Phototesting in lupus erythematosus.

Ultraviolet (UV) irradiation is a major factor in the pathogenesis of certain variants of cutaneous lupus erythematosus. Photosensitivity constitutes one of the criteria of the American Rheumatism Association for the diagnosis of systemic lupus erythematosus, which further emphasizes its importance. The pathomechanism of UV-induced lupus erythematosus remains unknown. The characterization of photosensitive subacute cutaneous lupus erythematosus (SCLE) by Gilliam and Sontheimer has led to a new approach. Through the development of standardized test methods it has became possible to reproduce cutaneous lesions in the UV-A and UV-B spectrum. These standardized test methods allow a better definition of photosensitivity than clinical history does. Recent clinical data show that besides SCLE another variant, lupus erythematosus tumidus, also reveals pronounced photosensitivity. In this review article phototest procedures, phototest results, and clinical correlations in different subgroups are discussed.