Diagnosis of lupus nephritis by skin immunofluorescence, in the absence of extrarenal manifestations of systemic lupus erythematosus.

Six patients with glomerulonephritis were found to have granular deposits of complement and/or immunoglobulins at the dermalepidermal junction of normal skin. No patient had extrarenal clinical manifestations of systemic lupus erythematosus (SLE). The only serologic test suggestive of SLE was a positive antinuclear antibody (ANA) reaction; results of complement and antinative deoxyribonucleic acid (DNA)-antibody tests were repeatedly normal. The patients with glomerulonephritis had a favorable initial response to therapy with prednisone with or without azathioprine. These patients may represent a variant of SLE in which the diagnosis can only be established by a direct immunofluorescence test of normal skin. Alternatively, they may constitute a separate new clinical entity. Because of the favorable response to therapy, we suggest that skin immunofluorescence be performed in patients who present with unexplained glomerulonephritis and a positive ANA.