A 58-year-old postmenopausal woman with a long history of endometriosis presents with a pelvic mass. Histology of the resected ovarian tumour shows sheets of polygonal cells with abundant clear cytoplasm and hobnail cells lining glandular spaces. Which statement about this tumour is correct?
- A It frequently harbours ARID1A mutations and carries a poorer prognosis than high-grade serous carcinoma at equivalent stage ✓
- B It is highly sensitive to platinum-based chemotherapy
- C It typically presents with markedly elevated CA-125 above 1000 U/mL
- D It arises through the same p53 mutation pathway as high-grade serous carcinoma
Correct answer: A. It frequently harbours ARID1A mutations and carries a poorer prognosis than high-grade serous carcinoma at equivalent stage
Explanation
Clear cell carcinoma of the ovary is strongly associated with endometriosis and characterised by ARID1B mutations, clear and hobnail cells, and platinum resistance, giving a worse prognosis than high-grade serous carcinoma when matched for stage. It does not follow the TP53-mutated high-grade serous pathway. CA-125 is often normal or only mildly raised in clear cell tumours, which is why it cannot be used to exclude this diagnosis.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
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