Bronchiolitis obliterans syndrome (BOS) remains a major complication after lung
transplantation, causing significant morbidity and mortality in a majority of recipients. BOS is
believed to be the clinical correlate of chronic allograft dysfunction, and is defined as an
obstructive pulmonary function defect in the absence of other identifiable causes, mostly not
amenable to treatment. Recently, it has become clear that BOS is not the only form of chronic
allograft dysfunction and that other clinical phenotypes exist; however, we focus exclusively …