28.1 Introduction
Pigmented purpura refers to a group of benign skin disorders characterized by patches of purpura and petechiae with pigmentation resulting from hemosiderin deposition. The lower extremities are primarily involved. The appearance can be a cosmetic concern for adolescents.
28.2 Epidemiology
Pigmented purpura is relatively uncommon. It is seen in all age groups. The cause is unknown.
28.3 Clinical Findings
At least five different subtypes are described but there may be overlap between these disorders. The subtypes are as follows: (1) Schamberg disease (progressive pigmentary purpura), (2) Majocchi disease (purpura annularis telangiectoides), (3) Lichen aureus, (4) Gougerot-Blum purpura, and (5) eczematoid-like purpura (eczematoid-like purpura of Doucas and Kapetanakis).
Schamberg disease (progressive pigmentary purpura) is the most common variant in children and adolescents. It presents with non-palpable reddish-brown areas of purpura and pigmentation, within which punctate petechiae (“cayenne pepper spots”) are visible (Fig. 28.1).
Majocchi disease (purpura annularis telangiectoides) occurs in adolescent patients and is characterized by petechiae, purpura, and telangiectases in an annular pattern (Fig. 28.2).
Lichen aureus is a subtype of pigmented purpura with few and localized lesions. The pigmentation typically has an orange-yellow hue.
Less common variants have a lichenoid morphology or overlying scale and may be associated with pruritus. Rarely, mycosis fungoides can present with or mimic a pigmented purpuric dermatosis.
Pigmented purpura primarily affects the lower extremities. It occasionally affects the upper limbs and may rarely be generalized. It is usually asymptomatic.
Schamberg disease with reddish-brown areas with petechiae
Purpura annularis telangiectoides
28.4 Laboratory
Histopathology typically shows a perivascular lymphocytic infiltrate with extravasation of red blood cells and hemosiderin deposition in the dermis.
The platelet count and coagulation studies are normal. Laboratory markers of inflammation are not elevated.
28.5 Treatment
Treatment is challenging and not necessary for asymptomatic patients unless there is concern about cosmesis. Topical steroids and calcineurin inhibitors are often prescribed. Narrow-band UVB phototherapy can be helpful in some cases.
28.6 Prognosis
The course is variable. Lesions may persist or recur from several months to many years.