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What is Iris lesion is seen in and explain in detail?
Erythema multiforme(EM) is an acute ,self limiting skin disease charecterised by the abrupt onset of symmetrical target lesions. Erythema multiforme is a skin reaction that can be triggered by an infection or some medicines. The classic lesions are iris or target lesions which are less than 3 cm in diameter, rounded and have 3 zones:central area of dusky erythema, middle paler area of oedema and an outer ring of erythema with well defined margin. Sites: commonly the extremities and the face, but face,trunk ,oral and genital mucosa may be affected. There are two forms: EM major and EM minor. Ref Harrison 20th edition pg 1235, Fitzpatrick 8thednpg 434)