Radiological syndromes

Syndromes in infectious pulmonary lesions

Radiodiagnosis plays a key role in identifying specific patterns in respiratory infections. The evaluation of the imaging presentation depends on the type of pathogen and the patient's immune status.

• Viral pneumonias: Encompass a wide spectrum of manifestations, from pandemic H1N1 influenza to MERS-CoV. Outpatient recipients of allogeneic hematopoietic stem cell transplantation require special attention, as the course of influenza in them has specific features.
• Specific syndromes and complications: The formation of a bronchopleural fistula (bronchopleural fistula) is a formidable complication requiring advanced imaging techniques. Parasitic infestations, such as schistosomiasis (schistosomiasis), lead to the development of pulmonary arterial hypertension. Radiologically, this manifests as marked dilatation of the pulmonary artery and the formation of giant aneurysms.
• Immune reconstitution inflammatory syndrome (IRIS): Occurs in immunocompromised individuals (e.g., in HIV infection at the start of antiretroviral therapy). A clear understanding of the pathomorphological aspects of this syndrome is necessary for correct interpretation of the imaging findings.

Osteoarticular syndrome in haemochromatosis

Haemochromatosis (haemochromatosis) is traditionally described by a triad: skin pigmentation, liver cirrhosis, and "bronze diabetes". Laboratory confirmation of the disease is provided by high serum ferritin levels. However, joint involvement and chondrocalcinosis often present as the initial manifesting symptoms.

The radiological presentation of arthropathy externally resembles osteoarthritis, but has a strictly specific distribution pattern:

1. Localization: Predominantly affects the 2nd and 3rd metacarpophalangeal joints (index and middle fingers).
2. Sparing: Interphalangeal joints remain relatively intact.
3. Key symptom: The appearance of hook-like osteophytes (hook-like osteophytes) on the radial surface of the metacarpal heads.
4. Associated manifestations: Chondrocalcinosis (chondrocalcinosis), which is most clearly visualized in the wrist joint area.

Imaging patterns of renal pathologies: cysts and nephrocalcinosis

Radiological evaluation of the renal parenchyma allows differentiation of metabolic and structural disorders.

Nephrocalcinosis (nephrocalcinosis) is characterized by the deposition of calcium salts in the cortical or medullary substance. In mild cases, changes may be absent on radiographs. On ultrasound, a typical sign is hyperechoic renal parenchyma with posterior acoustic shadowing. High-density areas of the parenchyma are visualized on CT.

Cystic syndromes range from benign conditions to pathologies with a high oncogenic risk:

• Lithium-induced disease: Bilateral microcysts (1–2 mm) in the cortex and medulla against the background of long-term lithium therapy.
• Acquired cystic disease: Occurs in end-stage renal failure (atrophic kidneys, 3 or more cysts).
• Genetic syndromes: In von Hippel-Lindau disease (up to 75% of patients) and tuberous sclerosis, the presence of cysts is associated with a high risk of renal cell carcinoma (reaching 70% in VHL disease). Multicystic dysplastic kidney (MCDK) is characterized by unilateral involvement with ureteral atresia.

Imaging in urolithiasis

Urolithiasis manifests as flank pain and hematuria. The primary diagnostic method is non-contrast CT, which allows not only accurate stone measurement but also assessment of complications (hydronephrosis, calyceal rupture). The likelihood of spontaneous stone passage decreases sharply when the size exceeds 10 mm.

Differentiation of calculi by attenuation and etiology:

• Calcium (75–80%): Radiopaque. Develop in hyperparathyroidism, medullary sponge kidney.
• Struvite: Radiopaque. Form in infections (urease-producing flora) and high urine pH; capable of rapidly forming staghorn calculi.
• Uric acid: Formed under low urine acidity and low diuresis (risk factors include gout, diabetes, high BMI). Amenable to dissolution by urine alkalinization.
• Cystine: Less dense, typical for pediatric patients in the setting of genetic disorders.

For precise stone differentiation, dual-energy CT (DECT) is used. The method is based on the principle that the linear X-ray attenuation coefficient depends on the mass density of the substance and photon energy. Using two different energies makes it possible to distinguish materials that have the same density on standard CT (e.g., calcifications and urates).

Class and exam questions

What else to study on this topic

• Bosniak classification of renal cysts and the pseudocontrast effect on multidetector CT.
• ACR appropriateness criteria for indeterminate renal masses and management of incidental CT findings.
• The role of imaging in diagnosing specific pathogens of community-acquired pneumonia.
• Application of fetal ultrasound for prenatal detection of congenital renal anomalies.
• Dual-energy CT and ultrasound in the differential diagnosis of gout and seronegative arthritides.

Other topics in the section "Diagnostic Radiology of the Abdominal Organs"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.