Electron microscopy of desquamative interstitial pneumonia.

The clinical, radiographical, and physiological picture of two patients suffering from desquamative interstitial pneumonia is described. The diagnosis was established by lung biopsy when the characteristic histological features were found on light microscopy. The dramatic response to adequate corticosteroid therapy is recorded, and attention is directed to the danger of serious relapse on early withdrawal of this treatment and the subsequent satisfactory response to a second course. Electron microscopical studies of the tissue from one patient add materially to the understanding of the clinical course and the nature of the tissue response. At the ultrastructural level the attenuated membranous (type 1) pneumonocytes which normally line the alveoli were replaced by granular (type 2) pneumonocytes. The desquamated intra-alveolar cells comprised two main groups. These were granular pneumonocytes, similar to those lining the alveoli, and smaller numbers of macrophages. The cytopathic effects of virus infection were not detected by light or electron microscopy.