An obstructed venous aneurysm presenting as an abdominal mass: report of a case.

We report herein the case of a 32-year-old woman found to have a venous aneurysm originating from the ovarian vein. The patient presented with a 9-cm abdominal tumor, and surgery was performed under the preoperative diagnosis of a mesenteric cyst. The tumor was easily ablated from the mesentery and resected with the right ovarian artery and vein. Histologically, the wall of the cyst showed the structure of a vein, and the diagnosis of a venous aneurysm was made. This disease is difficult to diagnose preoperatively when a patient presents with no symptoms other than a palpable mass, or when the lumen is obstructed by thrombus. This report serves to demonstrate that a venous aneurysm should be considered in the differential diagnosis of an asymptomatic abdominal mass.