Etiology and pathogenesis of uterine hyperplastic processes
The development of hyperplastic processes is based on the hormonal theory. The pathogenesis is associated with impaired excretion and metabolism of estrogens, as well as changes in the balance of their fractions: estrone and estradiol dominate in the follicular phase, and estriol in the luteal phase.
The increase in uterine mass occurs due to hyperplasia (triggered by estrogens) and hypertrophy of smooth muscle cells. Progesterone also plays a key role: in the luteal phase, it increases mitotic cell activity and induces growth factors. Cell hypertrophy is possible only under the combined action of high concentrations of estradiol and progesterone (similar to the processes during pregnancy).
In altered tissues, the number of sex steroid receptors is significantly higher than normal. Disruption of hormone metabolism causes autocrine stimulation of cells, mediated by insulin-like growth factors (IGF-I and II).
Additional risk factors:
- Changes in immune reactivity (against the background of chronic infections).
- Impaired microcirculation and pelvic hemodynamics.
- Hereditary predisposition.
- Embryonic factor (node rudiments can form intrauterine and grow for years under the action of ovarian hormones).
- Presence of inflammatory infiltrates and foci of endometriosis around which growth zones form.
Morphology and classification of nodes
Depending on the ratio of muscular and connective tissue, hyperplastic formations are divided into myomas, fibromas, and fibromyomas.
According to morphogenetic criteria, the following are distinguished:
- Simple myomas: develop as benign muscle hyperplasia.
- Proliferating myomas: exhibit signs of a true benign tumor, characterized by rapid growth (found in 25% of patients). The number of pathological mitoses in them does not exceed 25%.
Classification by localization:
- Submucosal: grow into the uterine cavity.
- Subserosal: grow towards the peritoneal cavity.
- Interstitial (intramural): are located within the thickness of the middle myometrial layer.
- Intraligamentous: split the leaves of the broad ligament of the uterus.
Submucosal and subserosal nodes are further divided into types depending on the volume of the intramural component: Type 0 (pedunculated, 0%), Type I (less than 50%), and Type II (50% or more).
Clinical presentation and complications
Symptoms directly depend on the location of the hyperplastic nodes.
Submucosal localization: Manifests as prolonged and heavy menstruation with clots (menorrhagia), as well as intermenstrual bleeding (metrorrhagia), which rapidly leads to anemia. Patients are bothered by dragging and cramping pain. In type 0, spontaneous expulsion («birth») of the node is possible, accompanied by intense contractions. It often leads to infertility and pregnancy loss.
Subserosal localization: Small nodes are asymptomatic. As they grow, they cause discomfort and pain radiating to the lower back or leg. With pedicle torsion or tissue necrosis, an «acute abdomen» picture develops. Large nodes compress adjacent organs: anterior growth causes dysuria and acute urinary retention, posterior growth causes defecation disorders, and ureteral compression leads to hydronephrosis.
Interstitial localization: Nodes reduce the contractile capacity of the myometrium. The main complaint is heavy menstruation. Anemia can occur even without cycle disruptions due to blood pooling in the enlarged uterus. With giant sizes (more than 20 weeks of pregnancy), inferior vena cava compression syndrome occurs in the supine position (shortness of breath, palpitations).
Instrumental diagnostics
Historically, X-ray metrography was used to detect submucosal nodes; however, today the gold standard is ultrasound diagnostics (echography) with an informativity of up to 95.7%.
Ultrasound semiotics:
- Nodes have a layered structure and are surrounded by a pseudocapsule (a zone of compacted myometrium).
- Homogeneous hyperechoic formations indicate the predominance of fibrous tissue.
- Hypoechoic inclusions indicate necrosis or cystic cavities.
- Hyperechoic zones with an acoustic shadow are a sign of calcification.
To assess blood flow, Doppler ultrasound is used. Qualitative assessment shows single blood flow in simple myoma and intensive blood flow in proliferating myoma. The quantitative indicator is the resistive index (RI):
- Fibromyoma: RI > 0.60
- Simple myoma: RI = 0.55–0.60
- Proliferating myoma: RI = 0.50–0.55
- Node necrosis: RI < 0.44
- Uterine sarcoma: RI < 0.40 (arteriovenous shunts are formed).
For precise topography of submucosal nodes, 3D ultrasound is used, which also allows simultaneous diagnosis of concomitant endometrial hyperplasia.
Briefly: answers to topical questions
What are the histological types of endometrial hyperplasia according to the WHO classification?
According to the WHO classification, three main types of endometrial hyperplastic processes are distinguished:
- endometrial polyps;
- endometrial hyperplasia — simple and complex;
- hyperplasia with cellular atypia — simple and complex.
In domestic practice, the terms «atypical hyperplasia» and «adenomatosis» are used as synonyms. Atypical hyperplasia is subdivided into mild, moderate, and severe degrees.
What methods are used for morphological verification of the diagnosis of endometrial hyperplasia?
For morphological verification of the diagnosis of endometrial hyperplasia, methods of studying endometrial material are used:
- histological examination of uterine mucosal scrapings — the definitive diagnostic method; the material is obtained by fractional diagnostic curettage;
- hysteroscopy combined with curettage — performed to clarify the nature and localization of the pathology, as well as visual control of the completeness of pathological tissue removal;
- endometrial aspiration biopsy — used as a screening method for studying the aspirate from the uterine cavity and to monitor the effectiveness of hormone therapy in hyperplastic processes.
What groups of drugs are used for the conservative treatment of endometrial hyperplasia?
Hormone therapy is used for the conservative treatment of endometrial hyperplasia. The following drug groups and administration methods are used:
- Progestogens — used for systemic administration in a continuous regimen.
- Progestin-releasing intrauterine contraceptives — used for local hormone administration (levonorgestrel-releasing intrauterine system).
Hormone therapy is prescribed strictly after hysteroscopy, fractional diagnostic curettage, and obtaining the results of histological examination. In case of disease relapse, continuation of therapy with higher doses of drugs is possible.
The types of submucosal and subserosal nodes are easy to remember by the proportion of the intramural component: type 0 — 0% (pedunculated), type I — less than 50%, type II — 50% or more.
Class and exam questions
How to distinguish submucosal myoma from an endometrial polyp on ultrasound?
The sound conductivity of submucosal myoma nodes is higher than that of endometrial polyps. Intrauterine echography and 3D ultrasound are used for the most accurate differential diagnosis.
What are the criteria for malignant transformation (sarcomatous degeneration)?
Warning signs include the detection of more than 70% pathological mitoses, cellular atypia, and nuclear pleomorphism. According to Doppler sonography, signs of sarcoma include atypical vascularization and a decrease in the resistance index (RI) below 0.40.
Why does anemia occur with interstitial myoma even in the absence of bleeding?
In the absence of menstrual irregularities, anemia can develop due to the chronic pooling (accumulation) of a large volume of blood in the uterine vascular network, which is significantly enlarged by myoma nodes.
What else to study on this topic
- The role of insulin-like growth factors (IGF-I and II) in the autocrine stimulation of the myometrium.
- Differential diagnosis of the causes of an "acute abdomen" in subserosal node necrosis.
- Prognosis of interstitial node growth (centripetal, centrifugal, and central growth).
- Inferior vena cava compression syndrome: pathogenesis and management tactics for patients.
- Histological differences between simple and proliferating leiomyoma.
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