This patient has hard metal disease or cobalt-related interstitial lung disease. The essential elements in making the diagnosis are the appropriate cobalt exposure and the characteristic pathologic findings of giant cell interstitial pneumonia or the discovery of multinucleated “cannibalistic” appearing cells in BAL fluid. This patient is a diamond polisher and uses cobalt-containing tools for diamond polishing. Cobalt is widely used as a hardener and binder in metal alloys of tungsten, aluminum, chrome, and molybdenum. Tungsten carbide, the “hard-metal” that gives this disease its name, is made by mixing minute particles of tungsten, carbon, and up to 25% cobalt, and then sintering the mixture at high temperature to produce an extremely hard and heat-stable alloy. Occupations associated with cobalt-related interstitial lung disease include those associated with the maintenance and resharpening of hard metal tools, the production of hard metals, diamond tooling (grinding wheels and stone saws), work utilizing cemented tungsten carbide (oil well drilling sites), armored plate production (tanks, naval ships), and the manufacture and maintenance (grinding/polishing) of cutting tools and loops for fishing poles. Figure 3
shows thickening of interalveolar septae with chronic inflammatory cells, consistent with an interstitial process, plus giant multinucleated cells with engulfed inflammatory cells lying within air spaces.