Photosensitivity and light eruptions
Reactions to sunlight can be precipitated by drugs (e.g. thiazide diuretics, nalidixic acid), soaps, perfumes, plant pollens, plant contact (e.g. giant hog-weed plant). Most common is a dermatitis-like reaction, but also it may be erythematous or blistering.
Some forms are photosensitive, e.g. erythropoietic protoporphyria (skin burning, redness, swelling, serous crusting +/– subsequent scarring). Treatment is that of the underlying porphyria together with sun protec-tion.
Red papules and herpetiform vesicles or blisters develop, usually in spring, over light-exposed skin, particularly ear helices. Commoner in boys. Lesions heal without scarring. Topical steroids hasten healing.
Itchy, erythematous, papular rash occurring in sun-exposed areas 6–48hr after exposure. Most commonly affects adolescent girls. Treatment is with high factor sun screen.
An uncommon condition precipitated by sunlight. Irritant papules, exuda-tion, and excoriation develop on both exposed and unexposed skin areas. Treatment is with sun protection. Generally resolves after several years.
A rare autosomal recessive condition in which hypersensitivity to sunlight causes marked erythema followed by dry skin, freckles, hyperpigmentation, atrophy, and scarring. Solar keratosis and skin cancers eventually develop due to the decreased ability to repair DNA damaged by UV radiation.