Signet ring cell carcinoma of the non-ampullary duodenum: A case report.

We describe a case of signet ring cell carcinoma of the non-ampullary duodenum in an 86-year-old woman. Endoscopic examination revealed a fungating lesion (Borrmann classification; type 2) on the anterior wall of the descending duodenum (second part). Pylorus-preserving pancreaticoduodenectomy and lymphadenectomy were performed. The tumor (pT3 and pN0) was predominantly composed of signet ring cells, characterized by a central, optically clear, globoid droplet of cytoplasmic mucin with an eccentrically placed nucleus. The cells were positive for periodic acid Schiff with diastase and Alcian blue pH 2.5. On immunohistochemical examination, MUC-5AC, MUC-2 and CDX2 were diffusely positive, and MUC-6 was negative in the tumor cells, which consisted of mixed gastric foveolar and intestinal phenotypes. Cytokeratin 7 was focally positive, but cytokeratin 20 was negative. Nuclear staining of p53 was diffusely and weakly positive. Signet ring cell carcinoma occurring in the non-ampullary duodenum might derive from duodenal goblet cells with MUC-5AC expression.