Case Report: A rare case of gallbladder carcinosarcoma with osteosarcomatous differentiation.

Gallbladder carcinosarcoma (GBCS) is indeed an exceptionally rare and aggressive malignancy, accounting for less than 1% of all primary gallbladder tumors. This tumor is characterized by the presence of both carcinomatous (epithelial) and sarcomatous (mesenchymal) components, making it a unique and diagnostically challenging entity. Herein, we report a case of a 71-year-old female patient who presented with a one-year history of vague epigastric pain. AFP levels were markedly elevated. Preoperative imaging revealed gallbladder enlargement with heterogeneous contrast enhancement, raising suspicion of malignancy. The patient subsequently underwent radical cholecystectomy, and postoperative histopathological examination confirmed the diagnosis of GBCS with osteosarcomatous differentiation. The patient has since completed her first cycle of chemotherapy. Even with radical resection and adjuvant chemotherapy, GBCS carries a grave prognosis. Heightened clinical suspicion, thorough imaging assessment, and confirmatory histopathological biopsy are essential for accurate preoperative diagnosis. Surgical optimization and personalized treatment strategies remain critical to improving outcomes.