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What happens to the thymus in children who have undergone a median sternotomy?
Kelly MacDonald1, Stephanie Mackenzie
1Department of Paediatric Radiology, Bristol Royal Hospital for Children, Bristol, UK. agatha@doctors.org.uk
Insights
Most children who undergo median sternotomy for cardiac surgery do not show a regenerated thymus on MRI scans. Residual thymic tissue appears unlikely to regrow into a visible thymus after this procedure.
Area of Science:
- Pediatric Surgery
- Radiology
- Immunology
Background:
- The thymus is a primary lymphoid organ crucial for immune system development.
- Median sternotomy for cardiac surgery often necessitates the removal of most of the thymus.
- The long-term fate of residual thymic tissue after sternotomy is not well understood.
Purpose of the Study:
- To investigate the regeneration of residual thymic tissue after median sternotomy in children.
- To determine if a regenerated thymus is identifiable using Magnetic Resonance Imaging (MRI).
Main Methods:
- Retrospective review of cardiac MRI scans from children under 17.
- Comparison between children who underwent median sternotomy (n=62) and those who did not (n=37).
- Assessment for the presence or absence of an identifiable thymus on MRI.
Main Results:
- An identifiable thymus was present in only 29% (18/62) of children post-sternotomy.
- In contrast, 92% (34/37) of children without prior sternotomy had a visible thymus.
- This difference in thymus visibility between the groups was statistically significant.
Conclusions:
- Residual thymic tissue in most children does not appear to regenerate into a visible thymus after median sternotomy.
- MRI is a valuable tool for assessing thymic presence post-sternotomy.
- Further research may explore the immunological implications of absent thymic regeneration.
Background:
The thymus grows rapidly during fetal life and continues to grow during childhood. When a child undergoes a median sternotomy during cardiac surgery, most of the thymus is removed to gain access to the mediastinum. What happens to the residual thymic tissue in the long term?
Objective:
To test the hypothesis that residual thymic tissue left after sternotomy regenerates into an identifiable thymus and is visible on MRI.
Materials And Methods:
We retrospectively reviewed the cardiac MR images obtained over a 14-month period in all children under the age of 17 years who had undergone a median sternotomy (n=62) to establish the presence/absence of a thymus. We also reviewed the cardiac MR images obtained over the same time period in children who had never undergone open cardiac surgery (n=37).
Results:
In the sternotomy group, 18 patients (29%) had an identifiable thymus on MR images, compared to 92% (n=34) in the nonsternotomy group. This difference was statistically significant.
Conclusions:
The majority of children in the study group did not have a visible thymus on MR images, which suggests that in these children any residual thymic tissue left postoperatively does not regenerate.
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