Tracheobronchomalacia following allogeneic haematopoietic stem cell transplantation

Tracheobronchomalacia (TBM) occurs due to the weakening of cartilaginous part of the trachea, resulting in compromised airway function and leading to symptoms such as dyspnea, cough, and inability to clear secretions. Bronchiolitis obliterans syndrome (BOS) is the most prevalent late noninfectious pulmonary complication in patients who underwent allogeneic haematopoietic stem cell transplantation (HSCT). Therefore, patients experiencing progressive dyspnea and chronic cough after allogenic HSCT, with new obstructive pattern on pulmonary function test, are typically diagnosed with post-transplant BOS. However, it is important to note that TBM can also manifest as an obstructive defect pattern on pulmonary function test. Tracheomalacia has been reported as a rare complication of allogenic stem cell transplantation. We present two patients who developed TBM following allogeneic HSCT and were initially treated for post-transplant BOS but did not experience symptom improvement. However, after treatment with continuous positive airway pressure, their symptom subsided.