The specificity and clinical usefulness of the lupus band test.

Granular deposition of immunoglobulin at the dermoepidermal junction is characteristic, but not pathognomonic, of lupus erythematosus. When rigid criteria for the lumpus band test are used, a positive result is highly specific. A positive band test is found in clinically normal skin and lesional skin of systemic lupus patients, and in lesional skin of discoid lupus patients. A positive band test is found infrequently in clinically normal skin of patients with other connective tissue disorders. Cutaneous lupus may be difficult to separate from other morphologically similar disorders. The lupus band test is useful in differential diagnosis because other disorders have either a specific pattern of immunoglobulin deposition or no immunoglobulin deposition. The mechanisms of immunoglobulin deposition at the epidermal basement membrane zone are discussed as well as pertinent clinical correlations of the positive band test.