Dermatology Image: Erythema Multiforme
Fall 2011 - Volume 15 Number 4
Erythema multiforme (EM) is a type of delayed hypersensitivity skin reaction triggered by infection or certain drugs.1 It consists of a polymorphous eruption of macules, papules, and characteristics target lesions (central bullae or vesicle with surrounding concentric rash) distributed with a propensity for the distal extremities.2 Although the more severe conditions of Steven-Johnson Syndrome and toxic epidermal necrolysis (TEN) may represent the same process, EM, with its minimal mucous membrane involvement and less than 10% epidermal detachment, now is accepted as a distinct condition. Possible infectious causes of EM include herpes simplex virus (HSV), adenovirus, measles, mycobacterium, yersinia, and treponema pallidum.1 Medications most often associated with EM include barbiturates, hydantoins, nonsteroidal anti-inflammatory drugs, penicillins, phenothiazines, and sulfonamides.3 In more than 50% of cases of EM no underlying cause is found.1 EM is a clinical diagnosis. Skin biopsy is not necessary when the clinical picture is clear, as biopsy findings in EM are nonspecific.2 Management of EM involves determining the etiology, when possible, and treating the suspected infection or discontinuing the causal drug. Oral antihistamines and topical steroids may be used to provide symptom relief in mild cases of EM, whereas oral prednisone for one to two weeks followed by a taper may be used in patients with more severe presentations.4
1. Loh KY. A 'target‘ skin lesion. Aust Fam Physician 2008 Nov;37(11):946.