These usually begin 1-2 days prior to the onset of the rash. Skin lesions may begin as hot, tender, erythematous morbilliform or discrete macules that rapidly coalesce and become patches of loose skin. The oral mucosa especially is susceptible to inflammation, blistering, and erosion. The vaginal tract epithelium also may be involved. Eye involvement may result in bilateral purulent conjunctivitis, which manifests as edema, crusting, and ulceration with pain and photophobia.
Many patients require ventilatory support because of respiratory failure.
Although the exact pathogenesis of TEN is not understood, most experts agree that it represents an idiosyncratic reaction to a drug or chemical agent. No definitive or specific emergent laboratory tests are indicated. Basic laboratory tests may be helpful in planning symptomatic or supportive therapy. The CBC may reveal leukopenia of uncertain cause. Significant fluid loss may occur.