Reactive angioendotheliomatosis secondary to dermal amyloid angiopathy.

Reactive angioendotheliomatosis (RAE) is a rare benign cutaneous vascular proliferation characterized by intravascular hyperplasia of endothelial cells and tuft-like proliferation of vessels. A 75-year-old man had erythematous and violaceous macules, some stellate and others arranged in a livedoid pattern, evolving toward necrosis with central areas having an "atrophie blanche" appearance spread on the trunk, inguinal folds, and right thigh. He was on hemodialysis and had a benign monoclonal gammopathy. Cutaneous biopsy revealed RAE characterized by the proliferation of epithelioid and spindle-shaped cells in superficial and middermis lining vascular channels, arranged in clusters, and sometimes displaying an intravascular growth pattern. These cells stained for CD31, CD34, and actin. Interestingly, prominent amyloid deposits were found in the wall of some vessels in deep dermis, often causing obstruction of their lumina. The cause of RAE is unknown, but it can be associated with infections, antiphospholipid syndrome, dysglobulinemia, cryoproteinemia, and lower extremities arteritis, and it may occur near arteriovenous fistulas. In this patient, we believe that RAE was caused by obliteration of dermal vessels by amyloid deposits. Indeed, it is thought that RAE could be caused by ischemia secondary to vascular obstruction. This is the first reported patient with RAE associated with amyloid deposits.