[Photobiological study of lupus erythematosus]

Although cutaneous photosensitivity is one of the major criteria used for the diagnosis of systemic lupus erythematosus, this criterion is not precise.

To evaluate the interest of photobiological exploration in patients with cutaneous lupus erythematosus, and to compare the results to clinical photosensitivity.

Nineteen patients consecutively seen in one year, have been tested using a standardized method.

Clinical photosensitivity was present in 16 cases. The clinical presentation of cutaneous disease was classified in 3 groups: acute, subacute, and chronic. One patient with no history of photosensitivity had positive photobiological tests, and five patients had negative tests though they experienced clinical photosensitivity. Positive phototests with UVA and UVB were present in 6/8 subacute lupus cases, 3/6 acute lupus cases, 3/5 chronic lupus cases. Histological aspect of cutaneous biopsies from phototest was not characteristic of lupus. Minimal erythematous doses was comparable in lupus group and in controls. No correlation between positivity of phototests and the presence of systemic involvement or anti-Ro/SSA antibodies was established.

Phototesting is useful to assess photosensitivity in lupus patients.