Endogenous photodermatosesPolymorphous Light Eruption (PMLE)- Acquired photo-induced disease presenting in mainly second or third decade; often seen in spring or early summer; most common form of idiopathic photodermatitis
- Likely due to delayed hypersensitivity reaction to endogenous photo-induced antigen
- Presents typically with patchy erythematous papules, plaques or vesicles within minutes to hours (sometimes days) of UV exposure in sun-exposed sites; improves as summer progresses (natural ‘hardening’)
- Juvenile spring eruption: PMLE variant in boys or young men with involvement of ears (helices) typically
- Histology: superficial and deep lymphocytic perivascular infiltrate with striking papillary dermal edema
- Treatment: topical or oral corticosteroid; overall treatment includes high SPF and restriction of UVR exposure, low dose NBUVB, PUVA or antimalarial
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