Bronchiolitis obliterans with organizing pneumonia (BOOP) heralding anti-Jo-1-positive polymyositis

We report a 51-year-old man who presented with 3 weeks of polyarthritis wit h fever, nonproductive cough, bibasilar crackles, tachypnea, and hypoxia. I nitial laboratory data showed an increased erythrocyte sedimentation rate, rheumatoid factor, and anti-Jo-1 antibody. Imaging studies showed bilateral lower lobe infiltrates of the lung. A transbronchial biopsy specimen revea led characteristic findings for bronchiolitis obliterans organizing pneumon ia (BOOP). About 6 months later, he developed profound proximal muscle weak ness with a dramatic increase in creatine phosphokinase and aldolase and a further elevation of anti-fo-l. Muscle biopsy specimen findings were consis tent with polymyositis. This represents an unusual case in which BOOP occurred at the onset of an i llness initially suggestive of rheumatoid arthritis (RA). The anti-Jo-1-pos itivity led to close follow up and later discovery of evolution into polymy ositis. BOOP can be an early feature of polymyositis as well as RA.