Which marker is used as a downstream surrogate marker for HPV-driven transformation in cervical pathology?

• A. Ki-67
• B. p16
• C. ER
• D. CK7

Answer: (B)

The main idea is that high‑risk HPV drives transformation by inactivating the RB pathway through the E7 oncoprotein, and this leads to upregulation of p16. Immunostaining for p16 becomes strong and diffuse in HPV-driven cervical lesions, making it a reliable downstream surrogate marker for HPV activity. In other words, p16 overexpression reflects the RB inactivation caused by HPV, tying the staining pattern directly to HPV-driven neoplasia.

Ki-67 is a general proliferation marker and can be elevated in many conditions, so it lacks the HPV-specific signal. ER and CK7 indicate tissue type or differentiation and do not specifically signal HPV-driven transformation in the cervix.