Small cell neuroendocrine carcinoma of the ampulla of Vater with foci of squamous differentiation: a case report.

A 54-year-old woman with obstructive jaundice was found to have a 4-cm ulcerated, elevated tumor, located at the papilla of Vater by endoscopy and radiographic investigation. Based on a clinical diagnosis of carcinoma of the ampulla of Vater, a pylorus-preserving pancreaticoduodenectomy was performed. The histologic appearance of the lesion was identical to extrapulmonary small cell carcinoma, with diffuse proliferation of small, spindle-shaped, atypical tumor cells with numerous mitoses. Neuroendocrine differentiation was demonstrated by immunoreactivity with neuron-specific enolase (NSE) and Leu-7, and by the presence of dense core granules ultrastructurally. The tumor was composed mainly of small cell neuroendocrine carcinoma, and partially of an area of squamous differentiation, showing transition from one to the other. Histopathologic investigation disclosed direct invasion deep to the lamina propria, and infiltration of the pancreatic parenchyma, duodenum, and bile duct. Lymph node metastases were present in the superior pancreaticoduodenal chain. The patient died of liver metastases 8 months later. As in previously reported cases of small cell neuroendocrine carcinoma of the ampullary region, the present case showed extremely aggressive clinical behavior with early metastases resulting in fatal outcome.