Muscle involvement in mixed connective tissue disease.

Muscle disease has been recognized as a common feature of mixed connective tissue disease (MCTD) since its first description in 1972. In the absence of clinical trials that are directed specifically at the myositis of MCTD, patients should be treated in the manner that is recommended for other forms of myositis. Myositis of MCTD may have a better prognosis than other forms of myositis.