Introduction: The authors analyzed the incidence of interstitial lung disease in mixed connective tissue disease. They were seeking an answer to the following problems: the nature of the pathological course of mixed connective tissue disease complicated by and the therapy to be used in interstitial lung disease.
Patients and methods: 179 patients were followed up during a period of 15.9 +/- 6.1 years. Interstitial lung disease was diagnosed using high resolution computed tomography. The diagnosis of interstitial lung disease was not obvious in 5 patients thus open lung biopsy was performed, which confirmed common interstitial pneumonitis. The patients were followed-up, and the data of computed tomography and respiratory function tests were detected 6 months, and then 4 years after the acute lung disease complicated by mixed connective tissue disease.
Results: Out of the 179 mixed connective tissue disease patients 96 (53.6%) had interstitial lung disease. The onset of interstitial lung disease was the most frequent in the 2-4 years of the disease. Four years after the first appearance of interstitial lung disease severe fibrosis was diagnosed in 24 patients (25%). A honey comb formation in the lung developed only in one patient. For the treatment of interstitial lung disease, corticosteroid treatment had to be combined with cyclophosphamide in 51 cases. In 4 patients (24%), pulmonary arterial hypertension evolved 2-4 years following interstitial lung disease. The high pulmonary arterial pressure decreased using pulsed corticosteroid treatment, cyclophosphamide, prostacyclin analogue, anticoagulants therapy and the 4 patients stay alive. The pulmonary arterial hypertension was caused by obliterative vasculopathy.
Conclusion: Pulmonary involvement is found in more than half of the patients with mixed connective tissue disease. Early diagnosis of interstitial lung disease is possible by computed tomography. Interstitial lung disease can be treated by the combination of corticosteroids and cyclophosphamide. The authors were the first to detect the coexistence of interstitial lung disease and pulmonary arterial hypertension in mixed connective tissue disease. Subsequent respiratory alterations in these patient necessitate regular patient follow up.