[Lung complications of hematopoietic stem cell transplantation]

Bone marrow transplantation (BMT) is a potentially curative therapy in selected patients with hematologic disorders (acute leukemia, chronic myelogenous leukemia, lymphoma) or solid tumors (testicular or breast cancer). Pulmonary complications occur in 40 to 60% of patients receiving BMT, and are related to various mechanisms: chemotherapy-induced neutropenia, pulmonary toxicity of radiotherapy or chemotherapy, graft-versus-host disease. Bacterial or fungal pneumonia occurring during the initial period of neutropenia, and interstitial pneumonia (related to cytomegalovirus or of unknown origin) are the major respiratory complications of the first 100 days. Bacterial sinusitis and pulmonary infections, and obstructive airways disease related to bronchiolitis are the main late-onset respiratory disorders. No single risk factor can predict the development of these complications, which result from a sequence of events including infections, pulmonary injuries related to chemotherapy or radiotherapy, and inappropriate immunological reaction after transplantation. Antimicrobial prevention has been shown to reduce the mortality of these complications, but they still result in both important morbidity and mortality. They are the most frequent non relapse cause of death among long term surviving patients. Better understanding of their pathogenesis, and early recognition and treatment of respiratory complications of BMT should improve the efficacy of this therapy.