Bronchiolitis Obliterans Following Lung Transplantation and Stem Cell Transplantation in Pediatric Patients

Bronchiolitis obliterans (BO) is a relatively common chronic complication following pediatric lung or hematopoietic stem cell transplantation (HSCT) characterized clinically and physiologically by obstructive lung disease with air trapping and pathologically by obstruction and/or obliteration of smaller airways. It likely represents a "final common pathway" of response to airway epithelial injury from a variety of agents or mechanisms. Bronchiolitis obliterans can have an insidious onset and is difficult to diagnose. Clinical suspicion and recognition of risk factors is important to identify BO since clinical symptoms are often not present at the onset of disease. Currently, there are no specific, effective, and safe treatment options for BO following lung transplantation or HSCT. Therefore, preventing BO is preferable to attempting to treat it. This review will describe the typical features of BO including: diagnostic criteria, epidemiology, radiology, physiology, pathology, prognosis, treatment, and directions for future research.