Reactive angioendotheliomatosis: a study of 15 cases demonstrating a wide clinicopathologic spectrum.

Reactive angioendotheliomatosis (RAE) is a rare condition characterized by cutaneous vascular proliferation that usually occurs in patients with diverse types of coexistent systemic disease. Although intravascular proliferation of endothelial cells has been considered to be the key histologic feature in RAE, other patterns of vascular proliferation have also been described. We reviewed the clinicopathologic features in 15 cases of RAE. The study group comprised eight males and seven females with an age range of 47-88 years (median 65 years). Eleven patients had coexistent systemic disease: renal disease (six patients, including three post renal transplantation); valvular cardiac disease (two patients); one patient each had alcoholic cirrhosis, glioblastoma multiforme (on chemotherapy), and rheumatoid arthritis/polymyalgia rheumatica. Six patients were iatrogenically immunosuppressed at the onset of the skin lesions. The clinical appearance included multiple erythematous macules, plaques, tumors, and ulcerated lesions, with a wide distribution but a propensity to involve limbs. Lesions had been present for 1 month to 4 years (median 4 months). Lesions resolved in four cases, improved in two cases, remained static in one case, and progressed in four cases. Two cases were recent and follow-up was not available in two other cases. Three patients died of their coexistent systemic disease with resolution, improvement, and progression of lesions, respectively. All lesions were characterized histologically by a proliferation of capillaries in the dermis, with variably diffuse (seven cases), lobular (six cases), or mixed lobular and diffuse patterns (two cases). There was marked intercase and intracase heterogeneity in histologic features. Common features included fibrin microthrombi (nine cases), reactive (fasciitis-like) dermal alterations (seven cases), and foci of epithelioid endothelium (four cases). Four of 10 cases tested showed positive immunohistochemical staining for HHV-8 latent nuclear antigen in lesional endothelial cell nuclei. This study suggests that RAE has a broader clinicopathologic spectrum than previously described. The pathogenesis of this rare disorder is unknown, but it is likely that immunologic factors play a role.