Primary adenosquamous carcinoma of the colon: report of five cases.

Primary adenosquamous cell carcinomas (Ad-SCCs) of the colon and rectum are rare malignancies with a poor prognosis, in comparison to adenocarcinoma alone. Different roles of human papilloma virus (HPV) in its pathogenesis have been reported and the role of P16 in Ad-SCCs has not been explored. This report presents five cases of Ad-SCC of the colon to explore the clinicopathological features and the roles of P16, HPV 6/11, and 16/18. There was no confirmed evidence to support the relationship between the infection of HPV 6/11, 16/18, and pathogenesis of Ad-SCC of the colon. P16 overexpression was not related to HPV carcinogenesis and there might be another mechanism of P16 upregulation in Ad-SCC of the colon.