A 49-year-old woman, with no relevant past medical history, consulted with a 1-year history of asymptomatic lesions, which initially appeared on the upper limbs and later extended to the abdominal area, progressively increasing in size.

Symmetrical and confluent erythematous-brownish macules measuring between 10cm and 20cm in diameter were observed, along with multiple pinpoint petechiae involving the inner regions of the arms and the abdomen, without affecting the midline or the flanks (Fig. 1A and B).

Fig. 1.

Purpuric patches and petechiae on the inner region of the arms (A), abdomen, and flanks (B).

Blood tests, including complete blood count, coagulation studies (PT, aPTT), and peripheral blood smear, ruled out thrombocytopenia and other possible causes of purpura of hematological origin. Anti-HBsAg, anti-HCV, antinuclear antibodies (ANA), and rheumatoid factor (RF) testing were negative.

Dermatoscopy identified red dots and globules on a yellowish-red background (Fig. 2).

Fig. 2.

Dermoscopy.

Histopathological examination revealed the presence of vacuolar interface dermatitis with some necrotic keratinocytes, a perivascular and interstitial lymphocytic infiltrate near the dermoepidermal junction, and erythrocyte extravasation within the papillary dermis (Fig. 3A and B). Perls staining revealed the presence of hemosiderin deposits in the dermis (Fig. 3C).

Fig. 3.

Histopathological study. Hematoxylin–eosin 10× (A). Hematoxylin–eosin 40× (B). Perls stain (C).

What is your diagnosis?

Atypical presentation of Schamberg disease.

The patient was treated with topical corticosteroids, pentoxifylline, and narrowband UVB phototherapy sessions (311nm). One month into therapy, the patient showed a marked reduction in lesion intensity. Further progression is unknown because the patient did not attend subsequent follow-up appointments.

Schamberg disease, also known as progressive pigmented purpura, was first described in 1901. It is considered the most common variant of pigmented purpuric dermatoses. Several triggering factors have been identified, including venous hypertension, certain drugs, autoimmune diseases, intense physical exercise, and infections.1

Clinically, it presents with an eruption of petechiae or purpuric macules over yellow, orange, red, or brown pigmented patches. Although lesions are generally asymptomatic, some patients may experience pruritus. In typical cases, symmetrical involvement of the legs is observed, whereas the trunk, arms, thighs, or buttocks are considered uncommon locations. In addition, lesions with linear, unilateral, and zosteriform distribution patterns have been described.2,3

Involvement of the arms and abdomen in this patient requires differential diagnosis with other purpuric disorders that may affect these areas, including hypersensitivity drug reactions, purpuric contact dermatitis caused by clothing, thrombocytopenic purpura, purpuric exanthema due to viral infections, purpuric mycosis fungoides, and intravascular lymphoma, among others.2

Although the diagnosis of Schamberg disease is fundamentally clinical, dermoscopy and histopathology may be helpful in atypical cases.1 Several dermoscopic patterns have been identified, including a coppery-red pigmented background, structures such as red globules or dots, brown dots, a reticular pigment network, and linear or comma-shaped annular vessels.4,5

Histologically, erythrocyte extravasation within the dermis may be observed along with marked deposits of hemosiderin-laden macrophages and the presence of a lymphocytic infiltrate affecting superficial small vessels.2,4 Perls or Fontana-Masson stains may be used to identify hemosiderin deposits within the dermis, allowing pigmented purpuric dermatoses to be distinguished from other forms of dermatitis.2

Five pathological patterns have been described: lichenoid, perivascular, interface, spongiotic, and granulomatous. The interface pattern described in this case is rare and shows basal vacuolization with dyskeratotic keratinocytes, without other types of inflammatory infiltrates.5

Treatment of atypically localized Schamberg purpuric dermatosis is similar to that of the classic variant. It focuses on controlling signs and symptoms through the use of topical corticosteroids or calcineurin inhibitors. In more extensive cases, systemic drugs such as pentoxifylline, colchicine, rutoside, or ascorbic acid may be considered because of their low rate of adverse effects. On the other hand, cyclosporine, methotrexate, dapsone, minocycline, and tranexamic acid have been used in refractory cases. In addition, some patients have responded successfully to UVA phototherapy, narrowband UVB phototherapy, and intense pulsed light.6

Lesions follow a benign and self-limited course. However, they may evolve chronically with numerous relapses and remissions.1,2

The authors report no conflicts of interest.