The utility of the lupus band test on sun-protected non-lesional skin for the diagnosis of systemic lupus erythematosus.

OBJECTIVE The sensitivity and specificity of the lupus band test was evaluated, using three different criteria, on sun-protected non-lesional skin for the diagnosis of systemic lupus erythematosus (SLE). In addition, the sensitivity and specificity of the lupus band test was compared with those of other laboratory tests used in the diagnosis of SLE. METHODS Sun-protected non-lesional skin biopsies from 65 patients (F 50; M 15; mean age 41 yrs.) with specific cutaneous manifestations of lupus erythematosus (LE) and from 18 patients with other dermatologic diseases (F 11, M 7; mean age 40 yrs.) were tested using the direct immunofluorescent technique. RESULTS The sensitivity and specificity of the lupus band test was 10.5% and 97.8% respectively using the strict criterion of the presence of two different immunoreactants. The sensitivity and specificity were 52.6% and 69.5% respectively based on the presence of two different immunoreactants and were 78.9% and 47.8% based on the presence of only one immunoreactant. The highest sensitivity was found for ANA (100%). The specificity of all the laboratory abnormalities was particularly high, varying from 82.8% to 100%, except for ANA antibodies which showed a specificity of 65.2%. CONCLUSIONS A positive lupus band test on sun-protected non-lesional skin (even if showing the presence of only one immunoreactant at the dermo-epidermal junction) represents a useful and specific criterion for identifying patients with LE. However, this test is not useful in distinguishing between cutaneous lupus patients with systemic involvement and those without systemic involvement.