Respiratory complications in mixed connective tissue disease

The term mixed connective tissue disease is used to identify the patients w ith combined clinical features of systemic lupus erythematosus, scleroderma or progressive systemic sclerosis, and polymyositis-dermatomyositis. A pre requisite for the diagnosis of mixed connective tissue disease is the prese nce, in the serum, of high titers of antibodies against uridine-rich RNA-sm all nuclear ribonucleoprotein (snRNP). Respiratory and nonrespiratory featu res of the disease follow those seen in systemic lupus erythematosus, scler oderma, or progressive systemic sclerosis, and polymyositis-dermatomyositis . Respiratory involvement is observed in 20% to 80% of patients. Major resp iratory manifestations and their incidences described include interstitial pneumonitis and fibrosis (20% to 65%), pleural effusion (50%), pleurisy (20 %), and pulmonary hypertension (10% to 45%). Other pulmonary features consi st of pulmonary vasculitits, pulmonary thromboembolism, aspiration pneumoni a, pulmonary hemorrhage, pulmonary nodules, pulmonary cysts, obstructive ai rways disease, mediastinal lymph adenopathy, pulmonary infections, hypovent ilatory respiratory failure, and diaphragmatic dysfunction. Pulmonary hyper tension is a serious complication; rapid deterioration and death have occur red in spite of corticosteroid and cytotoxic chemotherapy.