Lamotrigine-Associated DRESS Progressing to Epidermal Detachment
A 34-year-old man is admitted with a 5-day history of fever, facial swelling, and a diffuse morbilliform rash. Three weeks ago he started lamotrigine; the dose was increased rapidly over one week. Examination shows temperature 38.9°C, facial edema, cervical lymphadenopathy, and 60% body surface area erythematous rash without blistering or mucosal erosions. Laboratory results: eosinophils 1.8 × 10^9/L, ALT 180 U/L, AST 140 U/L, creatinine 1.3 mg/dL (baseline 0.9), and atypical lymphocytes on smear. Nikolsky sign is negative. He has no prior drug allergies. Blood cultures are negative. He is hemodynamically stable.
1. What is the most likely diagnosis, and which findings support it? What immediate action is required?
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The most likely diagnosis is DRESS (drug reaction with eosinophilia and systemic symptoms), also called drug-induced hypersensitivity syndrome. Supportive features include a new aromatic anticonvulsant started three weeks earlier with rapid titration, fever, facial edema, lymphadenopathy, eosinophilia, atypical lymphocytes, and hepatic and renal involvement. The negative Nikolsky sign and absence of mucosal erosions argue against Stevens-Johnson syndrome or toxic epidermal necrolysis at this stage. Stop lamotrigine immediately. Avoid other aromatic anticonvulsants such as phenytoin, carbamazepine, oxcarbazepine, and phenobarbital because of cross-reactivity. Admit for monitoring, check HHV-6 and CMV, monitor liver and kidney function, and evaluate for myocarditis if there are cardiac symptoms. Provide supportive care and consult dermatology and allergy/immunology.
2. Should he receive systemic corticosteroids? If so, how would you dose and monitor?
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For DRESS with significant organ involvement, systemic corticosteroids are commonly used despite limited randomized evidence. A reasonable regimen is prednisone 1 mg/kg/day, or intravenous methylprednisolone for severe disease, followed by a slow taper over four to eight weeks. The taper should not be rushed, because relapse can occur when steroids are withdrawn too quickly. Monitor blood glucose, blood pressure, infection, and gastrointestinal symptoms. Continue to follow liver enzymes, creatinine, and blood counts; watch for late autoimmune sequelae such as thyroiditis, type 1 diabetes, and myocarditis. Antiviral therapy is not routinely indicated for HHV-6 reactivation unless the disease is severe and refractory. If steroids fail or organ involvement worsens, involve a multidisciplinary team.
3. On day 3 he develops 10% body surface area epidermal detachment and oral erosions. How does the diagnosis and management change?
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The new epidermal detachment and mucosal erosions indicate Stevens-Johnson syndrome or toxic epidermal necrolysis overlap rather than isolated DRESS, although severe DRESS can rarely evolve. Stop all suspected drugs, transfer to a burn or intensive care unit, and provide supportive care with fluids, temperature control, wound care, and pain control. Obtain ophthalmology consultation urgently for ocular surface protection and monitor for sepsis. Calculate SCORTEN to guide prognosis. Systemic corticosteroids are controversial in this setting; some centers use cyclosporine or etanercept, but evidence is limited and treatment should follow institutional protocol. Avoid unnecessary medications and document the reaction precisely. Long-term avoidance of lamotrigine and cross-reactive aromatic anticonvulsants is essential.