Pathology of Invasive and Intraepithelial Penile Neoplasia

Since 1995 it has been known that tumors harboring human papillomavirus (HPV) preferentially show basaloid or condylomatous histological features, while HPV-negative tumors have a different morphology. New classification models separate subtypes of penile squamous cell carcinomas in two groups, non-HPV- and HPV-related. It is purported that HPV-related tumors have better prognosis. Other features such as inflammatory cell-rich medullary, clear-cell, and lymphoepithelioma-like patterns are also strong predictors of the presence of HPV. These tumors are morphologically distinctive and with some experience, pathologists may recognize them after routine hematoxylin and eosin staining. Occasionally, p16 immunostaining may aid in differential diagnosis. The gold standard for HPV detection is polymerase chain reaction, but this technique is expensive and not available in most pathology laboratories. In situ hybridization is useful and p16 immunostaining can detect HPV in approximately 85% of cases. There is correlation between morphology and outcome. PATIENT SUMMARY: This mini review provides an overview of the latest classification for penile invasive carcinoma and penile intraepithelial neoplasia.