Cutaneous erythematous reaction patterns.

Cutaneous erythematous reaction patterns are signs of hypersensitivity to inciting agents, both endogenous and exogenous. They include erythema multiforme, toxic epidermal necrolysis, erythema nodosum and the figurate erythemas. A thorough evaluation is often necessary to identify the provocative agent. When the cause is not discovered, it is imperative that the physician perform repeat examinations, since serious internal disorders may be associated with some of these reactions.