CASE #2: Benign pigmented purpura
Also known as pigmented purpuric dermatoses, benign pigmented purpura (BPP) include a spectrum of disorders characterized clinically by a purpura that morphologically appears to have distinct forms but histologically appears indistinguishable. BPP can be seen in the following conditions: Schamberg’s disease, Majocchi’s disease,4 lichen aureus, pigmented purpuric lichenoid dermatosis of Gougerot and Blum, eczematid-like purpura of Doucas and Kapetanakis, and itching purpura of Loewenthal. These dermatoses can manifest with petechiae and/or purpura and are usually found on the lower legs, but any area of the body can be affected. BPP is not associated with serious sequelae. However, the condition can persist for years and may be associated with such troubling symptoms as itching and patient distress over the cosmetic appearance.5
The lesions in Schamberg’s disease have been likened in appearance to cayenne pepper because of the pinhead-sized reddish puncta. Another name for Schamberg’s disease is progressive pigmented dermatosis, as these puncta can form irregular plaques of orange or brown pigmentation. Majocchi’s disease is most common in young women. Lesions in Majocchi disease are punctate telangiectatic macules progressing to annular, hyperpigmented patches; thus, Majocchi’s disease is also known as purpura annularis telangiectodes. The term lichen aureus describes the lichenoid macules and papules and golden-bronze color of the typical eruption. Lesions in pigmented purpuric lichenoid dermatosis of Gougerot and Blum are minute, lichenoid papules that tend to fuse into plaques of various hues. Eczematid-like purpura of Doucas and Kapetanakis is characterized by purpura with scale on the surface. In itching purpura of Loewenthal, the lesions are more extensive, and patients typically complain of severe pruritus.
The etiologies of these conditions of the pigmented purpuric dermatoses are unknown, but a common pathogenetic mechanism is suspected. These conditions have a similar histological presentation—a perivascular infiltrate composed of T-cell lymphocytes and macrophages centered on the superficial small blood vessels of the skin. Signs of endothelial cell swelling and narrowing of the lumen are typically seen. Extravasation of red blood cells (resulting in purpura) and marked hemosiderin deposition in macrophages are also found.
Dermoscopy has been reported to be a useful tool for assisting in the clinical diagnosis of BPP.6 A complete blood count and peripheral smear should be done to rule out thrombocytopenia. Prothrombin time and partial thromboplastin time may also be done to exclude other possible causes of purpura. Tests for antinuclear antibody; rheumatoid factor; human type B hepatitis, surface antigen antibody; and anti-hepatitis C virus antibody should also be considered.
Extensive pigmented purpura should be biopsied. Skin biopsy helps confirm the diagnosis of BPP and exclude mycosis fungoides, which in its early stages may closely resemble a pigmented purpuric dermatitis. Despite its name, mycosis fungoides is not a fungal infection but rather a cutaneous T-cell lymphoma. The skin lesions in mycosis fungoides result from a proliferation in the dermis of malignant T lymphocytes, which have a tendency to migrate into the epidermis. Skin biopsy of the lesions demonstrate small-to medium-sized atypical lymphocytes with highly convoluted or cerebriform nuclei infiltrating the upper dermis. Skin biopsy may also demonstrate Pautrier microabscesses (collections of atypical lymphocytes), which are pathognomonic for mycosis fungoides. The prognosis of mycosis fungoides varies with disease stage. In most patients, mycosis fungoides is a chronic disease with a slow progression over many years.
BPP may resolve spontaneously, and no medical intervention has been proven to treat BPP. Compression stockings may help by decreasing venous stasis and edema. Topical steroids are recommended to help control BPP and may also offer relief from pruritus. Psoralen photochemotherapy has had beneficial results in several case reports. Such systemic therapies as methotrexate should be reserved for patients with highly symptomatic disease refractory to other treatments.
The patient in this case was treated with triamcinolone ointment 0.1% with partial improvement over two months. n
Ms. Callenback is a medical student at the University of California, Irvine School of Medicine. Dr. Scheinfeld is assistant clinical professor of dermatology at Columbia University in New York City, where he has a private practice. Neither has any relationship to disclose relating to the content of this article.
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