[A case of large cell neuroendocrine carcinoma of the rectum]

A 77-year-old woman was referred to our hospital because of blood in feces and anal pain. Colonoscopy revealed a villous semicircular tumor in the rectum. A biopsy showed well-differentiated adenocarcinoma. Miles' operation was performed because of the persistence of anal pain and blood in feces. Histological and immunohistochemical analysis showed coexistent tubulovillous adenoma, tubulovillous adenocarcinoma, and large cell neuroendocrine carcinoma (LCNEC), which was positive for CD56, chromogranin A, and synaptophysin. Pathological examination revealed that most of the lesion was occupied by the LCNEC. The tumor was therefore diagnosed as LCNEC of the rectum. The patient underwent adjuvant chemotherapy with cisplatin (CDDP), irinotecan (CPT-11), and mFOLFOX6, but died because of LCNEC progression 10 months after the operation. LCNEC rarely occurs in the gastrointestinal tract; here we report a case of rectal LCNEC.