Case report: A challenging case of stage IVB mixed neuroendocrine-non-neuroendocrine neoplasm of the gallbladder treated with extended radical resection including portal vein reconstruction.

BACKGROUND

Gallbladder cancer is a highly lethal biliary tract malignancy. Among them, mixed neuroendocrine-non-neuroendocrine neoplasms (MiNEN), particularly those containing large cell neuroendocrine carcinoma (LCNEC) components, are extremely rare and highly aggressive. Due to its low incidence and insidious symptoms, reports on the clinicopathological characteristics and optimal treatment strategies for such tumors are very limited, with diagnosis primarily relying on pathology and immunohistochemistry.

CASE PRESENTATION: A 78-year-old female was incidentally found to have a gallbladder mass during a routine physical examination, accompanied by a significantly elevated carcinoembryonic antigen (CEA) level (84.09 ng/ml). MRI imaging indicated gallbladder malignancy with multiple liver and hilar lymph node metastases. The patient underwent extended radical surgery, including partial hepatectomy, pancreaticoduodenectomy, and partial portal vein resection with anastomosis. Postoperative pathology and immunohistochemistry confirmed a mixed adenoma-large cell neuroendocrine carcinoma of the gallbladder with multiple metastases. Immunohistochemistry showed Syn (+), CK19 (+), Ki-67 (+) approximately 80%, INSM1 (+), and CgA (+) approximately 10%. All surgical margins were negative. The patient recovered well postoperatively.

CONCLUSION

This case report describes a rare case of locally advanced mixed adenoma-large cell neuroendocrine carcinoma of the gallbladder in primary hospital. Achieving negative margins through aggressive extended radical surgery may be a feasible treatment option in carefully selected patients; however, the oncological benefit remains to be validated. It emphasizes the critical role of multidisciplinary collaboration in diagnosis and treatment and adds new data to the limited literature on this rare disease.