Hemorrhagic Epithelioid Angiosarcoma of the Peritoneal Cavity Clinically Posing as a Dissecting Abdominal Aortic Aneurysm; A Case Report and Literature Review

Abstract

Epithelioid angiosarcoma (EA) is a very rare, malignant, vascular neoplasm that is difficult to diagnose and treat. To our knowledge involvement of the omentum and, or mesentery has been reported in only four other cases. Angiosarcomas comprise less than 2% of all sarcomas, and sarcomas comprise less than 1% of soft tissue cancers. Among angiosarcomas, the epithelioid variant is exceedingly rare. The differential diagnosis for abdominal pain is extensive and includes abdominal aortic aneurysm (AAA), mesenteric ischemia and infarction, peritonitis, and intestinal obstruction. Based on laboratory and imaging studies, inclusion of mesenteric angiosarcoma may be warranted in this list of differentials . Since these neoplasms are readily mistaken for carcinomas and melanomas, immunohistochemical staining is vital to diagnosing these lesions. The patient’s omentum and mesenteric lesions were positive with epithelial marker AE-1/AE-3; the vascular markers CD31, Factor VIII, and CD34; as well as endothelial marker Fli-1 supporting the diagnosis of epithelioid angiosarcoma. Interestingly, the human herpes virus stain was negative. This case demonstrates the importance of considering epithelioid angiosarcoma in the differential diagnosis of patients presenting with progressively worsening abdominal pain and findings reminiscent of a rupured aortic aneurysm. Also challenging is the histopathologic diagnosis of these tumors due to the ‘‘epithelioid’’ features of the neoplastic endothelial cells. Utilizing appropriate immunohistochemical studies can be extremely helpful in this regard.