Observations concerning the pathogenesis of epithelioid hemangioma (angiolymphoid hyperplasia).

Epithelioid hemangioma (EH) is a benign vascular lesion that is characterized by well-formed, capillary-sized vessels lined by histiocytoid or epithelioid endothelial cells and often accompanied by a secondary inflammatory infiltrate. Whether or not these lesions are reactive or neoplastic has been debated and is reflected in the various designations, such as angiolymphoid hyperplasia with eosinophilia (ALHE), pseudopyogenic granuloma, and inflammatory angiomatous nodules. In order to study the pathogenesis of this lesion, 96 examples of EH of superficial and deep soft tissue origin were reviewed, noting the frequency with which these lesions arose adjacent to a damaged vessel and the incidence of antecedent trauma. In 60 cases (63%), an artery or vein was associated with the mass and, in the majority (52 cases), the vessel was damaged, as evidenced by the presence of fibrointimal proliferation, discontinuity of the internal elastic lamina, and/or mural disruption. No evidence of active arteritis was seen in any case. Antecedent trauma was documented in 12 cases and, in one of these, the subsequent formation of an arteriovenous malformation and development of the EH were noted. EH associated with damaged vessels or those in which a preceding history of trauma was available did not differ histologically from cases in which these variables were absent. Our findings suggest that a significant percentage of EH of soft tissue are not neoplastic, but arise on a reactive basis probably secondary to damage and repair of an artery or vein.