Primary squamous cell carcinoma of the stomach: a case report with immunohistochemical and molecular biologic studies.

Primary squamous cell carcinoma (SCC) of the stomach is an extremely rare tumor and its pathogenesis is still unknown. We report a case of SCC of the stomach in a 69-year-old man. The patient's stomach contained an area of SCC surrounded by squamous metaplasia. To our knowledge, this is the first reported study to have investigated the pathogenesis of this tumor type by immunohistochemistry, liquid hybridization assay for human papilloma virus (HPV) infection, and polymerase chain reaction for Epstein-Barr virus (EBV) infection. These tests yielded proof of EBV infection in surgical specimens of the tumor. Therefore, we suggest that EBV infection may be involved in the pathogenesis of SCC arising in the stomach.