Pemphigus foliaceus in a 13-year-old child

Abstract Pemphigus foliaceus (PF) is an autoimmune blistering disease caused by autoantibodies against desmoglein 1, which cause acantholysis and intraepithelial blisters. PF classically presents in adults and, excluding the endemic form of PF (fogo salvagem) found in North Africa, Turkey and South America, it rarely occurs in children. We present a previously fit and well 13-year-old girl who was referred with a 2-year history of multiple small blisters on the legs which gradually spread to the trunk and arms. Concomitantly she had severe abdominal pain and alternated constipation with diarrhoea. A skin biopsy suggested a diagnosis of PF. She was commenced on azathioprine which had to be subsequently discontinued due to severe muscle pain and fatigue. She has had a 15-month-course of oral prednisolone which was difficult to wean due to acute flares. A repeat biopsy showed features of pemphigus, direct immunofluorescence showed intercellular deposition of IgG and C3 in the epidermis and ELISA revealed positive autoantibodies against desmoglein 1 (110 U mL–1), in keeping with PF. She was commenced on erythromycin with small improvement and was therefore switched to azithromycin which was discontinued after 5 days due to severe abdominal pain. No abnormalities were seen on a colonoscopy and upper gastrointestinal endoscopy. Despite treatment with erythromycin and topical tacrolimus she continued experiencing acute flares, particularly over her chest and back. Dapsone 50 mg once daily was prescribed and was increased to 75 mg to fully resolve the skin lesions. She is under follow-up and her disease has now remained quiescent for a year.