A 15-year-old female patient presented with a 4-year history of pustular lesions on the proximal region of the upper limbs with a subsequent impairment of the chest and abdomen. During this period, the lesions showed temporary episodes of improvement that evolved with residual hyperchromic macules.
Physical examination revealed pustular lesions with a slightly erythematous base, isolated or grouped in a serpiginous pattern, on the trunk and proximal region of the upper and lower limbs. Hyperchromic macules were observed mingled with pustular lesions. There were no lesions on the face, palms, soles, and mucous membranes (Figures 1 and 2). A complete blood count, serum protein electrophoresis and liver, kidney and thyroid functions showed normal results.
Histopathology revealed a subcorneal spongiform pustule (Figure 3). Direct immunofluorescence of the perilesional skin for IgA, IgM, IgG and fibrinogen was negative, thus excluding IgA pemphigus.
Considering the clinical and histopathological findings, we confirmed the diagnosis of SPD. The patient was treated with dapsone (100mg/day) with a significant improvement after one month, showing only hyperchromic macules and residual crusts (Figure 4). After treatment was instituted we observed a slight increase of total bilirubin (TB = 1.7, DB = 1.2) and a slight decrease of hemoglobin (Hb = 10.7). There were no alterations on the remaining markers of hemolysis and on G6PD dosage. We chose to maintain the treatment and throughout the patient's follow-up all laboratory results remained stable. After complete clinical improvement, dapsone was tapered to 50mg/day and the patient was followed-up every three months. Nine months after treatment was started no flares had been noticed.