Thymic hyperplasia, although not a rare condition in infancy, is usually asymptomatic. We describe an infant presenting in the perinatal period with marked tachypnoea. An enlarged thymus, demonstrated on chest radiograph and CT, was associated with small-volume, non-compliant lungs. Other causes of pulmonary malfunction and maldevelopment were excluded.
Conclusion: Thymic enlargement is unusually associated with neonatal respiratory distress but should be considered in the differential diagnosis.