Which marker is included in the IHC panel for primary ECX adenocarcinoma?

• A. ER
• B. p16
• C. PSMA
• D. CA-125

Answer: (B)

The main idea here is using p16 as a surrogate marker for HPV involvement in endocervical-type adenocarcinomas. When high‑risk HPVs drive these tumors, the E7 oncoprotein inactivates RB, which leads to strong, diffuse overexpression of p16. This pattern helps confirm HPV-related endocervical adenocarcinoma and distinguishes it from other tumors that might look similar but aren’t HPV-driven. The other markers don’t fit this context: ER is tied to hormone receptor status in breast and some gynecologic tumors, PSMA is associated with prostate/some other tumors, and CA‑125 is a general ovarian/peritoneal marker and not specific for HPV-related endocervical cancer. Therefore, p16 is the most relevant marker to include in the panel.