164 Erythema multiforme
Salient features
History
Examination
• Target-shaped lesions (Fig. 164.1), usually over the palms, soles and skin. A classical target lesion consists of three concentric zones of colour change: typically there is a central, dark, purple area or blister surrounded by a pale, oedematous round zone; this, in turn, is surrounded by a peripheral rim of erythema
• Look at the mucous membranes of the mouth (cutaneous and mucosal lips, gingival sulcus, sides of tongue), nares and conjuctiva (Stevens–Johnson syndrome).
• Tell the examiner that you would like to examine the external genitalia for ulcers.