Paper II
Question
Dysgerminoma ovary
Answer
Dysgerminoma is the most common malignant germ cell tumour of the ovary, and is the female counterpart of testicular seminoma.
- Age: Typically occurs in young women/adolescents (peak in 2nd–3rd decades).
- Gross: Solid, fleshy, grey-white to yellow-tan tumour with a lobulated cut surface; usually unilateral.
- Microscopy: Sheets and nests of large, uniform, polygonal cells with clear/glycogen-rich cytoplasm and centrally placed round nuclei with prominent nucleoli, separated by fibrous septa infiltrated by lymphocytes (and occasionally granulomas).
- Immunohistochemistry: Positive for PLAP (placental alkaline phosphatase), OCT3/4, and CD117 (c-KIT).
- Behaviour: Malignant but exquisitely radiosensitive and chemosensitive; has an excellent prognosis even when metastatic, with good response to treatment.
- Associations: May arise in dysgenetic gonads (e.g., gonadal dysgenesis with Y chromosome material) and may secrete hCG (causing mild elevation, especially if syncytiotrophoblastic giant cells are present) but does not typically secrete AFP (unlike yolk sac tumour, an important differential).