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Byte+: HCT: Pulmonary and Infectious Late Effects.
A 38-year-old male 2 years post-allogeneic HCT presents with a dry, non-productive cough and progressive exertional dyspnea. He has a history of cutaneous cGVHD. Pulmonary function tests reveal an FEV1/FVC ratio of 0.60 and a decline in FEV1 of 25% from baseline, while chest imaging shows air trapping but no infiltrates.
High Yield Points:
-Obstructive pattern + cGVHD history --> Suspect Bronchiolitis Obliterans.
-Chronic Lung Allograft Dysfunction (CLAD) includes BOS and RAS.
-Pulmonary complications --> #1 cause of late NRM in Autologous HCT.
-Immune reconstitution takes 12-18 months (slower in Allo).
-Asplenia (functional/surgical) --> risk of encapsulated bacteria.
-Encapsulated bugs: S. pneumoniae, H. influenzae, Neisseria.
-Loss of immunity --> requires re-vaccination post-transplant.
Additional Concepts:
-Restrictive Allograft Syndrome (RAS) --> fibrotic phenotype of CLAD distinct from airflow obstruction.
-Risk of infection prolonged by GVHD, HLA-mismatch, T-cell depleted grafts.
-Reactivation of latent viruses (VZV, CMV) --> risk years post-transplant.
-Intra-erythrocytic parasites (Babesia) --> risk in asplenic patients in endemic areas.
-Pulmonary symptoms --> may represent relapse, secondary cancer, or infection; broad differential required.
Condition | Key Features | Association |
Bronchiolitis Obliterans (BOS) | Airflow obstruction, air trapping | Pulmonary cGVHD |
Restrictive Allograft Syndrome | Restriction, fibrosis | Pulmonary cGVHD |
Infectious Pneumonia | Fever, infiltrates | Immune suppression / Asplenia |
Secondary Malignancy | Nodule/Mass | Prior TBI / Smoking |
Key insights: Pulmonary complications are a leading cause of late morbidity, with Bronchiolitis Obliterans Syndrome (BOS) being the classic manifestation of pulmonary cGVHD. Clinicians must also remain vigilant for infections due to functional asplenia and delayed immune reconstitution, necessitating strict adherence to re-vaccination protocols.
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Ranjan Pathak
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