Which marker is included in the IHC panel for primary ovarian carcinoma?

• A. NKX3.1
• B. WT1
• C. CD10
• D. PAX2

Answer: (B)

Immunohistochemistry uses markers to identify tumor origin, and WT1 is a nuclear marker strongly associated with serous ovarian carcinomas. Including WT1 in the panel helps confirm a primary ovarian serous carcinoma and distinguish it from metastases or other ovarian histologies that are WT1-negative.

NKX3.1 points toward prostatic or urothelial differentiation, which would suggest a metastasis or non-ovarian origin rather than a primary ovarian tumor. CD10 can be positive in other gynecologic and renal/soft tissue lesions, so it’s not specific for primary ovarian carcinoma. PAX2 is more informative for renal or Müllerian-derived lesions in different contexts and is not the standard marker used to identify primary ovarian serous carcinoma.