Acute Malignant Ascites Revealing Mucinous Adenocarcinoma of the Gallbladder: A Rare Case in a Recent Migrant.

Mucinous adenocarcinoma of the gallbladder is a rare and aggressive histologic subtype, most often diagnosed at an advanced stage due to its nonspecific clinical presentation. We report the case of a 50-year-old male who recently migrated from Venezuela and presented with progressive abdominal distension, peripheral edema, and systemic symptoms. Diagnostic paracentesis revealed a low serum-ascites albumin gradient (SAAG), raising concern for malignancy. Cross-sectional imaging demonstrated a large gallbladder mass with hepatic metastases, and histopathologic analysis from liver biopsy confirmed stage IV mucinous adenocarcinoma. Despite initially preserved functional status, the patient experienced rapid clinical deterioration, developing duodenal obstruction, sepsis, and multi-organ failure, leading to death within 48 hours of readmission. This case highlights the aggressive clinical course and diagnostic challenges of mucinous gallbladder carcinoma. It underscores the importance of early tissue diagnosis in patients with low-SAAG ascites, even when initial cytology is inconclusive, and reinforces the need for heightened clinical suspicion for underlying malignancy in patients presenting with unexplained ascites.