The pigmented purpuric dermatoses are a group of chronic diseases of mostly unknown etiology that have a very distinctive clinical appearance. They are characterized by extravasation of erythrocytes in the skin with marked hemosiderin deposition.
A number of clinical patterns of pigmented purpuric dermatoses or capillaritis are recognized that may represent different presentations of the same disorder; however, this generally does not influence the treatment or the prognosis. They all show a similar histologic appearance. The term pigmented purpuric dermatoses includes Schamberg disease (ie, progressive pigmentary dermatosis), purpura annularis telangiectodes (Majocchi disease),  lichen aureus, itching purpura, eczematidlike purpura of Doucas and Kapetanakis, and the pigmented purpuric lichenoid dermatosis of Gougerot and Blum. Many consider itching purpura and eczematidlike purpura to be variants of Schamberg disease.
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.  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.
Pigmented purpuric dermatoses are common.
During a 10-month period, the author's United Kingdom hospital-based dermatology practice, which serves a population of 300,000 persons, identified only 10 such cases. Five cases were diagnosed as having lichen aureus, and the remainder had more extensive capillaritis.
Persons of any race can be affected by pigmented purpuric dermatoses.
Pigmented purpuric dermatoses usually occur more frequently in men than in women. However, purpura annularis telangiectodes of Majocchi is seen more frequently in women.
Schamberg disease may occur in persons of any age.
Itching purpura and the dermatosis of Gougerot and Blum mainly affect middle-aged men.
Lichen aureus and Majocchi disease are predominantly diseases of children or young adults.
Many lesions persist or extend with time. Most eventually resolve spontaneously. Typically, the condition is asymptomatic, but pruritus may sometimes be a prominent feature in some cases, especially in patients with itching purpura or eczematidlike purpura of Doucas and Kapetanakis. These diseases have no systemic findings.
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