A New Pathologic Variant of Acute Silicosis in Sandblasters. Characterized by Histologic Features ResembUng Alveolar Profeinosis

Four patients with a rapidly fatal pulmonary illness characteristic of acute silicosis but with uniform histologic features of alveolar proteinosis are described. AU were young men, engaged in sandblasting for an average period of four years. The course of the disease was relentless and uninfluenced by antibiotics, antituberculosis drugs, steroids or intemiption of exposure to silica. The average period of survival after onset of symptoms was 7.5 months. An autopsy in each case showed marked interstitial fibrosis and pneumonitis with a few small silicotic nodules and microscopic evidence of silica in two patients. The unique finding was the presence of proteinaceous material filling the alveolar spaces which gave a positive reaction when stained with periodic acid-Schiff reagent. This latter feature mimicked closely the characteristic histologic changes of pulmonary alveolar proteinosis. Similar responses have been observed in experimental animals exposed to high concentrations of quartz dust. We believe that in this report we have described the first human cases in the English literature which confirm this association.