Obliterative Bronchiolitis

First recognized as an occupational disorder, obliterative bronchiolitis is now the primary noninfectious pulmonary complication of allogeneic hematopoietic stem-cell transplantation and lung transplantation. This review includes an update on recognition, treatment, and prevention. The term “bronchiolitis obliterans” was historically used by pathologists to refer to two distinct patterns of small-airway disease. The first was characterized by intraluminal polyps in the small airways. It was subsequently named bronchiolitis obliterans with organizing pneumonia and, more recently, cryptogenic organizing pneumonia. The second pattern was characterized by subepithelial inflammatory and fibrotic narrowing of the bronchioles, which is now recognized as obliterative bronchiolitis or constrictive bronchiolitis. 1 , 2 To add to the confusion, physicians may use the term “bronchiolitis obliterans syndrome” to denote the occurrence of an obstructive ventilatory defect that occurs after transplantation (Table 1), particularly in patients . . .