Its origin may be allergic, seasonal, or drug sensitivity. The characteristic lesion is the target or iris lesion. The condition is acute in onset, and may run a severe course with fatal termination. In mild cases, the eruption is prone to recur. May be associated with rheumatic fever, or it may be evidence of drug sensitivity.
Lesions are self-limiting, but tend to recur.
The appearance of the lesions varies with the type of p., the duration of the lesions, and the acuteness of onset. The color is first red, becoming gradually darker, then purple, fading to a brownish yellow. The mucous membrane of the mouth and fauces is usually also involved. It may be due to a state of hypersensitivity to foods or drugs, foci of infection, or psychic stimuli. H.F. Chambers and Ernest Jawetz.