[A case of polymyositis with anti-Jo-1 antibody preceded by BOOP]

A 56-year-old man experienced dyspnea since August 1995 and the chest X-ray film showed abnormal shadow. The diagnosis of bronchiolitis obliterans organizing pneumonia (BOOP) was established based on the histological findings of transbronchial lung biopsy. The patient was treated with prednisolone and symptoms improved. Myalgia and muscle weakness developed associated with relapse of BOOP after withdrawal of prednisolone. Patient was admitted to our department on December 1995 for further examination. An increased level of serum CPK, histological findings of muscle biopsy consistent with myositis, and positive anti-Jo-1 antibody were identified. Those findings supported a diagnosis of polymyositis (PM), and BOOP was considered as a pulmonary complication of PM. Myositis and pulmonary lesion improved after second course of steroid therapy and patient was discharged on May 1996. Both chronic pulmonary fibrosis and acute progressive interstital pneumonia are well known as pulmonary lesion associated with PM. The former is frequently recognized in cases of PM with anti-Jo-1 antibody and the latter is often observed in cases without autoantibodies. The association of PM and BOOP, however, has rarely been reported. The findings that BOOP frequently preceded PM and anti-Jo-1 antibody was positive in half of the cases were observed in the literature.