Hard metal pneumoconiosis: another cause of diffuse interstitial fibrosis.

Three patients developed diffuse pulmonary fibrosis caused by exposure to aerosolized cobalt while working in the tungsten carbide tool industry. Two cases were severe and one of these has died of cor pulmonale. The third is mildly disabled. The pathophysiology is reviewed. Clinicians and radiologists should be aware of hard metal exposure as a cause of diffuse interstitial fibrosis.