Intrathoracic cystic hygroma in an infant with respiratory failure.

A 6-month-old infant presenting initially with clinical signs of bronchiolitis developed acute symptoms of large airway obstruction and respiratory failure despite treatment for bronchiolitis. Endotracheal intubation and oxygen therapy resulted in immediate and dramatic improvement of respiratory failure. Plain chest radiograph, computerized tomography and surgical biopsy with subsequent histological examination established that the respiratory failure was due to a mediastinal cystic hygroma.