Erythema

Erythema (Gr. eruthainō, 'I redden'), a name applied to certain skin diseases, but scarcely used by any two writers on the subject in exactly the same sense. It is used, generally speaking, of eruptions where there is circumscribed or diffuse redness, without any break in the skin surface, with or without elevation of the affected part. The chief forms described under the name are rashes like a persistent blush occurring in the course of some fevers, in consequence of drugs, or without ascertainable cause, but usually of short duration: E. multiforme, where the eruption is raised, and generally in the form of papules, rings, or irregular lines; E. nodosum, consisting of dark-red, painful swellings, usually on the front of the leg, and believed to be connected with the rheumatic diathesis; and cases closely resembling erysipelas, except that the symptoms, both local and constitutional, are very much less severe.