Successful treatment of linear IgA disease with salazosulphapyridine and intravenous immunoglobulins.

Abstract

Sir, Linear IgA bullous dermatosis (LABD) is a chronic, autoimmune skin disease characterized by pruritic blisters with subepidermal separation.1, 2 Based on the linear deposition of IgA at the dermoepidermal junction and the absence of other immunoglobulins, LABD has been established as an entity distinct from dermatitis herpetiformis and bullous pemphigoid.3 In LABD, most circulating IgA antibodies bind to the epidermal side of 1 mol L−1 NaCl‐separated human skin and recognize an antigen, LAD‐1, which has been identified as the 120‐kDa ectodomain of collagen XVII/BP180 shed by keratinocytes.4 The aetiology of LABD is not understood. Occasional associations with drug intake, infection, pre‐existing inflammatory bowel disease and lymphoproliferative diseases have been documented.2 We report a 15‐year‐old girl who presented with a 3‐week history of a pruritic bullous eruption especially involving the trunk (Fig. 1) and erosions on the labia majora. Scarring was not detectable, whereas some lesions healed with prominent postinflammatory hyperpigmentation. The patient complained of abdominal pain and weight loss and reported episodes of bloody diarrhoea 3 weeks prior to admission. Skin histology revealed subepidermal blister formation accompanied by a neutrophil‐predominated dermal infiltrate with formation of microabscesses in the papillary dermis. Direct immunofluorescence (IF) microscopy of a perilesional skin biopsy showed linear deposition of IgA and C3 at the dermoepidermal junction. Indirect IF microscopy on human salt‐split skin demonstrated binding of circulating IgA antibodies to the epidermal side. On Western blot analysis of concentrated supernatant from cultured HaCaT cells,5 the patient's IgA autoantibodies labelled the soluble 120‐kDa ectodomain of BP180 (LAD‐1). Based on these findings, the diagnosis of LABD was established. Additionally, occult blood was detected in the patient's stools and colonoscopy showed inflamed mucosa involving the whole colon and rectum. Histological examination revealed severe erosive colitis, while direct IF microscopy of colon biopsies was unremarkable.