Colonic large cell neuroendocrine carcinoma obscured by an initial diagnosis of diverticulitis.

Large cell neuroendocrine carcinomas are rare and aggressive colorectal malignancies that have a dismal prognosis. We present the following case of a patient who presented with signs and symptoms of diverticulitis. After failure of medical management, surgical intervention revealed a poorly differentiated adenocarcinoma with a component of large cell neuroendocrine carcinoma.