[A case of spindle cell carcinoma of the stomach presenting with hematochezia and weight loss due to fistulous tract formation with colon].

Spindle cell carcinoma (SpCC) is a rare tumor consisting of spindle cells which express cytokeratin. Despite recent advances in immunohistochemical and genetic studies, precise histogenesis of SpCC is still controversial and this tumor had been referred to with a wide range of names (in the past): carcinosarcoma, pseudosarcoma, sarcomatoid carcinoma, pseudosarcomatous carcinoma, and collision tumor. Recently, the authors experienced an extremely rare case of SpCC arising from the stomach. A 64-year-old male presented with unintended weight loss and hematochezia. Endoscopic examination revealed a fistulous tract between the stomach and the transverse colon which was made by direct invasion of SpCC of the stomach to the colon. Histologically, the tumor was positive for both vimentin and cytokeratin but negative for CD117, CD34, actin, and desmin. Herein, we report a case of SpCC arising from the stomach that formed a fistulous tract with the colon which was diagnosed during evaluation of hematochezia and weight loss.