Dermatologic emergencies.

Life-threatening dermatologic conditions include Rocky Mountain spotted fever; necrotizing fasciitis; toxic epidermal necrolysis; and Stevens-Johnson syndrome. Rocky Mountain spotted fever is the most common rickettsial disease in the United States, with an overall mortality rate of 5 to 10 percent. Classic symptoms include fever, headache, and rash in a patient with a history of tick bite or exposure. Doxycycline is the first-line treatment. Necrotizing fasciitis is a rapidly progressive infection of the deep fascia, with necrosis of the subcutaneous tissues. It usually occurs after surgery or trauma. Patients have erythema and pain out of proportion to the physical findings. Immediate surgical debridement and antibiotic therapy should be initiated. Stevens-Johnson syndrome and toxic epidermal necrolysis are acute hypersensitivity cutaneous reactions. Stevens-Johnson syndrome is characterized by target lesions with central dusky purpura or a central bulla. Toxic epidermal necrolysis is a more severe reaction with full-thickness epidermal necrosis and exfoliation. Most cases of Stevens-Johnson syndrome and toxic epidermal necrolysis are drug induced. The causative drug should be discontinued immediately, and the patient should be hospitalized for supportive care.