A 54-year-old man with a history of Klippel-Trenaunay syndrome (KTS) presented with unilateral left lower extremity painless skin lesions that had been increasing in size for the past several years (Figure 61-1). He first noticed several purplish raised areas that transformed into nodules that slowly and progressively increased in size. Biopsy revealed a regular pattern of small blood vessel proliferation, fibroblasts, extravasated erythrocytes, and hemosiderin deposition within the dermis. No endothelial cell atypical mitoses or vascular slits were identified. Polymerase chain reaction (PCR) analysis for human herpesvirus 8 (HHV 8) was negative. A diagnosis of acroangiodermatitis or pseudo-Kaposi sarcoma was made.
Acroangiodermatitis (pseudo-Kaposi sarcoma) presenting as dark purplish verrucous nodules on the dorsum of the distal foot and toes with proximal papules and plaques. (Photograph courtesy of Steven M. Dean, DO).
Acroangiodermatitis of Mali, which is also referred to as simply acroangiodermatitis or pseudo-Kaposi sarcoma, is a rare vascular phenomenon with skin manifestations characterized by violaceous nodules or plaques arising from hyperplasia of pre-existing vasculature due to severe chronic venous insufficiency (CVI) and associated venous hypertension. The term pseudo-Kaposi sarcoma originated from clinical similarities and histologic characteristics of the cancerous condition Kaposi sarcoma.1 The term acroangiodermatitis was first described by Mali and Kuiper in 1965, who described 18 patients with mauve-colored macules, papules, and/or nodules predominantly over the extensor surface of feet with underlying chronic venous insufficiency.2 In 1967, morphologically similar lesions were described independently by Stewart as well as by Bluefarb and Adams on the legs of patients with arteriovenous malformations (AVMs) and coined Stewart-Bluefarb syndrome.3
ETIOLOGY AND PATHOGENESIS
Acroangiodermatitis is reported in patients with CVI,2 paralyzed extremities,4 amputation stumps (especially with poor-fitting suction-type prostheses),5 iatrogenic arteriovenous fistula (AVF),6 and in association with KTS,7 homozygous activated protein C resistance,8 and 20210A prothrombin gene mutation carriers.9
Acroangiodermatitis associated with CVI is hypothesized to be a direct effect of severe venous valvular incompetence with or without insufficiency of the calf muscle pump. Sustained venous hypertension leads to elevation of the capillary pressure and chronic tissue hypoxia that triggers neovascularization and fibroblast proliferation.10
Stewart-Bluefarb syndrome is clinically and histologically similar to pseudo-Kaposi sarcoma and is associated with AVMs. The inciting event may be different from pseudo-Kaposi sarcoma and triggered by stimulation of endothelial growth from the resultant increase in venous pressure from associated AVMs.11 Reports postulate that the inciting mechanism is related to an increase in endothelial growth factor signaling proteins from local ischemia induced by the AVMs.12