Immune-mediated chronic inflammation and fibrosis involving small airways (obliterative bronchiolitis) and interstitial lung tissue, potentially linked to GVHD and conditioning regimens
Target Population
Patients undergoing allogeneic HSCT for hematological malignancies, immune deficiencies, or hemoglobinopathies
Care Setting
Specialized respiratory and transplant centers with access to pulmonary function testing, imaging, bronchoscopy, and multidisciplinary management
Key Highlights
BOS is the only formally recognized pulmonary manifestation of chronic GVHD characterized by new-onset obstructive lung disease with air trapping and obliterative bronchiolitis histology.
Post-HSCT ILD, presenting as restrictive lung disease with various histological patterns (organizing pneumonia, nonspecific interstitial pneumonia, diffuse alveolar damage, lymphocytic interstitial pneumonia, pleuroparenchymal fibroelastosis), often coexists with obliterative bronchiolitis lesions.
ILD after HSCT is strongly associated with acute and/or chronic GVHD and conditioning regimens, raising the possibility that ILD may represent a spectrum of lung chronic GVHD.
Guideline-Based Recommendations
Diagnosis
Perform routine pulmonary function tests pre-HSCT and at scheduled intervals post-HSCT (day 100, 6, 12, 18, 24, 36 months).
Diagnose BOS based on new-onset FEV1 <75% predicted or >10% decline from baseline, obstructive pattern (FEV1/VC <0.7), absence of infection, and no infiltrative opacities on imaging.
Diagnose ILD by presence of infiltrative opacities on HRCT, exclusion of infectious pathogens via BAL, nasal swabs, sputum, and lack of response to antimicrobials; lung biopsy if available to define histologic pattern.
Management
Manage BOS and ILD within a multidisciplinary team experienced in chronic GVHD and pulmonary complications post-HSCT.
Consider immunosuppressive therapy targeting GVHD in ILD cases given strong association with chronic GVHD.
Address conditioning regimen-related risk factors and monitor for early respiratory infections to reduce BOS risk.
Monitoring & Follow-up
Regular pulmonary function testing to detect early lung function decline.
Serial chest CT imaging to evaluate lung parenchymal changes and progression.
Bronchoscopy with BAL for infectious work-up when respiratory symptoms or imaging abnormalities develop.
Risks
Use of peripheral blood stem cells, early lower respiratory tract infections, and early FEV1 decline increase BOS risk.
Conditioning regimens including total body irradiation and cyclophosphamide are associated with post-HSCT organizing pneumonia and ILD.
Chronic GVHD is a major risk factor for both BOS and ILD development.
Patient & Prescribing Data
Allogeneic HSCT recipients developing pulmonary complications (BOS or ILD) post-transplant
Immunosuppressive therapies targeting chronic GVHD may be beneficial in ILD; early detection and management of BOS and ILD are critical to improve outcomes.
Clinical Best Practices
Implement routine and longitudinal pulmonary function testing in all allogeneic HSCT recipients.
Use a comprehensive diagnostic approach including imaging, infectious work-up, and histology when feasible to differentiate BOS from ILD.
Recognize ILD as a potential manifestation of chronic pulmonary GVHD and manage accordingly.
Monitor patients closely for early respiratory infections and lung function decline to initiate timely interventions.
Adopt multidisciplinary care involving hematologists, pulmonologists, radiologists, and pathologists for optimal management.
by Gabrielle Archer, Ingrid Berger, Louise Bondeelle, Constance de Margerie-Mellon, Stéphane Cassonnet, Régis Peffault de Latour, David Michonneau, Sylvie Chevret, Anne Bergeron
