LAUSR

Background Double primary cancers have a low incidence rate, and synchronous hepatocellular carcinoma and gallbladder adenocarcinoma are rarely reported. Here, we report such a case— the 12th case of synchronous double primary cancers featuring HCC and GC, but the first case of neuroendocrine differentiation in the gallbladder. Case presentation A 77-year-old female was admitted to the hospital complaining of weakness and inappetence for six months. Contrast-enhanced computed tomography (CT) of the abdomen indicated an 11 cm space-occupying lesion in the right lobe of the liver. Later, magnetic resonance imaging showed a high possibility of a massive hepatoma, and multiple gallstones were also seen. After transhepatic arterial chemoembolization, a repeat abdominal CT showed obvious local nodular thickening in the gallbladder wall. Finally, resection of the right lobe of the liver and cholecystectomy were performed. During an approximately 2-year follow-up, the patient recovered uneventfully without recurrence or metastasis. Conclusion The disease in this case is rare and lacked typical radiological features. More precise and advanced diagnostic techniques are needed to obtain a clear diagnosis and refine treatment strategies. The management strategy should always be curative, even in the presence of multiple malignancies.