Intravascular and diffuse dermal reactive angioendotheliomatosis secondary to iatrogenic arteriovenous fistulas.

Reactive angioendotheliomatosis is a rare benign process that has been mainly described in patients with systemic infections, such as subacute bacterial endocarditis or tuberculosis, and in association with intravascular deposition of cryoproteins. Histopathologically, it is characterized by a proliferation of endothelial cells within vascular lumina resulting in the obliteration of the involved vessels. Another rare variant of reactive angioendotheliomatosis has been described in the lower extremities of patients with severe peripheral vascular atherosclerotic disease. It consists of violaceous and purpuric plaques histopathologically characterized by diffuse proliferation of endothelial cells interstitially arranged between collagen bundles of the reticular dermis. This second variant has been named diffuse dermal reactive angioendotheliomatosis. We report two patients with reactive cutaneous angioendotheliomatosis appearing distally to arteriovenous fistulas used for hemodialysis because of chronic renal failure. The first patient showed intravascular reactive angioendotheliomatosis, while the second one had purpuric plaques that were characterized histopathologically by diffuse dermal angioendotheliomatosis. Both patients showed an arteriovenous "steal" syndrome with distal ischemia, and it is possible that a local increase of vascular endothelial growth factor, as is the case in hypoxia situations, induces the endothelial proliferation. To the best of our knowledge, cutaneous reactive angioendotheliomatosis has not been previously described in association with arteriovenous shunts.