Epidermal IgG deposits in patients with chronic inflammatory connective tissue diseases: diagnostic value and correlation to clinical and immunological parameters in patients with primary Sjögren's syndrome.

Thirty-seven patients with primary Sjögren's syndrome (Primary SS), 12 patients with incipient primary SS, 100 patients with other chronic inflammatory connective tissue diseases (CTD) and 20 healthy controls had a punch biopsy taken from clinically unaffected skin from the buttock. Direct immunofluorescence examinations revealed intraepidermal IgG deposits in 68% of patients with primary SS, in 42% of patients with incipient primary SS, in 13% of patients with rheumatoid arthritis (RA, n = 31), in 15% of patients with systemic lupus erythematosus (SLE, n = 13), in 24% of patients with other well-defined CTD (n = 41), in 40% of patients with ill-defined CTD (n = 15) and in 10% of healthy controls. Immunoglobulin deposits along the dermoepidermal junction zone (DEJ) were not found in any of the patients with primary SS, but were present in 16% of the patients with RA and in 23% of the patients with SLE. In the patients with primary SS, no correlation was found between intraepidermal IgG deposits and age, disease duration, extraglandular manifestations, P-IgG concentration, ANA, rheumatoid factors or circulating immune complexes. Examination for intraepidermal IgG deposits seems valuable in the differential diagnosis between primary SS and RA or SLE, and it could supplement the lupus band test.