Desquamative interstitial pneumonia: relationship to interstitial fibrosis

The clinical course and radiographic and pathological findings in 14 patients having the histological pattern of desquamative interstitial pneumonia (DIP) were studied. Four deaths occurred from cardiorespiratory failure and 2 from other diseases, and one patient had severe pulmonary insufficiency. Seven patients had altered immunological reactivity or arthritis. Necropsy of 3 patients, one who died of respiratory insufficiency and 2 of other diseases, revealed diffuse pulmonary fibrosis with loss of the desquamative features noted on biopsy. One patient had had industrial exposure to tungsten carbide dust and X ray diffraction analysis of the post mortem lung showed high concentrations of this substance. ultrastructural observation and direct immunofluorescent staining of one specimen demonstrated fibrin in the alveolar space, a feature usually regarded as distinguishing DIP from chronic fibrosing interstitial pneumonia. The clinical and pathological observations suggest that the histological pattern recognized as DIP may be a nonspecific reaction to diverse forms of injury, which is not clearly separable from the usual type of diffuse interstitial fibrosis.