Polymorphous light eruption (PMLE) is a term that describes a group of heterogeneous, idiopathic, acquired, acute recurrent photodermatoses characterized by delayed abnormal reactions to ultraviolet radiation (UVR) and manifested by varied lesions. The various morphologic types include erythematous macules, papules, plaques, and vesicles. However, in each patient the eruption is consistently monomorphous. By far the most frequent morphologic types are the papular and papulovesicular eruptions.
A delayed-type hypersensitivity reaction to an antigen induced by UVR is possible because of the morphology of the lesions and the histologic pattern, which shows an infiltration of T cells. Immunologic studies thus far have not been rewarding except to suggest that a delayed-type hypersensitivity is the probable immunologic basis for PLE. More commonly, UVA is the action spectrum, but PLE lesions have been evoked with UVB and with both UVA and UVB.
The rash usually consists of small red spots or blisters and can appear on any part of the body that has been exposed to sunshine, although commonly the face and the backs of the hands will be spared. It tends to heal without
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