Shape and configuration of skin lesions: targetoid lesions.

What is probably the first description of targetoid or iris lesions, as they appear in erythema multiforme (EM), can be found in Thomas Bateman's 1836 textbook "Practical Synopsis of Cutaneous Diseases According to the Arrangement of Dr. Willan." EM was initially described by Bateman and later by von Hebra as an acute self-limiting skin disease, symmetrically distributed on the extremities with typical concentric "targetoid" or "iris" lesions, and often recurrent. Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) were added to this syndrome later. A newer classification has created two disease spectra: EM consisting of EM minor and EM major (or bullous EM), and SJS and TEN. EM minor and EM major are often recurrent, postinfectious (especially after herpes and mycoplasma) disorders with low morbidity and almost no mortality. SJS and TEN are usually severe drug-induced reactions with high morbidity and poor prognosis. The target lesions found in each form of the disease are described and defined. Although the term "target lesion" originated from the description of EM and despite its being the dominant lesion in this disease, it is not pathognomonic for EM, and these lesions can sometimes appear in other diseases. Short descriptions of these other diseases are presented.