Gallbladder neuroendocrine tumors (GB-NETs) and gallbladder neuroendocrine carcinomas (GB-NECs) are rare forms of neuroendocrine neoplasms (NENs). Most GB-NENs present as incidental findings or as gallbladder polyps in the course of investigation of nonspecific symptoms such as upper abdominal pain and nausea. Given the rarity of GB-NENs, only a few small case series are currently available describing this entity, and even fewer guiding consensus on standard treatment and the role of adjuvant therapy. We present the case of a 65-year-old South American female referred for a chronic history of intermittent post-prandial epigastric pain, bloating, nausea, and occasional diarrhea. Pancreaticobiliary maljunction with dilation was present and she was diagnosed with primary gallbladder large cell neuroendocrine carcinoma (GB-LCNEC) mixed with a minor component of gallbladder adenocarcinoma.