proliferating angioendotheliomatosis proliferating angioendotheliomatosis proliferating angioendotheliomatosis has historically been divided into two groups, (1) a reactive, involuting type and (2) a malignant, rapidly fatal type.: 598 proliferating angioendotheliomatosisspecialtyoncology the reactive involuting type, reactive angioendotheliomatosis is an rare cutaneous condition characterized histologically by a dense proliferation of small capillaries, and occurs in people with various diseases including subacute bacterial endocarditis and end-stage atherosclerotic disease. these people present with various skin lesions and rashes - most commonly on the thighs. treatment aimed at the underlying condition hastens the resolution of the lesions. the malignant type is an intravascular lymphoma, usually of the diffuse b-cell type, known as intravascular large b-cell lymphoma. it progresses rapidly through involvement of multiple body systems and mortality occurs in less than a year from the initial diagnosis. the average age of diagnosis being 55 years. the causative mechanism is unknown. in a few cases treatment with palliative chemotherapy has been effective.: 598 classification of proliferating angioendotheliomatosis proliferating angioendotheliomatosis may be divided into two types: a reactive type – reactive angioendotheliomatosis a malignant type – intravascular large b-cell lymphoma treatment in few cases palliative chemotherapy is effective. a 30-year-old woman was diagnosed with cutaneous proliferating angioendotheliomatosis. she was treated with a local excision and radiotherapy.