Snapshot A 33-year-old male presents to his physician complaining of several red lesions on his palms, back of hands, and on his lips. His past medical history is significant for recurrent herpes. Introduction Hypersensitivity reaction of the skin Common, acute mucocutaneous disease with classic target-shaped lesions with symmetric distribution Divided into erythema multiforme (EM) major and minor login to view 2 more bullets Causes login to view 7 more bullets Often affects young adults (18 - 30 years old especially) Distinct from SJS/TEN, which is a more severe mucocutaneous reaction that is usually caused by a medication Presentation Skin login to view 12 more bullets Must also examine mucosal surfaces and eyes login to view 3 more bullets May have systemic signs (e.g., fever, prodrome) Evaluation Diagnosis is based on symptoms and clinical history login to view 1 more bullet Differential SJS/TEN (flat lesions, tender, always with mucous involvement, + Nikolsky sign) Urticaria (annular lesions) Erythema nodosum Viral exanthems Treatment EM major login to view 2 more bullets EM minor – usually self-limited login to view 1 more bullet Treat underlying cause if identified login to view 1 more bullet Prevention Prevention login to view 3 more bullets Complications Usually none associated with EM minor Potential ocular complications with EM major Prognosis Typically self-limited