Primary adenosquamous carcinoma of the colon.

Adenosquamous cell carcinoma (Ad-SCC) of the colon is rare. The pathogenesis of Ad-SCC is unclear, however, several hypotheses have been suggested. The clinical presentation and gross findings of Ad-SCC of the colon are similar to those of adenocarcinoma of the colon, but Ad-SCC has a more aggressive clinical course and a poorer prognosis. We report on two cases of Ad-SCC of the colon with obstruction; a collision-type Ad-SCC that has not only obstruction but also numerous hepatic metastases, and a composite-type Ad-SCC treated with left hemicolectomy followed by an adjuvant chemotherapy.