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 with fever, nonproductive cough, bibasilar crackles, tachypnea, and hypoxia. Initial 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 revealed characteristic findings for bronchiolitis obliterans organizing pneumonia (BOOP). About 6 months later, he developed profound proximal muscle weakness with a dramatic increase in creatine phosphokinase and aldolase and a further elevation of anti-Jo-1. Muscle biopsy specimen findings were consistent with polymyositis. This represents an unusual case in which BOOP occurred at the onset of an illness initially suggestive of rheumatoid arthritis (RA). The anti-Jo1-positivity led to close follow up and later discovery of evolution into polymyositis. BOOP can be an early feature of polymyositis as well as RA.