High-grade angiosarcoma presenting with cytology-negative hemorrhagic ascites.

Angiosarcomas are a rare subtype of soft-tissue sarcomas originating from the vascular endothelium. Both retroperitoneal and omental angiosarcomas tend to be aggressive and rapidly fatal if not amenable to early intervention. In this report, we describe an unusual case of high-grade angiosarcoma with cytology-negative hemorrhagic ascites and diffuse omental invasion. Multiple investigations into the origin of the hemorrhagic ascites, including cytological analysis, tumor marker measurements, serum-ascites albumin gradient calculation and frozen section pathological examination, failed to reveal a diagnosis. We conclude that malignancy should be considered in the differential diagnosis in the presence of suspicious cytology-negative hemorrhagic ascites and concomitant retroperitoneal and abdominal findings.