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Skin-nontumor / Clinical Dermatology

Other dermatoses

Segmented hyalinizing vasculitis


Reviewer: Mowafak Hamodat, MB.CH.B, MSc., FRCPC, Eastern Health, St. Johns, Canada (see Reviewers page)
Revised: 2 August 2011, last major update August 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.

Definition
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● Manifestation of a thrombogenic vasculopathy in which occlusion of small dermal vessels by fibrin thrombi is the primary event

Terminology
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● Also called atrophie blanche of Milian

Clinical features
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● Affects lower legs, particularly ankles and dorsum of feet, rarely the extensor arm surfaces below the elbows
● Elevated levels of fibrinopeptide A are suggestive of a thrombogenic state
● Several cases with lupus-type anticoagulant and increased level of anticardiolipin antibodies have been reported
● Other associations include protein C deficiency, factor V Leiden mutation, prothrombin mutation, plasminogen activator inhibitor-1 promoter mutation (OMIM 173360), antithrombin III deficiency, methylenetetrahydrofolate reductase mutation (OMIM 607093), homocysteinemia and essential cryoglobulinemia, all of which contribute to a hypercoagulable condition

Treatment
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● Antiplatelet drugs and antithrombotic drugs may be useful
● Also dapsone, nicotinic acid, intravenous immunoglobulin, PUVA therapy, danazol and hyperbaric oxygen therapy
● Warfarin therapy is sometimes used to treat the associated/concurrent abnormalities in one or more clotting factors
● Also cessation of smoking, low-dose aspirin, oral pentoxifylline and oral dipyrimadole
● Folic acid is recommended for those with an MTHFR mutation, hydrochloroquine for patients with antiphospholipid antibodies and anabolic steroids (stanozolol or danazol) for patients with cryofibrinogenemia

Clinical description
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● Painful purpuric ulcers with reticular patterning on the lower extremities

Clinical images
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Various images

Micro description
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● Dermal capillaries have focal endothelial proliferation and wall thickening by PAS+ material, with fibrin thrombi causing occlusion
● Specific changes vary by age of lesion
● Primary event is formation of hyaline thrombi in lumen of small vessels in upper and mid dermis; rarely deeper vessels are involved; PAS+ diastase resistant fibrinoid material also present in walls of blood vessels and in perivascular stroma; also infarction of superficial dermis, often with a small area of ulceration
● Sometimes a thin parakeratotic layer is present overlying infarcted or atrophic epidermis
● Epidermis adjacent to ulceration may be spongiotic; a sparse perivascular lymphocytic infiltrate may be present, but there is no vasculitis
● Neutrophils, if present, are usually sparse and confined to infarcted upper dermis and ulcer base
● Often extravasated red cells in upper dermis
● Small blood vessels often increased in adjacent papillary dermis, but this is a common feature in biopsies from lower legs
● In older lesions, there is thickening and hyalinization of dermal vessels with some endothelial edema and proliferation
● Fibrinoid material may also be present in vessel walls
● In even older lesions, there is dermal sclerosis and scarring with some dilated lymphatics and epidermal atrophy; there may be a small amount of hemosiderin in upper dermis
● As old lesions may become involved again, it is possible to find dermal sclerosis in some early lesions

Positive stains
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● Immunofluorescence will demonstrate fibrin in vessel walls in early lesions; in later stages there are also immunoglobulins and complement components in broad bands about vessel walls

End of Skin-nontumor / Clinical Dermatology > Other dermatoses > Segmented hyalinizing vasculitis


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