Gallbladder Adenocarcinoma With Metastasis in a Young Patient Without Traditional Risk Factors.

Gallbladder cancer (GBC) is an aggressive malignancy with a poor prognosis, often diagnosed incidentally or at an advanced stage. We describe a case of gallbladder carcinoma in a 30-year-old female presenting with a two-week history of upper abdominal pain radiating to the back, bloating, and excessive gas. Laboratory evaluation showed markedly elevated carcinoembryonic antigen levels, and MRI demonstrated a polypoidal gallbladder fundal mass without evidence of gallstones. The patient underwent laparoscopic cholecystectomy, and histopathology confirmed biliary-type adenocarcinoma and evidence of metastasis. Postoperatively, she was diagnosed with stage IV disease and started on systemic therapy with pembrolizumab, gemcitabine, and cisplatin. After three cycles, PET/CT revealed complete metabolic resolution of metastases, with normalization of tumor markers. This case highlights that GBC can occur in young patients and may present at advanced stages even in the absence of gallstones, emphasizing the importance of early suspicion when evaluating gallbladder masses and the potential effectiveness of combined chemo-immunotherapy in achieving meaningful responses.