Dapsone-Induced Hypersensitivity Syndrome in a Patient with Dermatitis Herpetiformis: A Case Report

Dermatitis herpetiformis (DH) is a chronic, intensely pruritic autoimmune blistering disorder strongly associated with gluten sensitivity and celiac disease. Dapsone remains the drug of choice for rapid symptomatic control. However, dapsone may rarely cause dapsone-induced hypersensitivity syndrome (DHS), a potentially life-threatening adverse reaction characterised by fever, rash and internal organ involvement. We report a case of a 48-year-old female diagnosed with DH who developed severe exfoliative dermatitis with mucosal and systemic involvement approximately 5 weeks after initiation of dapsone therapy. She presented with diffuse desquamation, haemorrhagic crusting, oral mucosal erosions and biochemical evidence of hepatic and renal dysfunction. The diagnosis of DH was confirmed before dapsone initiation by perilesional skin biopsy demonstrating granular immunoglobulin A (IgA) deposition in the papillary dermis, along with elevated anti-tissue transglutaminase IgA antibodies. Based on the temporal relationship to dapsone exposure and clinical features, a diagnosis of DHS was made. Prompt discontinuation of dapsone and initiation of systemic corticosteroids led to gradual clinical and biochemical recovery. DHS is a rare but serious complication of dapsone therapy. Early recognition, immediate withdrawal of the offending drug and timely initiation of systemic corticosteroids are crucial to reduce morbidity and prevent life-threatening complications.