Pathology of Reactive Angioendotheliomatosis
angioendotheliomatosis is a rare cutaneous vascular proliferation
characterized by intravascular hyperplasia of endothelial cells and
tuft-like proliferation of vessels.
Many cases are associated with severe systemic disease or immunosuppression.
Example- Post renal transplantation, valvular cardiac disease, alcoholic cirrhosis, rheumatoid arthritis, severe peripheral vascular atherosclerotic disease, and iatrogenic arteriovenous fistulas.
Reactive angioendotheliomatosis may be associated with lesions which display luminal obstruction by thrombi or abnormal proteins ( chronic disseminated intravascular coagulation, cryoglobulinemia, intravascular immunoglobulin deposits associated with a monoclonal gammopathy, infections, paraproteinemia with myelomatosis ).
Malignant angioendotheliomatosis is not related to the reactive variant.
This is a systemic angiotropic lymphoma mostly of the B-cell phenotype.
Age: Reactive angioendotheliomatosis has no age predilection.
Clinical Presentation: Presents as erythematous macules, papules and plaques.
Necrosis and ulceration may sometimes develop.
The lesions measure from 1 to 3 cm or more in diameter.
Site: The lesion may occur at any body site.
The lesion is characterized by the proliferation of epithelioid and spindle-shaped cells in superficial and mid-dermis lining vascular channels, arranged in clusters, and sometimes displaying an intravascular growth pattern.
The cells often occlude the vascular lumina. There is no cytologic atypia.
There may be focal extravasation of red blood cells.
In some cases fibrin thrombi may be identified.
Other features include focal glomeruloid features and deposition of periodic acid-Schiff-positive material.
Variant: Diffuse dermal angiomatosis:
Characterized by hyperplastic endothelial cells interstitially arranged between collagen bundles of the reticular dermis.
The cells form small lumina. In reactive angioendotheliomatosis there is intravascular proliferation.
The intravascular cells are positive for Factor VIII-related antigen, CD31, CD34.
The proliferating pericytic myoepithelial cells are actin positive.
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