Atypical acropustulosis in infancy

A 20‐month‐old white girl had a 4‐month history of an intensely pruritic widespread eruption that began as crops of 1–3‐mm papules and vesicles predominantly on her hands and feet. These lesions evolved into pustules after 24–48 h. Identical lesions would then erupt over large areas of her scalp, trunk, and extremities. Her primary care physician initially interpreted this eruption as chickenpox complicated by impetigo, and also considered a diagnosis of scabies. Antiscabetics, topical steroids, oral antibiotics, and antihistamines failed to control the eruption or alleviate the pruritus which interrupted sleep and her dally activities. The lesions waxed and waned, with new crops developing every 2–3 weeks and fading slowly before the next crop appeared. There was no history of significant exposure to pets or insects. The patient was otherwise in reasonable health and without systemic symptoms. No other children in her day care center nor any family members had a similar eruption. The family history was negative for skin disorders. On physical examination, there was an extensive pustular eruption, most pronounced on the hands and feet (Fig. 1), but also involving the legs (Fig. 2), chest, and scalp, which was remarkable for the confluent, crusted lesions. There was sparing of the intertriglnous areas. Burrows were absent. Cultures of the pustules for fungi and bacteria were negative, as were KOH and scabies preparations. Our clinical impression was acropustulosis of infancy. Because of some unusual features of presentation, namely the late age of onset, the widespread distribution, and the severity of the eruption, we obtained a 3‐mm punch biopsy of an intact pustule from the right foot. Histopathologic examination of the biopsy specimen revealed a subcorneal, unilocular pustule containing small clusters of neutrophils invading the intact epithelium (Fig. 3). Hyperplasia and spongiosis of the surrounding epidermis were also noted. There was a sparse mononuclear infiltrate in the papillary dermis, occasionally in a perivascular distribution. Eosinophils were absent. Periodic acid‐Schiff (PAS) stain was negative for fungal elements. These histologic findings were considered to be representative of acropustulosis of infancy. Prior to starting dapsone therapy, initial laboratory studies, including a complete blood count with differential, platelet count, liver function tests, blood urea nitrogen, creatinine, and G‐6‐PD level, were obtained and determined to be within normal limits. Dapsone therapy was initiated at 1 mg/kg/day for 1 week and then increased to 2 mg/kg/day. She showed a dramatic response to therapy with clearing of all lesions. The dapsone dose was then slowly reduced over the next few months and discontinued after 11 months without recurrence of the disorder. She was carefully monitored and at no time experienced untoward effects from this medication.