An uncommon cause of ascites: spontaneous rupture of biliary cystadenoma

Biliary cystadenomas are cystic hepatic tumours of biliary origin. Cystadenomas are often slow-growing benign tumours, but always harbour the risk of malignant transformation. Cystadenomas are often asymptomatic, but may present with abdominal pain and distension. Though suspected with cross-sectional abdominal imaging, definitive diagnosis almost always requires histology. Spontaneous rupture of cystadenoma had been reported three times in the medical literature to date, all presenting with peritonitis. Here we report a case of spontaneous intraperitoneal rupture of biliary cystadenoma presenting as ascites without peritonitis.