Phototests in patients with various forms of lupus erythematosus.

Responses to ultraviolet B (UVB; 290-320 nm) were tested in 227 patients with main forms of lupus erythematosus (LE): discoid LE (DLE), discoid disseminated LE (DDLE), systemic LE (SLE), and subacute cutaneous LE (SCLE). Four parameters were evaluated: minimal erythema dose (MED), its distribution, persistence of erythema, and photoreproduction of lesions. Patients with LE differed considerably from controls in their UVB reactivity. In addition, there were significant differences between various LE forms, even after a single UV exposure. Lowered MED in comparison to controls was observed most frequently in SLE patients (64.4%) and least frequently in DLE patients (32.1%). Prolonged persistence of erythema induced by 1-2 MED was a constant finding in SCLE. In SLE and DDLE, it was observed in more than 80% of patients, and in DLE in 56.7% of examined cases. Photoreproduction of lesions after single UVB exposure was observed most frequently in SCLE (62.5%) and only in 10% of DLE patients.