Skin basement membrane immunofluorescence in rheumatoid arthritis: lack of diagnostic correlation.

Thirty-nine patients with rheumatoid arthritis were studied for the presence of skin basement membrane immunofluorescence. Punch biopsies from normal sun-exposed skin of the forearm were negative for basement membrane immunofluorescence in all cases, except one which was read as questionable. No correlation with serum antinuclear antibody or lupus erythematosus cells was observed. Skin immunofluorescence studies are helpful in differential diagnosis when patients with a clinical picture of rheumatoid arthritis present with serum antinuclear antibodies and lupus erythematosus cells. Positive basement membrane immunofluorescence is strong evidence of systemic lupus erythematosus.