Photosensitivity: results of investigation in 250 patients.

Between January 1972 and December 1974, 250 patients were referred for investigation of possible photosensitivity to a university-associated clinical research unit for photobiology. In addition to an appropriate history and clinical examination, phototesting was carried out with a solar simulator, monochromatic light and fluorescent light directed to patch-tested areas of skin. Photosensitivity was not demonstrated in 110 patients (44%). Among the laboratory-confirmed photosensitivities, diagnoses included polymorphous light eruption (4.4%), erythropoietic protoporphyria (3.6%), porphyria cutanea tarda (2%), photoallergic contact dermatitis (5.6%), persistent light reaction (4%), systemic drug phototoxicity (1.2%), phototoxic contact dermatitis (2%), solar urticaria (0.8%) and photoaggravated dermatoses (7.6%). It is important to establish a precise etiologic diagnosis in patients with photosensitivity in order to treat the disorder specifically or effectively or both.