Clinical picture: bronchiolitis obliterans with organising pneumonia during interferon beta-1a treatment

A 49-year-old man with an 8-year history of multiple sclerosis was prescribed treatment with interferon beta-1a (IFN(beta)-1a) (Avonex, Biogen), 30 mg per week. 3 months later he presented with a progressive, unproductive cough and right hemithoracic pain without fever. Full blood count showed slight leucocytosis (13x10^sup 9^ cells/L) with 75% neutrophils. The erythrocyte sedimentation rate was raised (50 mm/h).