Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea.
Neuroendocrine tumor (NET) of the gallbladder (GB) (GB-NET) is a very rare condition, representing 0.5% of all NET cases. Here, we report a case of GB-NET with peritoneal metastasis. A 55-year-old man was admitted to our institution for workup for an abdominal distension, which developed 5 weeks ago. Computed tomography (CT) of his abdomen showed ascites and an 18-cm heterogeneous enhancing mass surrounding the GB and invading the liver. Needle biopsy of the GB revealed poorly differentiated sheets of neoplastic cells with hyperchromatic nuclei and indistinct cytoplasm (