Background
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), [1] lichen aureus, itching purpura, eczematidlike purpura of Doucas and Kapetanakis, and the pigmented purpuric lichenoid dermatosis of Gougerot and Blum. [2, 3] Many consider itching purpura and eczematidlike purpura to be variants of Schamberg disease.
Pathophysiology
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. [4] 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. [5]
Early onset disease may sometimes be associated with platelet-storage defects. [6]
Etiology
The cause of pigmented purpuric dermatoses is unknown. Rare familial cases of Schamberg disease and Majocchi disease have been reported in the literature, implying a genetic cause in a minority of patients.
Epidemiology
Frequency
United States
Pigmented purpuric dermatoses are common.
International
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.
Race
Persons of any race can be affected by pigmented purpuric dermatoses.
Sex
Pigmented purpuric dermatoses usually occur more frequently in men than in women. However, purpura annularis telangiectodes of Majocchi is seen more frequently in women.
Age
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.
Prognosis
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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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.
