The etiology is unknown. Several cofactors have been reported that appear to influence disease presentation, including hypertension, diabetes mellitus, venous stasis, strenuous exercise, gravitational dependency, capillary fragility, focal infections, and chemical ingestion. [2] Histologically, a perivascular T-cell lymphocytic infiltrate is centered on the superficial small blood vessels of the skin, which show signs of endothelial cell swelling and narrowing of the lumen. Extravasation of red blood cells with marked hemosiderin deposition in macrophages is also found, and a rare granulomatous variant of chronic pigmented dermatosis has been reported. [3]
Early onset disease may sometimes be associated with platelet-storage defects. [4]
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Pigmented purpuric dermatitis affecting the trunk. Some of the lesions show the characteristic orange-brown, speckled, cayenne pepper–like discoloration that is the hallmark clinical sign of a capillaritis. Men are more frequently affected than women. If the lesions are pruritic, then the term itching purpura is sometimes used. Early cutaneous T-cell lymphoma, purpuric clothing contact dermatitis, and drug hypersensitivity reactions should be considered in the differential diagnosis.
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Lichen aureus is the name given to localized pigmented purpuric dermatitis or capillaritis. In this patient, the skin on the extensor surface of the elbow is affected.
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Histologic features of a skin biopsy sample obtained from a patient with lichen aureus shows extravasation of erythrocytes and a perivascular T-cell infiltrate.
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Endothelial cell swelling is a histologic feature of capillaritis. This biopsy sample was obtained from a patient with lichen aureus.
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Hemosiderin deposition is seen in dermal macrophages in this biopsy sample obtained from a patient with lichen aureus.
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Capillaritis affecting the lower legs is known as Schamberg disease. In Schamberg disease, irregular plaques and patches of orange-brown pigmentation develop on the lower limbs.
