Polymorphic light eruption

A 34-year-old woman presented with a photosensitive rash (Figure). With 10 minutes of exposure to sunlight she developed pruritic, erythematous papules following a strict photodistribution. The eruption had a predilection for sites that were usually photoprotected, such as the forearms, décolletage and trunk. Histopathology showed a lymphocytic infiltrate with dermal oedema. Her presentation was in keeping with polymorphic light eruption. The patient was counselled regarding photoprotection and empiric vitamin D supplementation. Annual “hardening” with narrowband ultraviolet B phototherapy or serial graded exposure to winter sunlight was offered, and she was advised to complete short courses of prednisolone during acute flares.