Phototesting in lupus erythematosus tumidus - Review of 60 patients

Photosensitivity is an important characteristic feature of several forms of lupus erythematosus (LE), and induction of skin lesions by UV-A and UV-B i rradiation has been proved to be an optimal model for evaluating light sens itivity in patients with this disease. Because lupus erythematosus tumidus (LET) has rarely been documented in the literature and is often difficult t o differentiate from other photodermatoses such as polymorphous light erupt ion, we performed photoprovocation tests in 60 patients with LET according to a standardized protocol. Areas of uninvolved skin on the upper back were irradiated with single doses of UV-A (100 J/cm(2)) and/or UV-B (1.5 minima l erythema dose) daily for three consecutive days. Interestingly, patients with LET are more photosensitive than those with subacute cutaneous lupus e rythematosus, and in our study experimental phototesting revealed character istic skin lesions in 43 patients (72%), Because of the latency period in d eveloping positive phototest reactions, it might be difficult for these pat ients to link sun exposure with their skin lesions. Furthermore, our data r evealed a positive correlation of antinuclear antibodies and positive provo cative phototest reactions in these patients as seen for other forms of LE, In conclusion, the high incidence of positive phototest reactions in corre lation with the clinical findings, history of photosensitivity and antinucl ear antibodies enable the classification of LET as the most photosensitive type of LE.