Innominate artery and tracheal compression due to aberrant position of the thymus.

A 3-month-old infant with failure to thrive was found on bronchoscopy to have tracheal obstruction thought to be secondary to innominate artery compression. Subsequent diagnostic evaluation with magnetic resonance imaging revealed superior and posterior extension of the thymus with resultant compression of the innominate artery and trachea within the narrow confines of the thoracic inlet. Resection of the aberrantly positioned and enlarged thymus and aortopexy resulted in relief of tracheal compression.