Mixed squamous – neuroendocrine carcinoma of the gallbladder: A case report of a rare pathological entity

Gallbladder cancers are the most common biliary tract malignancies in the world. Adenocarcinoma constitutes the most common histology in gallbladder cancer. Neuroendocrine neoplasms of the gallbladder account for about 0.5% of all neuroendocrine neoplasms and 2.1% of all gallbladder tumors. They are rare tumors and present with non-specific symptoms such as abdominal pain, weight loss, anorexia, and obstructive jaundice, and, therefore, are often challenging to diagnose and treat. Mixed neuroendocrine-non-neuroendocrine neoplasm is a subtype of neuroendocrine neoplasm. To add to the literature, we report a rare case of a patient who presented with pain in the abdomen and non-bilious vomiting and was diagnosed with mixed neuroendocrine-non-neuroendocrine gallbladder cancer, identified by immunohistochemistry, and treated with palliative chemotherapy. Due to non-specific symptoms, patients may present at an advanced stage. Further, immunohistochemistry may assist in clinching the diagnosis.