Further Observations on Cytoplasmic Hyaline in the Lung

Cytoplasmic hyaline material resembling Mallory's alcoholic hyaline has previously been described in pulmonary alveolar cells of patients with asbestosis. We present 14 new cases of cytoplasmic hyaline found in patients with a variety of processes causing damage to the alveolar lining; these include cases of radiation pneumonia, diffuse interstitial fibrosis, organizing bacterial pneumonia, as well as asbestosis. Hyaline was found only in the setting of an unusual type II cell change, which ultrastructurally appeared to represent squamous metaplasia. We conclude that pulmonary cytoplasmic hyaline is not specific for asbestosis but rather is a nonspecific reaction to injury;