Heterotopic pancreas in the gallbladder: The importance of an uncommon condition

A 58-year-old man with a chief complaint of epigastralgia was admitted to our hospital. Physical examination disclosed a large, firm mass in the right hypochondrium. Abdominal computed tomography comfirmed thickening of the gallbladder wall and a 15 × 8 cm mass occupying almost all of the right lobe and medial segment of the liver. With a preoperative diagnosis of malignant gallbladder tumor infiltrating the liver, right hepatic trisegmentectomy was performed. Histopathologic examination showed atypical cells with small round to oval nuclei and sparse eosinophilic cytoplasm, proliferating in a solid and focal nesting pattern. Near this small cell proliferation was a focus of tubular adenocarinoma that showed a zone of transition from the small cell neuroendcrine pattern. The small cells demonstrated immunohistochemical reactivity for chromogranin A. Electron microscopy disclosed neurosecretory granules 150 nm in diameter, representing dense round core vesicles, confirming a neuroendocrine cell linage. The patient was diagnosed with neuroendocrine cell carcinoma combined with adenocarcinoma of the gallbladder. Tumor recurrence became evident 3 months after surgery, and he died 4 months after surgery.