A case of classical carcinoid tumor of the gallbladder: review of the Japanese published works.

A 58 year-old man was admitted to Kimitsu Chuo Hospital complaining of epigastralgia. Abdominal ultrasound and computed tomography revealed a polypoid lesion at the neck of the gallbladder. Given the pre-operative diagnosis of gallbladder carcinoma, we resected the gallbladder along with the extrahepatic bile duct. There was a papillary tumor (25 x 16 mm) at the neck of the gallbladder. Histopathological examinations showed a subserosal nodular proliferation of uniform small tumor cells. Grimelius staining was slightly positive and Fontana-Masson staining was negative. Most of the tumor cells stained positively for chromogranin A and neuron-specific enolase (NSE), and some of the tumor cells were positive for pancreatic polypeptide. The presence of neurosecretory intracytoplasmic granules was proven ultrastructurally. It was diagnosed as a classical carcinoid tumor of the gallbladder. We reviewed the Japanese reported cases and discussed the difference in clinicopathological findings between classical and atypical carcinoid tumors of the gallbladder. Classical carcinoids of the gallbladder have neither a metastatic nor invasive character, and an extremely favorable prognosis compared with atypical carcinoids. The difference in character between classical and atypical carcinoids of the gallbladder is thought to be derived from their histogenetic origin.