[A case of duodenal neuroendocrine carcinoma composed of small- and large-cell types].

A 78-year-old man underwent a detailed examination by upper gastrointestinal endoscopy for the complaint of epigastric pain. The examination revealed a hemicircumferential type 2 tumor in the descending duodenum. A subsequent biopsy led to a diagnosis of neuroendocrine carcinoma. Subtotal stomach-preserving pancreaticoduodenectomy was performed. The lesion was composed of small- and large-cell neuroendocrine carcinomas. The large-cell type component was positive for both caudal homeobox protein 2 and the cluster of differentiation 138, whereas the small-cell type component was negative for both. Our report may provide valuable information regarding the pathogenesis of neuroendocrine carcinoma.