Non-neoplastic lesions: cysts and PCOS
Atresia of tertiary follicles can lead to their expansion and cyst formation.
- Follicular cyst: Macroscopically, it has a smooth, light-gray inner surface, and the lumen is filled with clear, pale fluid. Microscopically, the wall consists of granulosa and theca cells. Upon regression, it transforms into a corpus fibrosum.
- Corpus luteum cyst: Characterized by a scalloped, bright-yellow rim (luteinized cells). The outcome of its regression is a corpus albicans.
Polycystic ovary syndrome (PCOS) is characterized by multiple cystically dilated follicles. The disease develops against the background of elevated luteinizing hormone (LH), hyperandrogenemia, obesity, and hyperinsulinemia (with hyperprolactinemia in 25% of cases). Clinically, this manifests as infertility, anovulation, hirsutism, and acne. Morphology of PCOS: The ovaries are enlarged 2 times or more, with a whitish-gray surface. Microscopically, the cortical layer is fibrotic and thickened, with numerous atretic follicles visible. The main distinguishing feature is the absence of corpora lutea and corpora albicantia. Treatment is based on hormone therapy.
Stromal hyperplasia — proliferation of stromal cells (often in peri- and postmenopausal women, associated with obesity). If combined with cell luteinization, the condition is termed stromal hyperthecosis (revealing polygonal cells with vacuolated eosinophilic cytoplasm).
Epithelial ovarian tumors
This group of neoplasms is distinguished by a wide variety of histological structures.
- Serous tumors: Characterized by fibrous tissue proliferation with small cysts. The malignant variant (serous cystadenocarcinoma) features papillary structures, pronounced cellular atypia, and deep invasion into the ovarian tissue. Psammoma bodies (lamellated calcifications) are often found in the tissue.
- Mucinous tumors: Can reach giant sizes. Benign mucinous cystadenoma is a multilocular cyst with clear mucus, lined by tall non-ciliated epithelium. Upon malignant transformation (cystadenocarcinoma), solid areas and hemorrhages appear; the epithelium becomes stratified, loses mucus, and invades the capsule. A specific complication is pseudomyxoma peritonei, in which jelly-like masses accumulate in the abdominal cavity, causing adhesive intestinal obstruction. Its development does not depend on the tumor's grade of malignancy.
- Endometrioid tumors: In most cases, they develop de novo from the surface epithelium (less frequently from foci of endometriosis). Usually malignant, they are microscopically identical to endometrial adenocarcinoma.
- Clear cell tumors: Rare malignant neoplasms composed of large cells with abundant clear cytoplasm.
- Brenner tumor: Has a biphasic structure — fibroma-like stroma and nests of transitional-type epithelium (resembling urothelium). In its malignant variant, it contains transitional cell carcinoma structures.
Germ cell tumors
Germ cell tumors may consist of derivatives of embryonic layers with varying degrees of maturity.
- Mature teratoma (dermoid cyst): Develops from 2–3 germ layers, but ectoderm dominates. Found in patients aged 12–70 years. It is a unilocular cyst containing sebaceous material and hair, with stratified squamous epithelium, teeth, cartilage, and bone tissue in its wall.
- Immature teratoma: A rare (3% of teratomas), aggressive tumor. Mean age is 18 years. Macroscopically, it is a solid, nodular, pinkish-gray mass with areas of necrosis. Microscopically, it consists of immature tissues, among which the neural tube predominates. Characterized by rapid growth and metastasis.
- Monodermal teratomas: Struma ovarii (composed of normal thyroid tissue) and carcinoid (resembling GI tumors, can cause carcinoid syndrome, rarely malignant).
- Dysgerminoma: A tumor composed of large cells rich in glycogen (resembling primordial follicle cells). The stroma is infiltrated by lymphocytes. Occurs at ages 20–40. Despite being malignant, it has a less aggressive clinical course, metastasizes late, and responds well to radiotherapy.
- Yolk sac tumor (endodermal sinus tumor): A malignant neoplasm derived from multipotent cells. It forms extraembryonic structures.
Briefly: answers to topical questions
What are the histological types of epithelial ovarian tumors according to the WHO classification?
According to the WHO histological classification, the following types of epithelial tumors (surface epithelial-stromal tumors) are distinguished:
- Serous tumors — simple, papillary (coarsely papillary), and papillary cystadenomas.
- Mucinous tumors — pseudomucinous cystadenoma.
- Endometrioid tumors — microscopically similar to endometrial adenocarcinoma.
- Clear cell tumors — a rare variant of surface epithelial tumors.
- Brenner tumors — have a biphasic structure comprising stroma and transitional-type epithelium.
- Ovarian cancer.
Which tumor markers are used for the differential diagnosis of ovarian germ cell tumors?
For the differential diagnosis of ovarian germ cell tumors, the levels of specific tumor markers are evaluated:
- Alpha-fetoprotein (AFP) — produced by the yolk sac tumor; also elevated in embryonal carcinoma, polyembryoma, and in approximately one-third of immature teratomas.
- Beta-human chorionic gonadotropin (β-hCG) — characteristic of choriocarcinoma; also elevated in embryonal carcinoma and polyembryoma.
- Lactate dehydrogenase (LDH) — elevation above reference values is characteristic of ovarian germ cell tumors.
A combined elevation of AFP and β-hCG is characteristic of embryonal carcinoma and polyembryoma. CA-125 and HE4 markers have no diagnostic value in germ cell tumors.
What forms of gestational trophoblastic disease exist?
Gestational trophoblastic disease includes benign and malignant forms:
- Simple hydatidiform mole (complete or partial) — a benign form with a risk of malignancy.
- Invasive mole — a malignant trophoblastic tumor.
- Choriocarcinoma (chorioepithelioma) — a malignant tumor developing from trophoblastic epithelium.
- Placental site trophoblastic tumor — a malignant form.
- Epithelioid trophoblastic tumor — a malignant form.
What are the microscopic differences between a complete and a partial hydatidiform mole?
The microscopic differences between a complete and a partial hydatidiform mole lie in the extent of villous involvement, the degree of trophoblastic proliferation, and the presence of fetal elements.
| Sign | Complete hydatidiform mole | Partial hydatidiform mole |
|---|---|---|
| Chorionic involvement | Changes involve the entire chorion (the entire placental tissue is affected) | Changes involve only part of the chorion |
| Villous edema | Diffuse villous edema | Vesicular (edematous) villi are distributed focally |
| Trophoblastic proliferation | From mild to pronounced | Local trophoblastic proliferation is weakly expressed |
| Fetal elements | Completely absent | Mandatory presence (among areas of normal placental tissue) |
Class and exam questions
What is the main microscopic difference in the ovaries in PCOS?
Multiple cystic atretic follicles are found in the cortical layer, while corpora lutea and corpora albicantia are completely absent.
What are the dangers of pseudomyxoma peritonei development?
The accumulation of gelatinous masses causes mechanical dysfunction of organs and the formation of severe adhesions, which can lead to acute intestinal obstruction.
What is the prognosis for ovarian dysgerminoma?
Despite its malignant nature, the prognosis is relatively favorable because the tumor metastasizes late and responds well to radiotherapy.
What else to study on this topic
- Pathogenetic mechanisms of polycystic ovary syndrome development
- Histological differential diagnosis of epithelial carcinomas
- Manifestations of carcinoid syndrome in specialized teratomas
- Molecular genetic features of immature teratomas
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