Adenocarcinoma of the minor duodenal papilla with intraepithelial spread to the pancreatic duct.

It is extremely rare to encounter tumors arising exclusively in the minor duodenal papilla. We report a 60-year-old male patient with a polypoid type of adenocarcinoma of the minor papilla. Preoperative examinations, including computed tomography (CT) and magnetic resonance cholangiopancreatography (MRCP), suggested pancreas divisum and showed a series of stones in the dorsal pancreatic duct. The patient underwent subtotal stomach-preserving pancreaticoduodenectomy (SSpPD). On histology, an adenocarcinoma was located in the minor papilla, which was limited to the mucosa, without invasion of the duodenum, sphincter muscles of the minor papilla, or the underlying pancreas. The carcinoma cells, together with dysplastic and hyperplastic epithelium of the pancreatic duct, extended peripherally within the pancreatic duct. No cystic dilatation of the pancreatic duct was observed. The ventral pancreatic duct was short and narrow; there was evidence of chronic pancreatitis in the dorsal pancreas, whereas the ventral pancreas was almost normal, suggesting the existence of pancreas divisum. Although it is well known that adenocarcinoma of the duodenal papilla is sometimes accompanied by intraepithelial spread in the pancreatic duct, an adenocarcinoma arising in the minor papilla in this case with pancreas divisum was more extended than our thoughts.