Massive thymic hyperplasia in an infant with Beckwith-Wiedemann syndrome.

We report the clinical and postmortem findings in a newborn with Beckwith-Wiedemann syndrome and pulmonary hypoplasia. The infant was found to have a massively enlarged thymus gland that apparently caused pulmonary hypoplasia and respiratory insufficiency. Massive hyperplasia of the thymus gland should be considered in the differential diagnosis of respiratory distress in the Beckwith-Wiedemann syndrome.