Mixed connective tissue disease

Mixed connective tissue disease (MCTD) is a connective tissue disease that simultaneously or sequentially presents mixed manifestations of systemic lupus erythematosus, dermatomyositis or polymyositis, scleroderma, rheumatoid arthritis, etc., without being identifiable as any single one of these diseases. It is characterized by high titers of speckled pattern fluorescent antinuclear antibodies and anti-ribonucleoprotein (n-RNP) antibodies in the blood, with less renal involvement, good response to corticosteroids, and a favorable prognosis. This disease was first reported by Sharp et al. in 1972. There are still differing opinions on whether MCTD is an independent disease. Some consider it a subtype of SLE, or suggest it is a subtype of PSS, but there are also many cases that, after years of observation, show unchanged symptoms and are recognized as an independent disease.