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DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms), Stevens-Johnson Syndrome (SJS), and Toxic Epidermal Necrolysis (TEN) are severe, life-threatening drug hypersensitivity reactions characterized by extensive skin involvement and systemic manifestations. These conditions represent a spectrum of cutaneous adverse drug reactions with SJS and TEN distinguished by the extent of skin detachment (<10% vs >30% body surface area respectively). Early recognition and immediate discontinuation of the offending agent are critical for patient survival.
These reactions involve complex immune-mediated mechanisms including delayed-type hypersensitivity (Type IV) reactions mediated by drug-specific T-cells. In SJS/TEN, cytotoxic T-lymphocytes and natural killer cells release cytolytic proteins like granulysin, perforin, and granzyme B, leading to widespread keratinocyte apoptosis and epidermal detachment. DRESS involves a different pathway with eosinophil activation, cytokine release, and multi-organ involvement due to widespread immune activation and inflammation.
Clinical diagnosis relies on recognizing the characteristic timeline (typically 1-8 weeks after drug initiation for DRESS, 4-28 days for SJS/TEN), distinctive skin findings (morbilliform rash with facial edema in DRESS vs target lesions and mucosal involvement in SJS/TEN), and systemic features. Laboratory findings including eosinophilia and atypical lymphocytes support DRESS diagnosis, while skin biopsy showing full-thickness epidermal necrosis confirms SJS/TEN. Immediate drug discontinuation, supportive care in specialized units, and consideration of immunosuppressive therapy are essential management steps.