Alveolar brush cells in an infant with desquamative interstitial pneumonitis.

A full-term infant developed bilateral pneumothoraces and respiratory distress shortly after birth, despite initially good Apgar scores. Persistent tachypnea, hypoxemia, and a chest X-ray remarkable for diffuse alveolar and interstitial infiltrates prompted a lung biopsy at 4 months of age. The biopsy revealed desquamative interstitial pneumonitis with the unique demonstration by electron microscopy of numerous alveolar brush cells. Respiratory brush cells occur normally in the trachea and bronchi of humans and mammals. Although identical cells have been noted in the alveoli of rats, they have never been reported in the alveoli of humans. We present the first electron microscopical demonstration of the alveolar brush cell in humans.