p16 Expression Correlates with Invasive Ocular Surface Squamous Neoplasms in HIV-Infected Mozambicans

Background: p16 immunohistochemistry is widely used to diagnose human papillomavirus (HPV)-related squamous neoplasms of cervix, anogenital, head, and neck tissues. The incidence of these HPV-related squamous neoplasms is markedly increased in the HIV-infected population. Ocular surface squamous neoplasia (OSSN) is also more common in HIV-infected patients. However, the expression pattern of p16 in OSSN among HIV-infected patients is unclear. Here, we examined the expression of p16 in OSSN surgical excisions collected from a large HIV-infected cohort from ­Mozambique. Methods: OSSN surgical tissue specimens were collected from 75 Mozambican patients. Formalin-fixed, paraffin-embedded tissue blocks from these OSSNs were sectioned, stained with hematoxylin and eosin (H&E), and p16 expression by immunohistochemistry. H&E slides were reviewed to determine if OSSNs were noninvasive conjunctival intraepithelial neoplasms or invasive squamous cell carcinomas (SCC). Cases were classified as p16 positive or negative based on diffuse nuclear and cytoplasmic expression of p16 in neoplastic cells. Results: p16 positivity was found in a minority of OSSN cases (14/75). p16 positivity was significantly associated with the invasive SCC type of OSSN in HIV-infected patients (p value of 0.026). Conclusions: The majority of OSSNs in our HIV-infected cohort do not express p16. However, those cases that are p16-positive are significantly more likely to be the invasive SCC form of OSSN. We propose that p16 expression may identify more aggressive OSSNs in HIV-infected populations.