Mucinous ovarian tumours of intestinal type are most important to distinguish from metastatic colorectal carcinoma. Which immunohistochemical marker combination best identifies a primary ovarian mucinous tumour versus Krukenberg tumour?

• A CK7+/CK20− ✓
• B CK7−/CK20+
• C CK7+/CK20+ with CDX2 positive
• D WT-1 positive, PAX8 positive

Explanation

Primary ovarian mucinous tumours typically express CK7 and are CK20-negative (CK7+/CK20−). Metastatic colorectal carcinoma (Krukenberg from colon) shows the reverse pattern: CK7−/CK20+ with CDX2 positivity (intestinal marker). WT-1 and PAX8 are markers of serous ovarian tumours. This IHC distinction is critical because ovarian mucinous carcinoma may warrant primary cytoreductive surgery, while bilateral mucinous tumours are most often metastatic and warrant GI workup.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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