A 28-year-old presents with an ovarian mass showing calcifications on ultrasound. Histopathology reveals nests of cells with central keratinization (Rosenthal fibres absent), inter-cellular bridges, and areas of squamous differentiation. Serum AFP is normal, βhCG is normal. What is the most likely diagnosis?
- A Mature cystic teratoma with malignant transformation (squamous cell carcinoma) ✓
- B Brenner tumour (transitional cell type)
- C Metastatic squamous cell carcinoma to ovary
- D Granulosa cell tumour (adult type)
Explanation
Malignant transformation (MT) occurs in approximately 1–3% of mature cystic teratomas (dermoid cysts), most commonly to squamous cell carcinoma (SCC) arising from the epithelial lining. The finding of squamous nests with intercellular bridges and keratinization within an ovarian mass that contains calcifications (consistent with a dermoid) strongly favours SCC arising in a dermoid. SCC arising from MT typically has normal tumour markers (AFP, βhCG, CA-125 may be elevated later). Brenner tumours show transitional/urothelial-type epithelium (Walthard cell nests) without squamous maturation nests. Granulosa cell tumours show Call-Exner bodies and inhibin positivity.
Reference: Shaw's Textbook of Gynaecology, 17th ed.
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