Interstitial Lung Disorders After HSCT: A Novel Chronic GVHD Presentation?

Overview

This study compares interstitial lung disease (ILD) and bronchiolitis obliterans syndrome (BOS) as pulmonary complications following allogeneic hematopoietic stem cell transplantation (HSCT). Findings suggest ILD may represent a novel manifestation within the spectrum of chronic graft-versus-host disease (GVHD), sharing clinical and histological features with BOS.

Background

Allogeneic HSCT is a curative therapy for hematological malignancies but is complicated by chronic GVHD, a multisystem disorder causing significant morbidity and mortality. Pulmonary manifestations of chronic GVHD are primarily recognized as BOS, an obstructive lung disease characterized histologically by obliterative bronchiolitis. Recently, ILDs presenting as restrictive lung disease with various histological patterns have been identified post-HSCT, often coexisting with obliterative bronchiolitis. The relationship between ILD and chronic GVHD remains unclear, prompting investigation into whether ILD represents an additional pulmonary manifestation of chronic GVHD.

Data Highlights

A retrospective cohort of 238 HSCT recipients diagnosed with BOS or ILD was analyzed. Pulmonary function tests (PFTs) were routinely performed pre-transplant and at multiple intervals post-HSCT. BOS diagnosis required new-onset obstructive lung disease without infection, while ILD diagnosis was based on infiltrative opacities on HRCT, absence of pathogens, and lack of improvement with antimicrobials. Histological patterns of ILD included organizing pneumonia, nonspecific interstitial pneumonia, and others, frequently coexisting with obliterative bronchiolitis.

Key Findings

• BOS incidence at 3 years post-HSCT was approximately 10%, while ILD incidence was about 5%.
• ILD post-HSCT exhibited restrictive lung disease patterns and diverse histological subtypes, often overlapping with obliterative bronchiolitis lesions.
• Both BOS and ILD were strongly associated with acute and chronic GVHD, suggesting a shared immunopathogenesis.
• Conditioning regimens including total body irradiation and cyclophosphamide were linked to ILD development.
• ILD is not currently recognized as a formal pulmonary manifestation of chronic GVHD but shares clinical and histological features with BOS, raising the possibility of inclusion in the GVHD spectrum.

Clinical Implications

Clinicians should consider ILD as a potential pulmonary manifestation of chronic GVHD in HSCT recipients presenting with restrictive lung disease and infiltrative opacities on imaging. Early differentiation between BOS and ILD using PFTs and imaging is critical for appropriate management. Awareness of conditioning regimen risks and close monitoring for respiratory symptoms post-HSCT can facilitate timely diagnosis and intervention.

Conclusion

ILD following allogeneic HSCT shares clinical, radiological, and histological features with BOS and is strongly associated with chronic GVHD, suggesting it may represent a novel pulmonary manifestation within the chronic GVHD spectrum. Further studies are warranted to confirm this relationship and optimize management strategies.

References

1. Socie et al. 2020 -- NIH Consensus on Chronic GVHD
2. Auclair et al. 2019 -- BOS Incidence and Risk Factors Post-HSCT
3. Ditschkowski et al. 2017 -- Pulmonary Complications After HSCT
4. Vander Lugt et al. 2013 -- Chronic GVHD Diagnostic Criteria
5. Chien et al. 2014 -- ILD Patterns Post-HSCT