ABSTRACT
Among various dermatological entities, toxic epidermal necrolysis (TEN) is a rare but potentially fatal delayed hypersensitivity reaction to numerous medications. A 38-year-old male presented with systemic hypersensitivity reaction, such as high fever, pain in the eyes, and diffuse pruritic erythematous maculopapular eruptions with multiple targetoid plaques that became vesicular and bullous. Oral mucosa and conjunctivae were involved. The first sign appeared about 1 week after taking methazolamide (50 mg twice a day) for the management of glaucomatous eyes. Although methazolamide was discontinued, blistering and skin denudation progressed to affect up to 80% of the body surface area and a positive Nikolsky sign was noted. High fever also persisted. Skin lesions started to improve after 2 weeks of management and fever subsided. Cutaneous lesions improved with minimal permanent sequele 2 months later. HLA-B*5901 was found by high-resolution genotyping. The lymphocyte activation test performed 6 months after remission showed a positive response to methazolamide challenge. This is the first case of methazolamide-induced TEN in which methazolamide was confirmed as a culprit drug by the lymphocyte activation test.