Figure 2. Histopathology showing interstitial and perivascular lymphocytic infiltrate of the superficial dermis, with erythrocyte extravasation and siderophages (H&E, x100)
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| Figures 1A and 1B. Nonblanchable purpuric plaques and patches with annular configuration and central lightening in both lower
limbs Figure 2. Histopathology showing interstitial and perivascular lymphocytic infiltrate of the superficial dermis, with erythrocyte extravasation and siderophages (H&E, x100) |
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An otherwise healthy 16-year-old female patient was observed in our department because of a 4-week history of pruritic, nonblanchable purpuric patches and plaques, symmetrically distributed on both lower limbs. The plaques were 2 to 10 cm in diameter and had an annular configuration with central clearing (Figures 1A and 1B). Additional studies, including blood count with platelet count, basic biochemical profile, erythrocyte sedimentation rate, coagulation studies, and autoimmune screening were normal or negative. A punch biopsy specimen was obtained from a lesion (Figure 2).
Purpura annularis telangiectodes (PAT) is a rare form of pigmented purpuric eruption, first described in 1896 by Majocchi [1]. It occurs most commonly on the lower extremities and buttocks of adolescents and young adults. Clinically, the disease is characterized by symmetrical, nonblanchable, purpuric, telangiectatic and atrophic patches that coalesce to form annular patches and plaques [1, 2, 3, 4, 5]. The etiology of PAT is unknown. It has been associated with the effects of exercise, and venous pressure, hence the tendency for the development of lesions in the lower extremities. Another possible etiopathogenic mechanism is capillary leakage secondary to Langerhans cells-mediated injury and immune-complex deposition [1, 2, 3, 4, 5].
The pigmented purpuric dermatoses (PPD) comprise a group of benign chronic eruptive diseases of unknown etiology, usually characterized by asymptomatic petechial/purpuric pigmented lesions located on the lower limbs. Histologically, they are characterized by a perivascular lymphocytic infiltrate of the upper dermal capillaries and extravasation of erythrocytes with hemosiderin deposits in macrophages [2, 4, 6]. There are a number of entities encompassed under the category of PPD that probably have a common pathogenesis and differ mainly by location and morphology of the lesions. However, these differences generally do not influence management or prognosis [2]. Because there is a marked clinical and histopathological overlap, they are thought to represent a spectrum of one disease. PPD are traditionally divided into 5 clinical entities: a) Majocchi purpura, or purpura annularis telangiectoides; b) Schamberg purpura, or progressive pigmentary dermatosis, characterized as “cayenne-pepper” spots, usually on lower extremities of middle age patients; c) lichen aureus, presenting as a solitary golden-colored patch with purpura, potentially painful and mostly affecting adults; d) Gougerot-Blum purpura, or pigmented purpuric lichenoid dermatitis, characteristically presenting as lichenoid papules with purpura on lower limbs of males aged 50 to 60 years old; e) eczematid-like purpura of Doucas and Kapetanakis, characterized by itching and orange-colored pigmentation, with spongiosis in the histopathology [2].
Despite the distinctive appearance of the lesions, several other conditions must be considered in the differential diagnosis of PPD, including: leukocytoclastic vasculitis, drug hypersensitivity reactions, purpuric contact dermatitis, early cutaneous T-cell lymphoma (CTCL), stasis pigmentation, scurvy, purpuric generalized lichen nitidus, actinic purpura, thrombocytopenia, self-induced hematomas, Waldenström, hypergammaglobulinaemic purpura, Henoch-Schönlein purpura, and Kawasaki disease [2, 6]. Apart from confirming the diagnosis of a PPD, a skin biopsy is useful in excluding CTCL, which in its early stages may closely mimic a PPD both clinically and histologically [7], or even develop in patients with persistent PPD [8]. Given the similarities between these conditions, Toro et al. tested for clonality of the T-cell population using a polymerase chain reaction (PCR) assay. This group found that, possibly, the lichenoid variants of persistent PPD are biologically related to mycosis fungoides [7]. In the same way, the phenotypic and molecular studies performed in patients with PPD by Magro et al. confirmed that PPD may represent a form of cutaneous T-cell lymphoid dyscrasia, based on the frequency of monoclonality, the preservation of persistent T-cell clonotypes, and the extent of pan-T-cell marker loss [9]. Hence, stratification of lesions of PPD according to the molecular profile may be of significant value prognostically and influence therapeutic intervention [9].
Although PAT is usually benign and self-limited, with involution in the course of a year, it may persist for years and be associated with frequent recurrences, resulting in patient distress. Regarding the treatment, it is mainly based on postural measures to improve venous return and edema, such as leg elevation and compression stockings. Other interventions are usually not required. In the case of associated itching or eczema, topical corticosteroids and antihistamines may be useful. Other therapies should be reserved for patients with highly symptomatic disease, refractory to the basic measures. Given the rare nature of this condition, there are sparse reports of successful treatment options. These include pentoxifylline, griseofulvin, ascorbic acid, isoflavones, rutoside, cyclosporine, colchicine, and PUVA [2, 3, 6]. Methotrexate is a recently reported therapeutic alternative for severe or refractory cases [6]. Its efficacy supports an immunologic etiology of PAT. In our case, the benign nature of the disorder was explained and the patient was advised to maintain leg elevation, use compression stockings, and apply a topical steroid cream in the pruritic areas. Gradually, the lesions faded out with no residual dyschromia or scar.
Follow-up consultation is required for cases where there are initial diagnostic uncertainties, particularly to exclude mycosis fungoides. Recently, Hoesly et al. developed a stepwise approach for the diagnosis and treatment of PAT [6].
© 2010 Dermatology Online Journal