Photosensitivity in lupus erythematosus, UV photoprovocation results compared with history of photosensitivity and clinical findings

Summary Photosensitivity, one of the presenting symptoms in lupus erythematosus (LE), is still poorly defined and varying prevalence figures have been reported. The possibility of a coexisting photodermatosis, especially polymorphous light eruption (PLE), has often not been taken into account. We report the results of ultraviolet A (UVA) and B (UVB) photoprovocation tests in 67 clinically photosensitive patients who had confirmed discoid LE (DLE), systemic LE (SLE) or subacute cutaneous LE (SCLE). The results are compared with a detailed history of photosensitivity and with clinical and serological findings. A pathological photoprovocation reaction, graded as weak, moderate or strong, was induced with either UVA or UVB in 69% of patients with LE, in 100% of those with SCLE, in 70% of those with SLE and in 64% of those with DLE, but in none of 14 controls. Only 16% of the pathological reactions were strong and long‐lasting, resembling LE lesions, while 48% were moderate or weak and transient, clinically like PLE. Fifty‐three per cent of the provocation reactions which were biopsied showed a PLE‐like histology or a non‐specific inflammatory reaction, and most of them were clinically moderate or weak reactions of short duration. In the remaining, mostly clinically strong or long‐lasting reactions, the histology was consistent with LE. A history of sunlight sensitivity did not predict a pathological photoprovocation result but a positive association between the presence of SSA/Ro or SSB/La antibodies and a pathological photoprovocation reaction was found. We have shown that PLE coexists with LE and that both PLE‐ and LE‐like lesions can be induced with UV radiation in LE patients.