Epithelioid angiosarcoma: a neoplasm with potential diagnostic challenges.

Epithelioid angiosarcomas are extremely rare tumors associated with poor prognosis and early metastases. Its epithelioid cytomorphology and limited vasoformation make it difficult to distinguish from more common malignancies, such as, carcinoma. This can be a potential diagnostic pitfall for the cytopathologist. In this report, the patient is a 24-year-old man presenting with testicular pain, a pelvic mass, and innumerable liver nodules. Immediate interpretation of the needle core biopsies of the pelvic mass and liver lesions initially favored a poorly differentiated adenocarcinoma. Unusual positive immunohistochemical stains for CD30 and CK7 ultimately led the investigation toward a tumor of mesenchymal origin. Further, immunohistochemical evaluation demonstrated positive CD31 and Factor VIII staining and established the final diagnosis of epithelioid angiosarcoma. The tumor cells were negative for CD34, CK20, alpha-fetoprotein, placental-like alkaline phosphatase, hepatocyte paraffin 1, polyclonal carcinoembryonic antigen, CD10, CA-125, prostate-specific antigen, and prostatic acid phosphatase. This case is reported to illustrate the importance of considering the diagnosis of epithelioid angiosarcoma when encountering an "epithelioid" neoplasm particularly with unusual immunoreactivity for CK7 and CD30.