Pathology of Acroangiodermatitis (Pseudo-Kaposi's Sarcoma)

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Pathology of Acroangiodermatitis /Pseudo-Kaposi's Sarcoma

2023

(Acroangiodermatitis of Mali / Stewart-Bluefarb syndrome )

Acroangiodermatitis is a benign vascular process which histologically closely resembles Kaposi's Sarcoma and had thus been named "pseudo-Kaposi's sarcoma".

Acroangiodermatitis is often associated with different disorders like: chronic venous insufficiency, arterio-venous malformations, arterio-venous shunts, acquired arteriovenous fistula, paralysed limb, Klippel-Trenaunay-Weber syndrome.

It has also been reported above knee amputation stump.

Site: Lower part of the legs and on the feet.

Clinical presentation: The lesion presents as circumscribed violaceous, brown or dusky macules, papules, plaques and nodules.

Microscopic features:

Proliferation of small dilated vessels in a thickened edematous papillary dermis and sometimes in the upper reticular dermis.

The vessels have a regular profile. Some lesions show nodular collection of blood vessels with perivascular inflammation.

The small vessels are thick walled and are lined by plump endothelial cells. There are no atypical features.

There is some perivascular fibroblastic proliferation with variable fibroplasia.

Other features : Hyperkeratosis of overlying epidermis ; extravasated red blood cells , hemosiderin and variable infiltrate of lymphocytes around vascular proliferation.

Differential diagnosis:

Kaposi's Sarcoma - Thin-walled vessels aligned along normal venules ; jagged outline ; thin oval endothelial cells distributed interstitially in the reticular dermis; an infiltrate of plasma cells around pre-existing venules ;

In contrast to true Kaposi's Sarcoma , in acroangiodermatitis human-herpes-virus-8 DNA can not be detected by polymerase-chain-reaction;

Kaposi's Sarcoma showed CD34 positive staining of endothelial cells and on the characteristic spindle-shaped, perivascular cells.

Biopsies of pseudo-Kaposi's sarcoma showed a strong CD34 positive staining of endothelial cells of hyperplastic vessels.

However, in sharp contrast with Kaposi's sarcoma, a complete absence of perivascular CD34 expression was noted.

Stasis dermatitis - (unlike stasis dermatitis, acroangiodermatitis is usually associated with minimal epidermal changes and eosinophils in the inflammatory infiltrate in the dermis ) ;

Pigmented purpura ; vasculitis.