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Bronchiolitis obliterans organizing pneumonia with migratory pulmonary infiltrates.

Bronchiolitis obliterans is an uncommon fibrotic lung disease that primarily affects the small conducting airways, often sparing a considerable portion of the interstitium. The lesion, which can be due to a variety of different causes, results from damage to the bronchiolar epithelium, and the repair process leads to excessive proliferation of granulation tissue [1 ]. It may exist in its pure form, but when the granulation tissue within small airways extends into the alveoli, the disease is called bronchiolitis obliterans organizing pneumonia (BOOP) [2]. The chest radiograph typically shows patchy ground-glass or air-space opacities. These sometimes begin as focal lesions and progress bilaterally over time [3]. We recently encountered a patient in whom migratory air-space opacities were due to BOOP. This appearance has previously been noted, but not emphasized, in the literature [4, 5]. BOOP should be considered in the differential diagnosis of migratory air-space opacities.