Many photosensitive patients are seen for consultation when they have no lesions, so a detailed history is important. The differential diagnosis is based on the age at which the symptoms first occurred. The striking symptoms and signs are discussed, and advice is given on which additional investigations are necessary and when phototesting must be performed. Guidelines are also given for the performance of phototesting with simple light sources.
Roelandts R. The Diagnosis of Photosensitivity. Arch Dermatol. 2000;136(9):1152-1157. doi:10.1001/archderm.136.9.1152