Pulmonary Complications Following Bone Marrow Transplantation

The differential diagnosis for pulmonary complications following bone marrow transplantation (stem cell transplantation) can be narrowed based on timing. Chest radiography is the mainstay of radiologic evaluation, but HRCT can demonstrate a significant pulmonary abnormality in 10% of immunosuppressed patients with normal chest radiographs.

Time	Infectious	Non-infectious
Neutropenic (<30 d)	Invasive aspergilosis, Candida	Pulmonary edema, Drug reaction, DAH
Early (30-100 d)	CMV, PCP	Engraftment syndrome
Late (>100 d)	Uncommon	OB, COP, GVHD
CMV=cytomegalovirus, COP=cryptogenic organizing pneumonia, DAH=diffuse alveolar hemorrhage, GVHD=graft-versus-host disease, OB=obliterative bronchiolitis, PCP=Pneumocystis jirovecii pneumonia

During the neutropenic phase, non-infectious causes comprise between 50% to 80% of pulmonary complications. Pulmonary edema is seen in up to 65% of patients.

DAH is now uncommon, but has an associated mortality of up to 100%. Chest radiographs may reveal bilateral areas of predominantly perihilar and lower lung ground-glass and patchy consolidation. There is rapid deterioration.

The differential considerations change after engraftment. The return of neutrophils makes bacterial and fungal infection less common, and CMV and other viruses become the dominant pathogens. PCP is now less common due to availability of PCP prophylaxis.

Engraftment syndrome refers to diffuse alveolar damage following bone marrow transplantation in the absence of an infectious etiology. The chest radiographs may reveal bilateral pleural effusions, transient pulmonary infiltrates, and interstitial pulmonary edema.

Obliterative bronchiolitis (OB) is the most common noninfectious respiratory complication after hematopoietic stem cell transplantation, occurring in up to 20% of cases. Chest radiographs may reveal signs of hyperinflation, recurrent pneumothorax and occasional focal/diffuse opacities. There may be bronchial dilatation, bronchial wall thickening, peripheral vascular pruning and mosaic attenuation with air trapping on expiratory scans on HRCT.

References

TM, Moss HA, Robertson RJ, Barnard DL. Pulmonary complications following bone marrow transplantation. Br J Radiol. 2003 Jun;76(906):373-9.