Linear IgA Disease

Abstract

Linear IgA disease (LAD) is a rare autoimmune blistering disorder affecting both children and adults. It is an acquired, idiopathic disease, but genetic predisposing factors have been identified and in some cases it is triggered by external factors such as drugs or infections. As the name suggests, LAD is characterized by predominant production of IgA autoantibodies against hemidesmosomal and non-hemidesmosomal structures of the basement membrane resulting in subepidermal blistering. The clinical features are various and often resemble other autoimmune blistering diseases, particularly bullous pemphigoid and dermatitis herpetiformis. Skin lesions are typically arranged in grouped, annular or linear patterns forming the characteristic “cluster of jewels” or “string of pearls” signs. Pruritus is a frequent symptom and can be severe. Mucous membranes including the eyes, mouth, oesophagus, and genitalia are often involved and lesions on the mucosa may heal with scarring, causing irreversible and occasionally severe complications. The clinical presentation and histological findings are generally not specific for LAD; therefore, immunopathological examinations are necessary to confirm the diagnosis. The linear IgA deposits along the basement membrane are detectable using direct immunofluorescence microscopy, which is the gold standard for diagnosing LAD and enables differentiation from other autoimmune blistering skin diseases. The first line treatment is dapsone, and the prognosis is favourable in most cases.