Autoimmune Overlap Syndromes

Diagnosing autoimmune diseases is frequently difficult. To complicate matters, some patients have multiple autoimmune disorders with symptoms and diagnostic criteria that overlap.

Overlap syndromes are most likely to occur in autoimmune rheumatic or arthritic diseases and in autoimmune liver diseases. In the disorder known as mixed connective tissue disease (MCTD) patients have signs and symptoms characteristic of systemic lupus erythematosus (SLE), scleroderma, and the inflammatory muscle disorder myositis. Some researchers consider MCTD to be a scleroderma-SLE overlap syndrome. Patients with autoimmune hepatitis often have overlapping conditions of primary biliary cirrhosis or primary sclerosing cholangitis. In overlap conditions, tests for specific autoantibodies are an integral step in diagnosis.