Massive hemorrhagic functional adrenal adenoma histologically mimicking angiosarcoma. Report of a case with immunohistochemical study.

We report the case of a massive hemorrhagic/thrombosed functional adrenal adenoma, a very uncommon mass lesion of the adrenal gland. The lesion contained large areas that histologically mimicked the pattern of an angiosarcoma. Immunoperoxidase staining confirmed that the vascular lining cells were positive for vimentin and negative for three vascular markers (factor VIII antigen, Ulex europaeus agglutinin I, thrombomodulin), cytokeratin, keratin, epithelial membrane antigen, and S100 antigen. Endothelial immunohistochemical markers can be useful as a diagnostic adjunct in differentiating this type of reactive hemorrhagic/thrombotic lesion from angiosarcoma.