Hard metal pneumoconiosis: a case of giant-cell interstitial pneumonitis in a machinist.

Pneumoconioses are a group of non-neoplastic pulmonary disorders caused by inhaled inorganic particles. Welldescribed forms of pneumoconiosis include those from asbestos, silica, coal dust, beryllium, and hard metals. Giant-cell interstitial pneumonia is an uncommon pneumoconiosis, usually due to exposure to hard-metal compounds, primarily cobalt and tungsten carbide. The natural course of the disease is interstitial fibrosis and accumulation of giant cells in the alveolar spaces. In 1968, Liebow and Smith developed the original histologic classification for chronic interstitial pneumonias, including giant-cell interstitial pneumonia, usual interstitial pneumonia, desquamative interstitial pneumonia, lymphoid interstitial pneumonia, and bronchiolitis obliterans interstitial pneumonia (diffuse alveolar damage).1 Today it is recognized that most cases of giant-cell interstitial pneumonia are secondary to hard-metal exposure, and the entity is not included in current classifications of idiopathic interstitial lung disease. We present a case of a machinist who demonstrated the diagnostic features of giant-cell interstitial pneumonia.