning of renal arteries) of a unilateral, round, thin-walled, anechoic lesion without septa, not communicating with the collecting system and lacking blood flow [7,18].

Following contrast-enhanced computed tomography (CT) of the kidneys and upper urinary tracts with intravenous bolus administration and Hounsfield unit density measurements of the fluid content to rule out communication with the collecting system, performed alongside delayed excretory urograms (contrast-enhanced CT of the kidneys and upper urinary tracts) or contrast-enhanced MRI of the kidneys, it is possible to differentiate a simple renal cyst from a caliceal diverticulum and determine its exact anatomical location.

Since simple cysts are relatively rare in children, their detection may be a harbinger of an underlying condition (polycystic kidney disease, renal malignancy) [20].

Therefore, initial evaluation of a child with an identified simple cyst requires differential diagnosis with other cystic renal lesions, treating the simple cyst as a diagnosis of exclusion [18].

During the initial evaluation of a child with a simple solitary cyst, a number of clinical findings must be taken into account (multiple cysts, bilateral renal cysts, congenital anomalies including urogenital anomalies, other structural urogenital disorders, arterial hypertension, urinalysis abnormalities), along with history data (family history of cystic renal diseases) and complaints (flank pain, abdominal pain). All of these may indicate a diagnosis other than a simple solitary cyst.

2.1 Complaints and Anamnesis

It is recommended that children with a renal cyst identified by renal ultrasound (or other imaging methods) / suspected renal cyst undergo collection of anamnestic data and complaints regarding renal and urinary tract pathology (as part of an initial or follow-up consultation/examination by a pediatric urologist-androloist, pediatric surgeon, pediatrician, and/or nephrologist) for diagnostic purposes [1].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comments: for details, see Section 1.6.

Because a solitary simple renal cyst may be the initial manifestation of a genetic disorder, it is necessary to clarify the family history regarding ADPKD/polycystic kidney disease.

The most frequent hereditary disorder leading to cyst progression and subsequent chronic kidney disease is autosomal dominant polycystic kidney disease (ADPKD) [21]. However, in some cases, a parent with ADPKD may be unaware of their condition. Therefore, family history taking must include screening the parents for early-onset hypertension or a family history of early stroke as a consequence of cerebral aneurysms.

Rarer hereditary disorders leading to cyst formation include tuberous sclerosis, Bardet-Biedl syndrome, Beckwith-Wiedemann syndrome, juvenile nephronophthisis, etc. [22].

2.2 Physical Examination

It is recommended that children with a renal cyst identified by renal ultrasound (or other imaging methods) / suspected renal cyst undergo a physical examination focusing on renal and urinary tract pathology, including visual inspection, palpation, auscultation, height measurement, and peripheral blood pressure measurement (as part of an initial or follow-up consultation/examination by a pediatric urologist-andrologist, pediatric surgeon, pediatrician, and/or nephrologist) for diagnostic purposes [1].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comment: physical examination should focus on signs of decreased renal function (skin pallor, edema, elevated blood pressure, etc.), as well as manifestations of hereditary disorders, such as polydactyly in Bardet-Biedl syndrome, angiokeratomas in tuberous sclerosis, etc. [23]. If sufficiently large, the cyst may be palpable as an abdominal mass.

Abdominal and retroperitoneal examination should begin with superficial palpation. Palpation of the renal areas (palpation for renal and urinary tract pathology) is performed with the patient in the supine and/or lateral position, as well as standing. Examination may reveal tenderness in the lumbar and abdominal regions, and palpation of a "mass-like" lesion (in large renal cysts). Tenderness during the examination indicates possible compression of adjacent organs by the cyst or upper urinary tract obstruction.

It is recommended that children with a newly diagnosed renal cyst, even in the absence of a known family history of cysts, be thoroughly examined for the following clinical signs indicating a genetic/congenital etiology:

- growth abnormalities, elevated blood pressure, urinalysis abnormalities;

- multiple cysts and/or bilateral localization;

- kidney size (enlarged or small kidney);

- renal echogenicity;

- presence of signs of congenital anomalies of the kidney and urinary tract (vesicoureteral reflux, pelviureteric junction obstruction);

- presence of symptoms such as urinary tract infection, gross hematuria, etc. for differential diagnosis [1].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

2.3 Laboratory Diagnostics

It is recommended to perform a complete blood count in children with a detected simple renal cyst for early differential diagnosis with kidney diseases associated with cyst formation and to identify associated abnormalities [1,24, 25].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comment: the presence of changes in the complete blood count characteristic of anemia is more indicative of hereditary cystic kidney diseases [1,24,25].

It is recommended to perform a urinalysis for diagnostic purposes in children with a simple renal cyst [1,24,25].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comment: according to available data, the majority of patients (84%) with a simple renal cyst have no abnormalities in the urinalysis [12].

The presence of proteinuria in the general urinalysis indicates the need for further diagnostic investigation, since proteinuria is typically not characteristic of patients with a simple solitary renal cyst [1,4,12,24,25].

At the same time, hematuria may also occur in patients with a diagnosed simple renal cyst, including gross hematuria in the event of renal cyst rupture [7,12].

In simple cysts complicated by a urinary tract infection, leukocyturia may be detected [7,12].

It is recommended to determine blood creatinine and blood urea levels for diagnostic purposes in children with a simple renal cyst to clarify the presence of signs of decreased renal function [1,12,24,25,69].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comment: an elevated serum creatinine level is not typical for patients with a simple renal cyst and indicates the presence of another chronic kidney disease [1,12].

It is recommended for children with a simple renal cyst to undergo an acid-base balance and blood gas analysis during the initial examination for the timely diagnosis of metabolic acidosis (if this condition is suspected) [1].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comment: metabolic acidosis indicates the presence of chronic kidney disease, as it is not characteristic of a simple renal cyst [1].

Indications for other laboratory tests are determined by the list of diseases with which differential diagnosis is carried out.

2.4 Instrumental Diagnostics

As noted earlier, in children, renal cysts are usually incidental findings during ultrasound examination or are diagnosed during targeted examination when the child develops symptoms (abdominal or flank pain, palpation of an abdominal mass, signs of urinary tract infection, hematuria).

A simple renal cyst can be detected both prenatally and postnatally in a child of any age.

In a fetus, a renal cyst can be diagnosed using fetal ultrasonography as early as 14–16 weeks of gestation. Accordingly, during routine fetal ultrasound examination, attention should be paid to the state of the kidneys for the timely diagnosis of a cystic mass [26]. When visualizing the fetal kidneys, suspicion of a cyst may be raised by their enlargement and/or hyperechogenicity. Oligohydramnios, decreased lung volume, and other extrarenal manifestations point to a congenital pathology [18].

It is recommended to perform a renal ultrasound, urinary tract ultrasound, and/or urinary tract ultrasound with color Doppler flow imaging (duplex scanning of renal arteries) for diagnostic purposes in patients with suspected renal cyst or with a previously detected simple renal cyst [1,12,18,24,25].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comments: on ultrasound, a simple cyst appears as a round, smooth, thin-walled (< 1 mm) structure with homogeneous contents. Septations, calcifications, echogenic inclusions, or solid components are not characteristic. A simple cyst is not connected to the renal collecting system and shows no blood flow.

Simple cysts can be diagnosed anywhere in the parenchyma, but they are most frequently visualized in the upper pole of the right kidney, and the contralateral kidney is usually intact [1,12,18,27,28].

Kidney dimensions obtained during the examination are compared with reference values. The detected cyst is examined for signs of hemorrhage, infection, or malignancy, the signs of which include calcification, wall thickening, presence of septations, echogenic inclusions within the cyst, as well as increased blood flow in the septa and the walls of the cyst itself [18].

For better visualization, the following can be used: a convex transducer with a frequency > 7 MHz (in the supine position - transducer on the flank) and a linear transducer with a frequency > 10 MHz (in the prone position - transducer on the back). A low-frequency transducer may be required for older or obese children [18].

It is recommended to perform computed tomography of the kidneys and upper urinary tracts with intravenous bolus contrast enhancement and delayed scans in the excretory phase (excretory urography [intravenous urography]) for differential diagnosis with caliceal diverticula in patients with suspected renal cyst or with a previously detected simple renal cyst [14,29,30,31,32].

GRC CLEL 4Grade of Recommendation C (Level of Evidence – 4)

Comments: this allows obtaining complete information about the state of the renal parenchyma and upper urinary tracts, the location and shape of cysts, identifying/excluding communication between the cyst and the renal collecting system, their relationship with the pelvicaliceal system and major vessels, and indirectly assessing the contents of the cyst cavity [29].

Delayed tomograms should be performed no earlier than 20 minutes after contrast administration. On delayed tomograms, a simple renal cyst does not enhance. However, the presence of contrast medium within the cystic cavity indicates communication with the renal collecting system and can be regarded as a caliceal diverticulum [33].

It is recommended that when a patient is found to have a simple cyst exceeding 2.5 cm in size, further evaluation be performed (genetic testing for primary and other genes causing cystic diseases [initial and follow-up consultations with a geneticist], computed tomography of the kidneys and upper urinary tracts with intravenous bolus contrast enhancement, or contrast-enhanced magnetic resonance imaging [MRI] of the kidneys) to rule out or confirm a diagnosis of autosomal dominant polycystic kidney disease (ADPKD), even despite the absence of a family history of this disease [34,77].

GRC CLEL 4Grade of Recommendation C (Level of Evidence – 4)

Comments: it has been shown that when the cyst size exceeds 2.5 cm, the probability of diagnosing ADPKD is 75% [34].

It is recommended to perform a comprehensive abdominal ultrasound in children with a detected simple renal cyst to identify extrarenal signs characteristic of other cystic renal diseases [23,35].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comment: during the examination, attention should be paid to the presence of cysts in the liver and pancreas, with special attention given to liver cysts and cystic dilatation of the bile ducts. Liver fibrosis, signs of portal hypertension (splenomegaly, collateral circulation, direction and velocity of flow on portal vein Doppler [duplex scanning of the inferior vena cava and portal system veins]), pancreatic hypoplasia, or aplasia of the pancreatic tail are also extrarenal manifestations of kidney diseases accompanied by cyst formation [23,36,37,38].

It is recommended to perform a pelvic ultrasound (bladder ultrasound, transabdominal uterus and adnexa ultrasound / prostate ultrasound) in children with a detected simple renal cyst to identify extrarenal signs characteristic of other cystic renal diseases (for differential diagnosis) [23,35].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comment: examination of the pelvic organs (bladder ultrasound, transabdominal uterus and adnexa ultrasound / prostate ultrasound) is also a standard part of the evaluation when simple renal cysts are detected. Findings such as hematocolpos, seminal vesicle cysts, and other pelvic anomalies are indications for an extended patient evaluation to establish a definitive diagnosis [39,40,41,42,43].

Not recommended for children with a diagnosed renal cyst in the absence of features atypical for a simple cyst is routine contrast-enhanced magnetic resonance imaging (MRI) of the kidneys—it is performed according to indications and, when available, for differential diagnostic purposes. Anesthesia management (including early postoperative care) is indicated for conditions that prevent the patient from remaining still for the required period of time [1,18,44,45,78].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comments: contrast-enhanced magnetic resonance imaging of the kidneys is indicated for [1,44]:

- large cysts in young children;

- presence of any pronounced symptoms (e.g., hematuria);

- suspicion of a malignant tumor;

- tuberous sclerosis;

- assessment of kidney size primarily in autosomal dominant polycystic kidney disease, as it allows a more accurate assessment of kidney size compared to ultrasound diagnostics;

- differential diagnosis of a simple renal cyst from a caliceal diverticulum [45];

- insufficient informativeness or unavailability of computed tomography of the kidneys and upper urinary tract with intravenous bolus contrast enhancement.

In the case of a simple cyst, follow-up ultrasound examinations (renal ultrasound and urinary tract ultrasound) at specified intervals are generally sufficient [1].

Indications for other instrumental examinations are determined by the list of diseases with which differential diagnosis is performed.

2.5 Other Procedures

  • In patients with a solitary simple cyst and unconfirmed renal disease, genetic testing is not recommended due to a lack of utility [1].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comment: the detection of a solitary cyst in an intact kidney during prenatal screening, provided there are no extrarenal anomalies, is not an indication for prenatal genetic testing, neither in the prenatal nor in the postnatal period, as the probability of detecting gene mutations is quite low, especially with a negative family history of ADPKD [23,46].

  • Molecular genetic testing (e.g., detection of a mutation in the PKD1) gene is recommended for patients with a simple renal cyst and symptoms, or in case of an increasing number of cysts over time, even in the absence of a family history of cystic kidney diseases (the necessity and scope of testing are determined by a geneticist (initial/follow-up geneticist consultation) [46].

Level of Recommendations CLevel of Evidence 5Level of Recommendations C (Level of Evidence – 5)

Other examinations and specialist consultations are performed as indicated during the differential diagnosis and identification of comorbid pathology in patients with a simple renal cyst.

2.5.1 Differential Diagnosis

It is recommended, since a simple renal cyst may be the onset of diseases accompanied by progressive cystic involvement of the renal parenchyma, that all patients undergo differential diagnosis with the following nosological forms:

1. Polycystic kidney diseases / ciliopathies:

- ADPKD,

- ARPKD,

- other ciliopathies (including juvenile nephronophthisis, Joubert syndrome (rare).

2. Tuberous sclerosis.

3. Cystic dysplasia:

- cystic dysplasia associated with congenital anomalies of the kidney and urinary tract,

- HNF1B-associated kidney diseases,

- cystic dysplasia / multicystic dysplastic kidney associated with syndromic disorders.

4. Caliceal diverticulum (see section 2.4).

5. Acquired cysts (post-traumatic cysts, cysts resulting from infectious inflammation, malignant processes) [24].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comments: nosologies for differential diagnosis are selected in accordance with clinical symptoms. The scheme for the differential diagnosis of simple renal cysts with ADPKD is presented in Appendix B.

3. Treatment, including drug and non-drug therapies, diet therapy, and pain management

Most asymptomatic renal cysts require only dynamic monitoring of both cyst characteristics and trends in clinical symptom changes, the course of arterial hypertension, and renal excretory function [70,71].

Indications for surgical treatment are changes in the cyst, worsening clinical manifestations, and suspicion of a tumor process.

3.1 Conservative Treatment

Conservative treatment of a solitary cyst as a nosological entity is not performed. Patients are monitored dynamically to clarify the diagnosis (e.g., in cases where a solitary cyst is the first sign of polycystic kidney disease) and to prevent complications, including the development of chronic kidney disease (see sections 2.5 "Instrumental Diagnostic Examinations" and 5.2 "Dispensary Follow-up").

In CKD, treatment is carried out in accordance with current clinical guidelines.

3.2 Surgical Treatment

Renal cysts tend to increase in number and size with age, while spontaneous regression is extremely rare. In the case of an established diagnosis of a simple solitary renal cyst in a child, treatment is mostly not required, and a long-term follow-up strategy is chosen since complications are relatively rare [47].

To date, there are no absolute indications for surgical intervention for simple solitary cysts in children [48].

However, the presence of symptoms such as rapid cyst enlargement, hematuria, the onset of arterial hypertension, pain syndrome, and superimposed infections constitute indications for surgical intervention [12,47,49].

Approaches to surgical techniques also vary from minimally invasive interventions (percutaneous puncture with sclerotherapy) to endovideosurgical cyst fenestration (laparoscopic, retroperitoneoscopic, robotic) to open surgery. The use of minimally invasive surgical treatments is a priority for pediatric surgery and pediatric urology-andrology [32,50,74].

Surgical treatment is recommended in children with large renal cysts with intraparenchymal, parapelvic, cortical, and subcortical locations [32,50,74,75].

LeRR CLoE 4Level of recommendation confidence C (level of evidence – 4)

Comment: "Large cyst size" is a relative concept and requires individual consideration for each patient, and directly depends on factors such as patient age, kidney size, and the ratio of cyst size to kidney size (or cyst area relative to renal parenchyma area). Surgical treatment is used for cysts larger than 3 cm, rapid growth of the renal cyst, or when its size exceeds 30% of the kidney size [31,32,74].

It is recommended to perform puncture drainage and sclerosis (including staged sclerosis) of a renal cyst (percutaneous cyst puncture with aspiration of contents and simultaneous administration of a sclerosing agent) (performed under ultrasound guidance), for example, #ethanol** (concentrate for solution for topical use) in a volume of 25–75% of the obtained volume with an exposure time of 5–15 minutes [31,32]. The duration and frequency of administration are determined individually: until the cystic cavity decreases and the drainage is removed: cavity size – up to 1.5 cm (determined by the diameter of the drainage system curl), second criterion – absence of drainage discharge (is the factor determining the possibility of removing the system). Indications for surgery are large renal cysts with cortical and subcortical locations [29,32,51,69].

LeRR CLoE 4Level of recommendation confidence C (level of evidence – 4)

Comments:

o "Large cyst" is a relative concept and requires individual consideration for each patient, and directly depends on factors such as patient age, kidney size, and the ratio of cyst size to kidney size (or cyst area relative to renal parenchyma area).

o Surgical treatment is used for cysts larger than 3 cm [31,32].

Surgical technique: the operation is performed with the patient in the prone position with a bolster placed under the chest or in the lateral position. During renal ultrasound, the dimensions and location of the cyst are assessed. Then, using a navigator, the trajectory of the puncture needle is calculated. Special puncture sets for draining cavity formations (stylet-catheter) with a pigtail catheter (8–10 Ch nephrostomy puncture sets) are used for the puncture (e.g., nephrostomy set, medical sets for minimally invasive interventions to the diagnostic and treatment complex, percutaneous urological nephrostomy sets, percutaneous nephrostomy set, etc.). After entering the cyst cavity, the contents are aspirated and administered.

A positive treatment outcome is regression of the cyst or a reduction in its size by more than 50%.

During puncture, the needle may pass in close proximity to the major vessels and the pelvicalyceal system of the kidney; therefore, it is very crucial to select the needle trajectory so as to avoid injuring the aforementioned structures.

It is not recommended to perform routine simple puncture aspiration of cyst contents in children with a renal cyst due to the significantly lower efficacy of simple aspiration. In most cases, aspiration should be accompanied by the injection of a sclerosing agent to destroy the epithelial lining of the renal cyst (including its phased administration). In rare cases (when cysts have a parapelvic location), simple puncture aspiration of the cyst contents is acceptable [52,69].

GDR CLE 5Grade of recommendation C (level of evidence – 5)

It is recommended to perform video-endosurgical (laparoscopic, retroperitoneoscopic, robotic) decortication (fenestration) of the cyst (laparoscopic excision of renal cyst) in children with a large renal cyst with cortical, subcortical, or parapelvic location [47,53,74].

GRC CLEL 4Grade of Recommendation C (Level of Evidence – 4)

Comments:

o A "large cyst" is a relative concept that requires individual consideration for each patient and directly depends on such factors as the patient's age, kidney size, and the ratio of cyst size to kidney size (or cyst area relative to renal parenchyma area).

o Surgical treatment is used for cysts larger than 3 cm [31,32].

o The puncture method (puncture drainage, sclerotherapy of the renal cyst) is not indicated for parapelvic cysts due to the risks of damaging the vascular and pelvicalyceal structures of the kidney. Therefore, surgical intervention must be performed under visual endoscopic (laparoscopic) control.

It is recommended to perform video-endosurgical (laparoscopic, retroperitoneoscopic, robotic) decortication (fenestration) of the cyst (laparoscopic excision of renal cyst) in children with a renal cyst in case of unsuccessful attempts at puncture sclerotherapy of cysts [33,47,74].

LeRR CLoE 4Level of recommendation confidence C (level of evidence – 4)

Comments: one of the indications for laparoscopic cyst decortication is prior unsuccessful attempts at cyst sclerotherapy or cyst recurrence after sclerotherapy [33,47].

It is recommended to perform video-endosurgical (laparoscopic, retroperitoneoscopic, robotic) decortication (fenestration) of the cyst (laparoscopic excision of renal cyst) in children with a renal cyst in case of rapid cyst growth [33,47,74].

GRC CLEL 4Grade of Recommendation C (Level of Evidence – 4)

It is recommended to perform video-endosurgical (laparoscopic, retroperitoneoscopic, robotic) decortication (fenestration) of the cyst (laparoscopic excision of renal cyst) in children with symptomatic renal cysts (presence of pain syndrome in the lumbar and/or abdominal region, gross hematuria, compression of the upper urinary tract by the cyst, arterial hypertension) [47,53].

LeRR CLoE 4Level of recommendation confidence C (level of evidence – 4)

3.3 Other Treatment

Not applicable.

4. Medical Rehabilitation and Sanatorium-Resort Treatment

Not performed.

5. Prevention and Dispensary Observation

5.1 Prevention

Specific prevention does not exist.

It is recommended to perform dynamic follow-up in children with renal cysts below grade II and further evaluation in the presence of a grade III or IV renal cyst in order to assess the condition dynamically, including clarifying the diagnosis and making timely decisions on changing the treatment tactics [72,73].

LeRR CLoE 4Level of recommendation confidence C (level of evidence – 4)

Comment: for details, see section 2 and subsection 5.3.

5.2 Vaccination

A solitary renal cyst is not a contraindication to vaccination using any type of vaccines, nor to vaccination against the novel coronavirus infection (COVID-19), in accordance with the drug prescribing information.

5.3 Dispensary follow-up

When a simple solitary cyst is detected in a child, dynamic/dispensary follow-up without active medical intervention is indicated, since, as mentioned above, complications develop rarely, and the risk of malignant transformation of such cysts is practically reduced to zero [1,34,54,55].

At the same time, unlike in adults, the growth of a simple renal cyst in children can be very rapid, leading to complications such as compression of the kidney, renal vessels, cyst rupture, etc. [48].

It should be remembered that the key factor in developing the follow-up algorithm for a child with a simple renal cyst is that the onset of autosomal dominant polycystic kidney disease (ADPKD) has a similar ultrasound presentation, and a series of regular ultrasound and laboratory studies is required to definitively rule it out. In addition, 10-15% of patients with ADPKD have a negative family history.

It is recommended to conduct dynamic/dispensary follow-up of a patient with a diagnosed simple renal cyst (dispensary appointment (examination, consultation) by a pediatric urologist-andrologist / dispensary appointment (examination, consultation) by a urologist / dispensary appointment (examination, consultation) by a pediatric surgeon and dispensary appointment (examination, consultation) by a pediatrician (or initial and follow-up pediatrician appointments (examinations, consultations)) / dispensary appointment (examination, consultation) by a general practitioner (family physician) (or initial and follow-up general practitioner (family physician) appointments (examinations, consultations)) and/or dispensary appointment (examination, consultation) by a nephrologist (or initial and follow-up nephrologist appointments (examinations, consultations))), including measurement of blood pressure in peripheral arteries for the timely diagnosis of arterial hypertension [1].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comments: on average annually, or more frequently if necessary.

It is recommended during dynamic/dispensary follow-up of a patient with a diagnosed simple renal cyst to perform annual renal ultrasound and urinary tract ultrasound in order to assess cyst growth, their number, changes in their characteristics (including determination of cyst content density and wall thickness), and timely diagnosis of ADPKD onset [1,74,76].

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

Comments: annual evaluation should be continued for 5 years and/or until the age of 15 years. If no changes are present, a definitive diagnosis of a simple renal cyst can be established. Thereafter, annual ultrasound of the kidneys and urinary tract can be discontinued and performed only when indicated [1].

Intensive growth of a renal cyst is defined as an increase in cyst size of more than 5% from the baseline value over a 24-month follow-up period, which is an indication for surgical treatment. An effective method for calculating the renal cyst growth coefficient is its estimation based on length, and it is advisable to use the formula: CGCL = [LK2/LR2 - LK1/LR1] * 100%, where CGCL is the cyst growth coefficient by length; LK is the cyst length in mm; LR is the kidney length in mm; 1 – baseline values; 2 – values at 12 and 24 months after obtaining the baseline [74,75].

It is recommended for patients who show no negative dynamics in the ultrasound appearance of cysts or no arterial hypertension during dynamic follow-up to undergo laboratory testing on average once a year, or more frequently if indicated—for example, in a patient with a simple renal cyst to rule out/confirm other renal lesions, including the onset of ADPKD, the following tests are performed:

- Complete (clinical) urinalysis,

- Complete (clinical) blood count with differential,

- Blood creatinine level test,

- Acid-base balance and blood gas analysis [1,24,25].

CGR CLOE 5Level of Evidence / Grade of Recommendation: C-5

The diagnostic flowchart is presented in Appendix B.

6. Organization of Medical Care

Children with a renal cyst may, depending on necessity, receive any type, conditions, and form of medical care provided for by the legislation of the Russian Federation.

Patients with a renal cyst must be registered under dispensary follow-up, receiving primary health care in outpatient settings. The main condition for providing care to a patient with urolithiasis must be ensuring continuous monitoring and timely hospitalization.

The child is monitored by a pediatrician / general practitioner (family physician), pediatric urologist-andrologist / urologist / pediatric surgeon, nephrologist, with the participation, if necessary, of a geneticist and physicians of other specialties (e.g., otorhinolaryngologist, pediatric otorhinolaryngologist / audiologist, pediatric dentist / dentist, ophthalmologist, obstetrician-gynecologist, etc.).

Indications for planned hospitalization:

1) Need for surgical intervention;

3) Need for diagnostics requiring the child to stay in a hospital.

Indications for emergency hospitalization:

1) Uncontrolled pain syndrome caused by urinary tract stones;

3) Life-threatening complications.

The organization of dietary nutrition for patients during inpatient treatment in medical organizations is carried out in accordance with Appendix 3 of the Order of the Russian Ministry of Health No. 1008n dated September 23, 2020, "On Approval of the Procedure for Providing Patients with Therapeutic Nutrition".

7. Additional Information

Follow-up studies on the natural history of prenatally detected "simple" cysts indicate that some of these lesions, especially when the cyst diameter exceeds 20 mm in the prenatal period, require special medical attention. A solitary cyst in a normal kidney may be the first manifestation of polycystic kidney disease or, in rare cases, an oncological pathology. On the other hand, it may be a "simple" self-resolving lesion or an asymptomatic incidental finding that does not require medical intervention [17, 18].

Evidence suggests that in adult patients, microstructural changes, including the formation of diverticula and microcysts, are already observed in the kidney before a simple renal cyst is detected. It has been shown that all kidneys in adults and elderly individuals have diverticula on the distal tubule, and their number increases with age [56, 57].

Risk factors for the formation of renal cysts over a lifetime with aging include arterial hypertension [57, 58], diabetes [59], arteriosclerosis [60], and hyperuricemia [61]. Adult patients with a simple renal cyst, compared to adults without renal cysts, more frequently exhibit higher levels of peripheral blood pressure, fasting plasma glucose, blood lipids, uric acid, and serum creatinine, along with a lower glomerular filtration rate.

Criteria for Evaluating the Quality of Medical Care

№

Quality criteria

Performance assessment (yes/no)

1.

Renal ultrasound, urinary tract ultrasound with/or urinary tract ultrasound with color Doppler mapping (duplex scanning of renal arteries) performed during diagnosis

Yes/No

2.

Annual renal ultrasound and urinary tract ultrasound performed during follow-up/dispensary observation

Yes/No

3.

General (clinical) urinalysis performed during diagnosis

Yes/No

4.

Blood creatinine and blood urea levels assessed during diagnosis

Yes/No

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  64. M.G. Harisinghani, M.M. Maher, D.A. Gervais, F. McGovern, P. Hahn, K. Jhaveri, et al. Incidence of malignancy in complex cystic renal masses (Bosniak category III): should imaging-guided biopsy precede surgery? AJR Am J Roentgenol, 180 (2003), pp. 755-758.

  65. M.C. Wallis, A.J. Lorenzo, W.A. Farhat, D.J. Bagli, A.E. Khoury, J.L. Pippi Salle Risk assessment of incidentally detected complex renal cysts in children: potential role for a modification of the Bosniak classification J Urol, 180 (2008), pp. 317-321.

  66. M. Kubo, K. Iwashita, N. Oyachi, T. Oyama, T. Yamamoto Two different types of infantile renal cell carcinomas associated with tuberous sclerosis J Pediatr Surg, 46 (2011), pp. E37-E41.

  67. Y. Peng, L. Jia, N. Sun, J. Li, L. Fu, J. Zeng, et al. Assessment of cystic renal masses in children: comparison of multislice computed tomography and ultrasound imaging using the Bosniak classification system Eur J Radiol, 75 (2010), pp. 287-292.

  68. Renal function in children with a congenital solitary functioning kidney: A systematic review Kelly Ann Hutchinson, Lyra Halili, Andre Guerra, Pavel Geier, Melise Keays, Luis Guerra. Journal of Pediatric Urology (2021) 17, 556e565.

  69. Vrublevskaya E.N. Diagnostics and tactics of surgical treatment of cortical cystic renal lesions in children. Dr. Med. Sci. Diss. Summary. Moscow; 2010. 40 p. (In Russ.)

  70. K McHugh, DA Stringer, D Hebert, et al. Simple renal cysts in children: diagnosis and follow-up with US Radiology, 178 (1991), p. 383.

  71. F O'Kelly, K McAlpine, N Abdeen, et al. The prevalence, clinicodemographics, and outcomes of incidental and symptomatic renal cysts in a pediatric cohort undergoing ultrasonography J Urol, 202 (2019), p. 394].

  72. GM Israel, MA Bosniak An update of the Bosniak renal cyst classification system Urology, 66 (2005), p. 484. T Chandrasekar, AE Ahmad, K Fadaak, et al. Natural history of complex renal cysts: clinical evidence supporting active surveillance J Urol, 199 (2018), p. 633.

  73. IG Schoots, K Zaccai, MG Hunink, et al. Bosniak classification for complex renal cysts reevaluated: asystematic review J Urol, 198 (2017), p. 12.

  74. Akramov N.R., Baybikov R.S. Examination and determination of indications for surgical treatment of children with cystic kidney diseases. Detskaya Khirurgiya. 2016;20(1):45-49. DOI: 10.18821/1560-9510-2016-20-1-45-49. EDN: VLEIDR. (In Russ.)

  75. Akramov N.R., Baybikov R.S., Zakirov A.K., Gallyamova A.I. Method for dynamic monitoring of solitary renal cysts in children. Russian Federation Patent no. 2620356 C; 2017. EDN: VGKCFI. (In Russ.)

  76. Rediger C, Guerra LA, Keays MA, Wayne C, Reddy D, Ksara S, Leonard MP. Renal cyst evolution in childhood: a contemporary observational study. J Pediatr Urol. 2019 Apr;15(2):188.e1-188.e6. doi: 10.1016/j.jpurol.2019.01.006. Epub 2019 Feb 1. PMID: 30808538.

  77. Ong ACM, Carriazo S, Ma BM, Torra R, Pei Y. Autosomal dominant polycystic kidney disease. Lancet. 2026 Mar 28;407(10535):1289-1302. doi: 10.1016/S0140-6736(26)00046-2. Epub 2026 Feb 27. PMID: 41771281.

  78. Artunduaga M, Liu CA, Morin CE, Serai SD, Udayasankar U, Greer MC, Gee MS. Safety challenges related to the use of sedation and general anesthesia in pediatric patients undergoing magnetic resonance imaging examinations. Pediatr Radiol. 2021 May;51(5):724-735. doi: 10.1007/s00247-021-05044-5. Epub 2021 Apr 16. PMID: 33860861; PMCID: PMC8049862.

Appendix A1. Working Group Composition

  1. Akramov N.R., Dr. Med. Sci., Professor, Head of the Department of Urology, Nephrology, and Transplantology, Kazan State Medical Academy – a branch of the Russian Medical Academy of Continuous Professional Education of the Russian Ministry of Health, Head of the Pediatric Department, Dion Medical Group LLC.

  2. Baranov A.A., Academician of the RAS, Professor, Dr. Med. Sci.; Honorary President of the Union of Pediatricians of Russia, Advisor to the Head of the Research Institute of Pediatrics and Child Health, National Medical Research Center No. 2 of the Petrovsky National Research Centre of Surgery, Professor at the Department of Pediatrics and Pediatric Rheumatology, I.M. Sechenov First Moscow State Medical University of the Ministry of Health of Russia (Sechenov University), Chief freelance pediatric specialist of the Russian Ministry of Health.

  3. Belyaeva I.A., Dr. Med. Sci., Head of the Department of Preconceptional, Antenatal, and Neonatal Medicine, Research Institute of Pediatrics and Child Health, National Medical Research Center No. 2 of the Petrovsky National Research Centre of Surgery, Professor at the Department of Faculty Pediatrics, Pediatric Faculty, Pirogov Russian National Research Medical University of the Ministry of Health of Russia, Member of the Union of Pediatricians of Russia, Honorary Professor of the Russian Association of Perinatal Medicine Specialists.

  4. Burkin A.G., Pediatric Urologist-Andrologist, Cand. Med. Sci., Head of the Department of Pediatric Urology-Andrology, Z.A. Bashlyeva Children's City Clinical Hospital of the Moscow Healthcare Department.

  5. Vrublevskaya E.N., Dr. Med. Sci., Head of the Surgical Department, V.F. Voyno-Yasenetsky Scientific and Practical Center for Specialized Medical Care for Children of the Moscow Healthcare Department, Associate Professor at the Academician Yu.F. Isakov Department of Pediatric Surgery, Pirogov Russian National Research Medical University of the Ministry of Health of Russia.

  6. Vrublevsky S.G., Dr. Med. Sci., Professor, Professor at the Academician Yu.F. Isakov Department of Pediatric Surgery, Pirogov Russian National Research Medical University (Pirogov University), Chief freelance pediatric urologist-andrologist of the Moscow Healthcare Department, Deputy Chief Medical Officer for Surgery, V.F. Voyno-Yasenetsky Scientific and Practical Center for Specialized Medical Care for Children of the Moscow Healthcare Department.

  7. Guseynov A.Ya., Cand. Med. Sci., Head of the Pediatric Uroandrological Department, Russian Children's Clinical Hospital — a branch of Pirogov Russian National Research Medical University of the Ministry of Health of Russia, Pediatric Urologist-Andrologist.

  8. Zhamynchiev E.K., Cand. Med. Sci., Pediatric Urologist-Andrologist, Research Institute of Pediatrics and Child Health, National Medical Research Center No. 2 of the Petrovsky National Research Centre of Surgery, Member of the Union of Pediatricians of Russia.

  9. Zhurkova N.V., Cand. Med. Sci., Leading Researcher, Research Institute of Pediatrics and Child Health, National Medical Research Center No. 2 of the Petrovsky National Research Centre of Surgery, Member of the Union of Pediatricians of Russia, Member of the Association of Medical Geneticists.

  10. Zokirov N.Z., Dr. Med. Sci., Head of the Department, Academy of Postgraduate Education, Federal Research and Clinical Center of the Federal Medical-Biological Agency, Federal Research and Clinical Center of Children and Adolescents of the Federal Medical-Biological Agency, Member of the Union of Pediatricians of Russia.

  11. Ivardava M.I., Cand. Med. Sci., Head of the General Pediatrics Department, Pediatrician, Head of the Department for the Development of Scientific Approaches to the Management of Children with Motor Disorders, Research Institute of Pediatrics and Child Health, National Medical Research Center No. 2 of the Petrovsky National Research Centre of Surgery, Member of the Union of Pediatricians of Russia.

  12. Kozyrev G.V., Dr. Med. Sci., Head of the Department of Pediatric Urology-Andrology, Patrice Lumumba Peoples' Friendship University of Russia (RUDN University), Professor at the L.P. Alexandrov Department of Pediatric Surgery and Urology-Andrology, Sechenov University, Head of the Committee on Pediatric Urology of the Russian Society of Urology, Director of the Association of Pediatric Urology-Andrologist Specialists (APUAS).

  13. Korochkin M.V., Head of the Short-Term Stay Hospital Department (Surgery Profile), Pediatric Surgeon of the highest qualification category, Urologist-Andrologist, holder of the "Moscow Doctor" status, Morozov Children's City Clinical Hospital of the Moscow Healthcare Department.

  14. Margieva T.V., Cand. Med. Sci., Chief Specialist of the Methodological Center for Specialist Accreditation, I.M. Sechenov First Moscow State Medical University of the Ministry of Health of Russia (Sechenov University), Nephrologist, Member of the Union of Pediatricians of Russia.

  15. Namazova-Baranova L.S., Academician of the RAS, Professor, D.Sc. (Medicine), President of the Union of Pediatricians of Russia; Past President of EPA/UNEPSA; Head of the Research Institute of Pediatrics and Child Health of the National Medical Research Center No. 2 of the Petrovsky National Research Centre of Surgery, Head of the Department of Faculty Pediatrics, Faculty of Pediatrics, Pirogov Russian National Research Medical University of the Russian Ministry of Health, Chief freelance pediatric specialist in preventive medicine of the Russian Ministry of Health.

  16. Platonova M.M., Ph.D. (Medicine), Researcher at the Research Institute of Pediatrics and Child Health, National Medical Research Center No. 2 of the Petrovsky National Research Centre of Surgery, pulmonologist.

  17. Privalova T.E., Ph.D. (Medicine), Associate Professor, Head of Academic Affairs at the Department of Faculty Pediatrics, Faculty of Pediatrics, Pirogov Russian National Research Medical University of the Russian Ministry of Health, Leading Researcher at the Department of Social Pediatrics and Organization of Multidisciplinary Care for Children, Head of Department / Pediatrician at the Research Institute of Pediatrics and Child Health, National Medical Research Center No. 2 of the Petrovsky National Research Centre of Surgery, member of the Union of Pediatricians of Russia.

  18. Selimzyanova L.R., Ph.D. (Medicine), Head of the Department of Standardization and Study of Evidence-Based Medicine Foundations at the Research Institute of Pediatrics and Child Health, National Medical Research Center No. 2 of the Petrovsky National Research Centre of Surgery, Associate Professor at the Department of Pediatrics and Pediatric Rheumatology, I.M. Sechenov First Moscow State Medical University of the Russian Ministry of Health (Sechenov University), Associate Professor at the Department of Faculty Pediatrics, Faculty of Pediatrics, Pirogov Russian National Research Medical University of the Russian Ministry of Health, member of the Union of Pediatricians of Russia.

  19. Smirnova O.Ya., geneticist, Senior Researcher at the Department of Standardization and Study of Evidence-Based Medicine Foundations, Research Institute of Pediatrics and Child Health, National Medical Research Center No. 2 of the Petrovsky National Research Centre of Surgery, member of the Union of Pediatricians of Russia.

  20. Tepaev R.F., D.Sc. (Medicine), Head of the Anesthesiology and Intensive Care Service, Bashlyeva Children's City Clinical Hospital, Professor at the Department of Pediatrics and Pediatric Rheumatology, I.M. Sechenov First Moscow State Medical University of the Russian Ministry of Health (Sechenov University).

  21. Turov F.O., Ph.D. (Medicine), Leading Researcher, pediatric urologist-andrologist at the Scientific and Practical Center for Specialized Medical Care for Children of the Moscow City Health Department, member of the Russian Society of Urology, member of the American Urological Association, member of the Union of Pediatricians of Russia.

  22. Turti T.V., D.Sc. (Medicine), Chief Researcher at the Department of Preconceptional, Antenatal, and Neonatal Medicine, Research Institute of Pediatrics and Child Health, National Medical Research Center No. 2 of the Petrovsky National Research Centre of Surgery, Professor at the Department of Faculty Pediatrics, Faculty of Pediatrics, Pirogov Russian National Research Medical University of the Russian Ministry of Health, member of the Union of Pediatricians of Russia.

  23. Fedoseenko M.V., Ph.D. (Medicine), Head of the Department for the Development of Scientific Approaches to Immunization of Patients with Health Deviations and Chronic Diseases, Leading Researcher, pediatrician at the Research Institute of Pediatrics and Child Health, National Medical Research Center No. 2 of the Petrovsky National Research Centre of Surgery, Associate Professor at the Department of Faculty Pediatrics, Faculty of Pediatrics, Pirogov Russian National Research Medical University of the Russian Ministry of Health, member of the Union of Pediatricians of Russia.

  24. Shmyrov O.S., Ph.D. (Medicine), Head of the Department of Pediatric Urology and Andrology, pediatric surgeon, pediatric urologist-andrologist, Morozov Children's City Clinical Hospital of the Moscow City Health Department.

  25. Yatsyk S.P., D.Sc. (Medicine), Corresponding Member of the RAS, Professor at the Department of Pediatric Surgery, Russian Medical Academy of Continuous Professional Education of the Russian Ministry of Health.

Appendix A2. Methodology for Developing Clinical Guidelines

Target audience for these clinical guidelines:

  1. Pediatricians

  2. General practitioners (family physicians)

  3. Pediatric urologists-andrologists

  4. Pediatric surgeons

  5. Nephrologists

  6. Ultrasound diagnostics physicians

  7. Radiologists

Table 1. Scale for assessing the levels of evidence (LE) for diagnostic methods (diagnostic interventions)

LoE

Definition

1

Systematic reviews of studies with reference standard control or systematic reviews of randomized controlled trials with meta-analysis

2

Individual studies with reference standard control or individual randomized controlled trials and systematic reviews of studies of any design, except randomized controlled trials, with meta-analysis

3

Studies without consecutive reference standard control or studies with a reference standard not independent of the test method, or non-randomized comparative studies, including cohort studies

4

Non-comparative studies, case report

5

Only justification of mechanism of action or expert opinion is available

Table 2. Scale for assessing the levels of evidence (LE) for prevention, treatment, and medical rehabilitation methods, including those based on natural therapeutic factors (preventive, therapeutic, and rehabilitation interventions)

LoE

Definition

1

Systematic review of RCTs with meta-analysis

2

Individual RCTs and systematic reviews of studies of any design except RCTs, with meta-analysis

3

Non-randomized comparative studies, including cohort studies

4

Non-comparative studies, case reports or case series, case-control studies

5

Only justification of the mechanism of action of the intervention (preclinical studies) or expert opinion is available

Table 3. Scale for assessing the grades of recommendation (GR) for prevention, diagnostic, treatment, and medical rehabilitation methods, including those based on natural therapeutic factors (preventive, diagnostic, therapeutic, and rehabilitation interventions)

GoR

Definition

A

Strong recommendation (all considered efficacy criteria (outcomes) are important, all studies are of high or acceptable methodological quality, and their conclusions on the outcomes of interest are consistent)

B

Conditional recommendation (not all considered efficacy criteria (outcomes) are important, not all studies are of high or acceptable methodological quality, and/or their conclusions on the outcomes of interest are inconsistent)

C

Weak recommendation (lack of adequate quality evidence (all considered efficacy criteria (outcomes) are unimportant, all studies are of low methodological quality, and their conclusions on the outcomes of interest are inconsistent)

Procedure for updating clinical guidelines.

The mechanism for updating clinical guidelines provides for their systematic revision at least once every three years, as well as upon the emergence of new evidence-based medicine data on the diagnosis, treatment, prevention, and rehabilitation of specific diseases, or in the presence of justified additions/comments to previously approved clinical guidelines, but no more frequently than once every 6 months.

Appendix A3. Reference Materials

Care delivery pathways:

  1. Order of the Ministry of Health of the Russian Federation No. 120n dated February 20, 2026, "On Approval of the Procedure for Providing Medical Care in the Profile 'Pediatrics'."

  2. Order of the Ministry of Health of the Russian Federation No. 562n dated October 31, 2012, "On Approval of the Procedure for Providing Medical Care in the Profile 'Pediatric Surgery'."

Other documents:

  1. Order of the Ministry of Health of the Russian Federation No. 1094n dated November 24, 2021, "On Approval of the Procedure for Prescribing Medicinal Products, Prescription Forms for Medicinal Products, the Procedure for Issuing Said Forms, Their Accounting and Storage, Prescription Form Forms Containing Designations for Narcotic Drugs or Psychotropic Substances, the Procedure for Their Manufacture, Distribution, Registration, Accounting and Storage, as well as the Rules for Issuing Prescription Forms, Including in the Form of Electronic Documents."

  2. International Statistical Classification of Diseases and Related Health Problems (ICD-10).

  3. Order of the Ministry of Health of the Russian Federation No. 205n dated May 2, 2023, "On Approval of the Nomenclature of Positions of Medical and Pharmaceutical Workers."

  4. Order of the Ministry of Health of the Russian Federation No. 541n dated May 2, 2023, "On Approval of the Unified Qualification Reference Book of Positions of Managers, Specialists, and Employees," section "Qualification Characteristics of Positions of Healthcare Industry Workers."

  5. Federal Law No. 489-FZ dated December 25, 2018, "On Amendments to Article 40 of the Federal Law 'On Compulsory Medical Insurance in the Russian Federation' and the Federal Law 'The Fundamentals of Healthcare Protection of Citizens in the Russian Federation' Regarding Clinical Practice Guidelines."

  6. Order of the Ministry of Health of the Russian Federation No. 103n dated February 28, 2019, "On Approval of the Procedure and Deadlines for the Development of Clinical Practice Guidelines, Their Revision, the Standard Form of Clinical Practice Guidelines, and Requirements for Their Structure, Composition, and Scientific Validity of Information Included in Clinical Practice Guidelines."

  7. Order of the Ministry of Health of the Russian Federation No. 804n dated October 13, 2017, "On Approval of the Nomenclature of Medical Services."

  8. Order of the Ministry of Health of the Russian Federation No. 1122n dated December 6, 2021, "On Approval of the National Immunization Schedule, the Schedule of Immunization by Epidemiological Indications, and the Procedure for Conducting Immunizations."

  9. Methodological Guidelines "MU 3.3.1.1095-02. 3.3.1. Vaccine Prophylaxis. Medical Contraindications to Preventive Vaccinations with Preparations of the National Immunization Schedule. Methodological Guidelines."

  10. Order of the Ministry of Health of the Russian Federation No. 1008n dated September 23, 2020, "On Approval of the Procedure for Providing Patients with Therapeutic Nutrition."

Appendix B. Physician Action Algorithms

Algorithm of physician actions for a simple solitary renal cyst in children [1]

Appendix B. Physician Action Algorithms — Renal cyst in children

Note:

CAKUT — congenital anomalies of the kidney and urinary tract

Appendix C. Patient Information

Simple (solitary) renal cysts are usually an incidental finding and can be diagnosed by ultrasound examination both in the prenatal period and at any time of life.

In most cases, simple renal cysts are asymptomatic, but in some cases the following may be observed:

- pain (in large cysts) due to compression of adjacent organs;

- changes in urine color (blood in urine);

- infection and/or suppuration of the cyst with clinical manifestations of an acute inflammatory process;

- arterial hypertension, although the causal relationship has not yet been fully studied;

- urinary tract infections.

Simple cysts can be diagnosed prenatally and resolve spontaneously before birth.

Solitary simple cysts require a consultation with a pediatric urologist-andrologist/pediatric surgeon and further follow-up according to their recommendations. Surgery may be required in some cases.

Some patients, especially if the cyst diameter is greater than 20 mm in the prenatal period, require special medical attention. Sometimes a solitary cyst in a normal kidney can be the first manifestation of polycystic kidney disease or, in rare cases, oncological pathology. On the other hand, it can be a "simple" self-resolving formation or an asymptomatic finding that does not require medical intervention.

A child with a newly diagnosed unilateral renal cyst needs to be evaluated for any complaints, as well as for the presence of renal cysts or cysts in other organs among close relatives. A geneticist consultation may sometimes be required.

Appendix G. Assessment Scales, Questionnaires, and Other Evaluation Tools

Not applicable.

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