LAUSR

Hailey–Hailey disease (HHD) is a rare, autosomal dominant disorder caused by a mutation in one copy of the ATP2C1 gene, which encodes an ATP-dependent calcium pump, thus mutations result in defects in calcium ion binding and transport. HHD typically presents in the third or fourth decade with intraepidermal blistering and changes in keratinocyte adhesion, with symptoms commonly exacerbated by heat and sweating. The management of HHD can be challenging, particularly in recalcitrant cases. There are limited case reports in the literature describing the treatment of HHD with oral retinoids. We present a case of a woman with HHD that responded to treatment with acitretin. A 79-year-old woman presented with a 6-year history of lesions on her thighs, which had not responded to treatment with topical and oral antibiotics and topical antiseptics. Her comorbidities included hypertension, hypercholesterolaemia and overactive bladder syndrome. Her regular medications included amlodipine, simvastatin and oxybutynin. She had initially presented at the age of 58 years with a 4-year history of erosions on the inner labia majora and loss of the labia minora. A biopsy taken at that time showed lichenoid changes, and she was treated with superpotent topical steroids for erosive vulval lichen planus (LP). After an initial improvement in symptoms, the labial erosions became more resistant to treatment, with marked exacerbations particularly in the summer months. On physical examination, the patient was found to have fissuring, blistering and maceration of the upper inner thighs (Fig. 1). These clinical findings were not in keeping with her diagnosis of erosive vulval LP. No nail changes were noted. A familial pattern of skin disease was suspected, as the patient’s daughter presented with similar clinical findings affecting the axilla. Histological examination of a skin biopsy taken from the patient’s upper thigh revealed marked suprabasilar acantholysis with a ‘dilapidated brick wall’ appearance of the keratinocytes. There was preservation of the upper keratinocytes, and no corps ronds or grains were present. Direct immunofluorescence gave negative results (Fig. 2). Based on the clinical and histopathological findings, a diagnosis of HHD was made. Treatment with oral dapsone, with doses up to 50 mg three times daily, in addition to superpotent topical steroids and long courses of oral antibiotics, resulted in only a modest improvement in symptoms. Acitretin 10 mg once daily was commenced, and within 2 months resulted in clearance of the groin maceration and labial erosions (Fig. 3). The disease has remained well controlled on acitretin for a period of 6 years and the patient has reported no adverse effects. Her daughter was also suspected to have HHD, based on (a)