Background
Pigmented purpuric dermatoses are a group of chronic cutaneous diseases of mostly unknown etiology, characterized by multiple petechial hemorrhage due to capillaritis. The presentation includes red-to-purple macules that evolve to a golden-brown color with reabsorbtion of the hemosiderin. Lesions usually occur bilaterally on the lower limbs but may also involve the thighs, buttocks, trunk, and arms. Lesions are frequently asymptomatic, though they may be mildly pruritic. [1]
A number of clinical patterns of pigmented purpuric dermatoses or capillaritis are recognized that may represent different presentations of the same disorder; however, these differences in presentation generally do not influence the treatment or the prognosis. They all show a similar histologic appearance. On the basis of clinical appearance, pigmented purpuric dermatoses are classified as follows [1] :
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Progressive pigmentary dermatosis or Schamberg disease
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Pigmented purpuric lichenoid dermatosis of Gougerot and Blum
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Purpura annularis telangiectodes of Majocchi
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Eczematidlike purpura of Doucas and Kapetanakis
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Lichen aureus
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Unilateral linear pigmented purpura
Schamberg disease is the most common subtype with a symptomatic variant, itching purpura of Loewenthal, characterized by abrupt onset and severe itching. Eczematidlike purpura is also considered to be a symptomatic variant of Schamberg disease. [1]
Granulomatous pigmented purpuric dermatosis (GPPD) is a rare subtype. It is distinguished from other subtypes by an inflammatory infiltrate that can extend to the middle or deep dermis, and the admixed lymphocytic infiltrate is mainly composed of CD8+ T cells. [2]
Pathophysiology
The cause 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. [3] Alcohol use may be related to the development of Schamberg disease, especially in cases resulting in liver disease. [1]
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. [4]
Early-onset disease may sometimes be associated with defects in platelet storage. [5]
Etiology
The etiology 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
US and international statistics
Pigmented purpuric dermatoses are common in the United States.
In one hospital-based dermatology practice in the United Kingdom, which served a population of 300,000 persons, only 10 cases of pigmented purpuric dermatosis were identified over a 10-month period. Five patients were diagnosed as having lichen aureus, and the remainder had more extensive capillaritis.
Age-, sex-, and race-related demographics
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.
Pigmented purpuric dermatoses usually occur more frequently in men than in women. However, purpura annularis telangiectodes of Majocchi is seen more frequently in women.
Persons of any race can be affected by pigmented purpuric dermatoses.
Prognosis
Many lesions persist or extend with time; however, most eventually resolve spontaneously. Typically, the condition is asymptomatic, but pruritus may 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 trunk. Some lesions show characteristic orange-brown, speckled, cayenne pepper–like discoloration (hallmark clinical sign of capillaritis). Men are more frequently affected than women. Pruritic lesions are sometimes referred to as itching purpura. Early cutaneous T cell lymphoma, purpuric clothing contact dermatitis, and drug hypersensitivity reactions should be considered in differential diagnosis.
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Localized pigmented purpuric dermatitis or capillaritis is referred to as lichen aureus. In this patient, skin on extensor surface of elbow is affected.
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Histologic features of skin biopsy sample obtained from patient with lichen aureus include extravasation of erythrocytes and perivascular T cell infiltrate.
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Endothelial cell swelling is histologic feature of capillaritis. Biopsy sample was obtained from patient with lichen aureus.
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Hemosiderin deposition is seen in dermal macrophages in biopsy sample obtained from patient with lichen aureus.
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Capillaritis affecting lower legs is referred to as Schamberg disease. In Schamberg disease, irregular plaques and patches of orange-brown pigmentation develop on lower limbs.
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