An unusual intrathoracic mass in a patient with developmental delay

Intrathoracic masses may be detected asymptomatically or cause symptoms due to the compression of surrounding normal tissues or organs. Mediastinal masses may be encountered at practically any age and may result from a myriad of causes, and are sometimes detected in otherwise asymptomatic patients. Mediastinal masses are less frequently detected in pediatric patients compared with adult patients, and the spectrum of mediastinal masses in children differs from those encountered in adults. The approach to a mediastinal mass requires careful assessment of the location, appearance, and relationship of the mass to the surrounding structures. The differential diagnostic considerations for mediastinal masses can be broad, but careful assessment coupled with additional directed testing can often narrow the differential considerations. We report the case of a 14-year-old boy with an incidentally detected mediastinal mass at chest radiography that, on further evaluation, led to a very unusual diagnosis. This report highlights the differential diagnoses that were considered for this mediastinal mass and the diagnostic evaluation that led to the final diagnosis.