A Resected Case of Metachronous Gallbladder Metastasis of Gastric Cancer Mimicking Gallbladder Cancer.

[INTRODUCTION] Gallbladder metastases from malignancies, including gastric cancer, are extremely rare. Diagnosis is challenging due to the lack of specific symptoms and the absence of distinctive radiological features that can differentiate metastatic lesions from primary gallbladder tumors.

[CASE PRESENTATION] An 81-year-old male was diagnosed as early gastric cancer and underwent endoscopic submucosal dissection and additional laparoscopic proximal gastrectomy for residual tumor and lymph node metastasis 5 years prior. Following adjuvant chemotherapy, the patient underwent multiple interventions for metastatic disease, including liver resection for liver metastasis of segment 2/3, radiofrequency ablation for liver metastasis of segment 5/6, and lobectomy of the right middle lobe for lung metastasis. During follow-up, a nodular lesion was newly detected at the gallbladder fundus through computed tomography. Diagnostic imaging, including endoscopic ultrasonography and Gd-EOB-DTPA, suggested a potential gallbladder cancer with sub-serosal lesion. We performed an extended cholecystectomy lymph node dissection, and pathological examination revealed the tumor to be a gallbladder metastasis from the original gastric cancer, confirmed through immunohistochemical staining.

[CONCLUSIONS] We herein report a rare case of metachronous gallbladder metastasis from gastric cancer. Preoperative diagnosis of gallbladder metastasis is challenging due to its radiological similarity to primary gallbladder cancer.