[Interstitial pneumonia induced by the inhalation of hard metal]

A 51-year-old man visited Okayama Rousai Hospital with the chief complaints of dyspnea and emaciation. His occupational history included 23 years as a hard-metal polisher for a shipyard. Physical examination disclosed digital clubbing and fine crackles audible in the inferior posterior lung fields. Laboratory examination revealed hypoxemia and a remarkably reduced vital capacity of the lungs. Chest x-ray films and computed tomograms disclosed interstitial pneumonia predominantly in the upper lung lobes. Lung fibrosis progressed rapidly, and the patient died of exacerbation of chronic respiratory failure 2 years after his first visit to our hospital. The histopathologic findings from tissue specimens obtained by open lung biopsy and necropsy revealed mixed patterns of atypical and usual interstitial pneumonia, but no giant cell interstitial pneumonia. X-ray analysis detected tungsten in the lung tissue and mediastinal lymph nodes, but no cobalt was found. The interstitial pneumonia observed in this patient was thought to be induced by the occupational inhalation of hard metal.