Allopurinol-induced toxic epidermal necrolysis featuring almost 60% skin detachment

RATIONALE: Toxic epidermal necrolysis (TEN) is a life-threatening, immunologically mediated, and usually drug-induced disease. Rarely, clinical pharmacists participating in finding the etiology have been reported. PATIENTS CONCERNS: A 33-year-old male presented to the emergency department with a 1-day history of fever and rash. The patient, being newly diagnosed with gout 10 days ago, received allopurinol at a dose of 250 mg by mouth daily. After 10 days’ exposure to allopurinol, the patient manifested with an “influenza-like” prodromal phase (fever of 38°C, throat pains), which was treated with amoxicillin and nonsteroidal anti-inflammatory drugs of the oxicam type. The next day, he developed a worsening fever of 39.5°C, accompanied by a pruriginous rash all over his body. DIAGNOSIS: On physical examination, we observed coalescing dusky red macules over >60% of his body surface area, with blisters and detachment of large sheets of necrolytic epidermis all over his chest and face. The diagnosis of TEN was confirmed. INTERVENTIONS: The patient recovered following treatment with short-term high-dose methylprednisolone sodium succinate, immunoglobulin therapy, topical medication, and supportive therapy. OUTCOMES: He showed a slow but progressive improvement both in symptoms and cutaneous manifestations. Reepithelization of the skin was achieved after 3 weeks. LESSONS: Drug-induced-TEN is potentially fatal. This case underlines the necessity of asking medication history in detail and detecting related drug gene to correctly identify the cause of TEN.