Thymic enlargement in children.

The presence of an anterior mediastinal mass in an infant or child is a diagnostic and therapeutic challenge. Few papers in the literature specifically address subtypes of thymic tumors in the pediatric population and their treatment. Our purpose was to determine which children are at significant risk of having a malignant thymic tumor. Four children were younger than 18 months old. Of these, two (50%) had respiratory distress from tracheal compression although all four had benign tumors. Of the 14 older children, only two were symptomatic, both of these from myasthenia gravis rather than the size of the mass compressing surrounding structures. Four of the 14 masses (29%) were malignant although none of the four were symptomatic. Children with benign tumors lived significantly longer than those with malignant tumors. The significant incidence of malignancy in thymic tumors when the patient is 18 months or older necessitates surgical exploration with complete removal of the mass. Children younger than 18 months require close follow-up and a trial of corticosteroids. Surgery is necessary if the mass enlarges or becomes symptomatic.