Bilious pleural effusion following cholecystostomy in an immunocompromised elderly male

A biliopleural fistula (BPF) is a rare, potentially life-threatening complication of hepatobiliary interventions, often presenting as bilious pleural effusion. Prompt diagnosis is essential, particularly in immunocompromised patients. We report a 74-year-old male with thrombotic thrombocytopenic purpura (TTP) who developed acute acalculous cholecystitis during treatment with plasmapheresis and rituximab. Due to severe thrombocytopenia, a percutaneous cholecystostomy was performed. Two days later, he developed a right-sided pleural effusion with recurrent fever. Thoracentesis yielded bilious fluid, and imaging revealed a hepatic abscess with a fistulous tract. The patient was treated with chest tube drainage, broad-spectrum antibiotics and endoscopic retrograde cholangiopancreatography (ERCP) for biliary decompression. This multidisciplinary approach led to closure of the fistula and full clinical recovery. This case highlights the importance of considering BPF in patients with new pleural effusion following hepatobiliary procedures. Early pleural fluid bilirubin analysis, targeted imaging and coordinated management with drainage and ERCP are crucial for favourable outcomes in high-risk patients.