Endoscopic ultrasound-guided fine-needle aspiration diagnosis of large cell neuroendocrine carcinoma of the gallbladder and common bile duct: report of a case.

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) allows a reliable and accurate diagnosis of neoplasms of the gallbladder and bile ducts. We report the cytopathologic findings of a case of large cell neuroendocrine carcinoma (LCNEC) of the gallbladder and extrahepatic bile ducts in a 67-year-old woman who presented with progressive abdominal pain and jaundice. EUS-FNA of the mass involving the common bile duct and of a porta hepatis lymph node showed abundant cellularity with tumor cells arranged singly and occasionally in tight and loose clusters and rosette-like structures in a background showing extensive necrotic debris. The tumor cells were predominantly plasmacytoid, showed a moderate amount of focally vacuolated cytoplasm and large round to oval hyperchromatic nuclei with prominent nucleoli, numerous mitoses, and apoptotic bodies. The differential diagnosis included poorly differentiated adenocarcinoma, lymphoma, melanoma, and poorly differentiated neuroendocrine carcinoma (NEC), large cell type. The tumor cells were strongly and diffusely positive for cytokeratin AE1/AE3, CD56, synaptophysin, and chromogranin and showed a very high proliferative fraction on Ki67 staining, supporting the diagnosis of a high-grade NEC. Due to the large size of the neoplastic cells, moderate amounts of cytoplasm and prominent nucleoli, a diagnosis of LCNEC was made on the EUS-FNA sample. Despite the prompt institution of chemotherapy, the patient died shortly thereafter and the diagnosis was confirmed at autopsy. This is to our knowledge the first case of LCNEC of the gallbladder and bile ducts diagnosed by EUS-FNA.