Small Cell Neuroendocrine Carcinoma of the Gallbladder: Natural History and Therapeutic Challenges.

Small cell neuroendocrine carcinoma (SNEC) of the gallbladder is an extremely rare and aggressive primary gallbladder malignancy with poor prognosis. A 65-year-old woman presented with constipation followed by jaundice and right upper quadrant pain one month later. Imaging revealed a porta hepatis mass with hepatic and duodenal involvement. Fine needle aspiration confirmed metastatic small cell carcinoma positive for synaptophysin, chromogranin, and CDX2 with Ki-67 >70%. Despite planned platinum-etoposide chemotherapy, rapid disease progression with inferior vena cava invasion precluded treatment. The patient died 13 weeks after symptom onset. This case demonstrates the aggressive natural history of gallbladder SNEC. Early tissue diagnosis and prompt platinum-etoposide chemotherapy initiation while performance status permits remain critical for meaningful survival benefit.