An incidentaloma not to be missed

A frail 92-year-old woman presented with pelvic and femoral fragility fractures after a fall. She had synchronous gross abdominal distension which was diagnosed as ascites. Computed tomography was requested to exclude malignancy before performing paracentesis.

Formal imaging showed a large intraperitoneal structure. The 4-Hounsfield unit attenuation was consistent with simple fluid. However, identification of septations, together with rim enhancement, led to a revised diagnosis of a cystic mass. The lesion measured 24 cm × 28 cm × 33 cm and, at an estimated volume of 16 L, displaced most of the abdominal and pelvic viscera. Fortunately, this was recognised before paracentesis.