2026 Volume 40 Issue 2 Pages 198-205
We report a rare case of long-term complete response (CR) to chemotherapy in gallbladder large-cell neuroendocrine carcinoma (NEC). A 75-year-old woman with chronic hepatitis C achieved a sustained virological response after ledipasvir/sofosbuvir therapy and was followed for 9 years. She was referred to our hospital for a hepatic mass suspected as hepatocellular carcinoma. Contrast-enhanced computed tomography revealed a mass continuous from the gallbladder to the liver and multiple enlarged lymph nodes, and 18F-FDG PET/CT demonstrated avid uptake in these lesions. Percutaneous liver biopsy showed sheets of medium- to large-sized tumor cells with necrosis. The tumor cells were positive for synaptophysin and CD56, focally positive for chromogranin A, and negative for CK7, CK20, and CEA, with a Ki-67 index >50%, consistent with large-cell NEC of gallbladder origin. The patient received four cycles of etoposide plus cisplatin, resulting in CR of the primary and nodal lesions, which has been maintained for 30 months after chemotherapy. Although gallbladder NECs are often negative on somatostatin receptor scintigraphy, this case showed Krenning score 3 uptake concordant with SSTR2 expression on immunohistochemistry. This case suggests that even highly proliferative gallbladder NEC can retain somatostatin receptor expression and achieve durable CR with EP chemotherapy.
