A 54-year-old woman with a 15-year history of laparoscopically proven endometriosis develops a 6 cm left ovarian mass. Staging laparotomy reveals disease confined to the ovary. Histology shows malignant epithelial cells with abundant clear cytoplasm arranged in tubulocystic patterns, hobnail nuclei protruding into lumina, and eosinophilic hyaline globules. Which histotype is this, and what paraneoplastic associations should be anticipated?

• A High-grade serous carcinoma, with hypertrophic osteoarthropathy
• B Clear cell carcinoma, with hypercalcaemia and venous thromboembolism ✓
• C Endometrioid carcinoma, with cerebellar degeneration
• D Mucinous carcinoma, with acanthosis nigricans

Explanation

Clear cell carcinoma arises from endometriotic epithelium, accounts for about 10 percent of ovarian cancers in Japan and around 5 percent elsewhere, and shows hobnail cells, tubulocystic architecture and hyaline globules. It is notoriously platinum resistant and carries the worst prognosis among stage-matched epithelial types. It is the epithelial ovarian histotype classically linked to paraneoplastic hypercalcaemia and thromboembolic events. High-grade serous carcinoma arises from the fallopian tube fimbriae and bears psammoma bodies instead.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.