Interstitial lung disease, a common manifestation of early onset polymyositis and dermatomyositis

ABSTRACT

This study included 30 patients [17 with polymyositis and 13 with dermatomyositis], they were 12 males and 18 females with a mean age 47 +/- 2.9 years and the aim of this work is to study the polymyositis- dermatomyositis associated interstitial lung disease [ILD] in the newly diagnosed cases .All patients were subjected to Thorough medical history taking, complete clinical examination, Electromyograhpy, muscle biopsy, Spiro metric pulmonary function tests, arterial blood gas analysis [ABG], plain x-ray chest, high resolution computerized tomogram [HRCT] on chest, lung biopsy either fine needle aspiration under computed tomography [C.T.] guidance for 12 patients or trans- bronchial lung biopsy for 7 patients [Total number 19 patients who showed clinical and radiological picture compatible with ILD] and biochemical and auto antibody analysis for Serum creatine kinase [CK], alanine and aspartate amino transferrase [ALT,AST], lactate dehydrogenase [LDH], Rheumatoid factor [RF], antinuclear antibodies [ANA] and antihistidyl-tRNA synthetase [anti- Jo-1]. Pulmonary manifestations alone presented by 20% of patients as initial manifestations, 19 out of the thirty patients proved to have interstitial lung disease. The majority were having non specific interstitial pneumonia NSIP [15 patients, 78.95%]. Our results showed that only 12 out of 30 patients had positive muscle biopsies findings and EMG changes of myositis. The anti Jo-1 antibody was more significant in patients with ILD than those without ILD [p>0.05]. Regarding the radiological abnormalities HRCT was more sensitive than x-ray in detecting such abnormalities and the most common abnormality was irregular linear opacities. The pulmonary function tests and chest radiological abnormalities were significantly correlated with both duration of disease and anti Jo-1 antibody [p> 0.05 and > 0.001 respectively]. ILD was frequently seen in patients with early onset polymyositis [PM] and dermatomyositis [DM]. PM/DM may be initially manifested with pulmonary manifestations. The anti Jo-1 antibody is significantly correlated with pulmonary function tests as well as abnormal radiological abnormalities for patients with ILD