FIGURE 68.9 Erosions on the lips with target lesions on the hands (Reprinted with permission from Somolinos AL, Grant LM, Goldsmith LA, et al VisualDx: Essential Dermatology in Pigmented Skin Philadelphia, PA: Lippincott Williams & Wilkins; 2011.) Stevens–Johnson Syndrome/Toxic Epidermal Necrolysis SJS and toxic epidermal necrolysis (TEN) are clinically similar, but exist in a spectrum distinguished by the degree of skin involvement SJS involves 30% of body surface area; and 10% to 30% body surface area involvement is considered SJS/TEN overlap A prodrome of fever and constitutional symptoms (malaise, headache, sore throat, myalgias, arthralgias) sometimes precedes the onset of cutaneous lesions Erythematous and purpuric macules start on the face and trunk and spread over hours to a few days to become more confluent and bullous Tender erosions remain after the bullae rupture ( Fig 68.10 ) As the erythematous macules develop dusky centers indicating epidermal necrosis, they can have a targetoid appearance but lack the classic three zones seen in the target lesions of EM Gentle lateral pressure to an area of macular erythema causes the epidermis to sheer off, known as the Nikolsky sign Postinflammatory dyspigmentation is common Mucous membrane involvement can precede cutaneous involvement by to days Two or more mucosal surfaces are usually involved, while any epithelial