Pathology Characterization and Detection of Human Papillomavirus Type 16 in Rectal Squamous Cell Carcinomas.

Rectal squamous cell carcinoma (SCC) is a rare tumor with unresolved etiology. Human immunodeficiency virus-infected individuals and solid organ transplant recipients experience >30-fold and approximately 3-fold elevated rates of rectal SCC, respectively, suggesting immunosuppression plays a role.1 Human immunodeficiency virus-infected homosexual men have >60-fold higher rates of rectal SCC, similar to anal SCC. These patterns, which differ from the more common rectal adenocarcinoma (AdCA), raise the possibility of shared etiology between rectal and anal SCC, with human papillomavirus type 16 (HPV16) being a likely candidate.2.