Metaplasia of bone in lungs and bronchi: report of 2 cases.

Two cases are reported of pulmonary osseous metaplasia in elderly men aged 91 and 64 years. The first case represented disseminated metaplastic bones occurring throughout the lungs. In the second instance, small foci of metaplastic bones were localized in some bronchial walls of the upper lobe of the right lung which had old treated tuberculosis, severe fibrosis, and bronchiectasis. Both cases also had advanced pulmonary emphysema and interstitial fibrosis. It is suggested that fibrosed interstitium of the lungs and bronchial walls has turned into bony metaplasia in both patients. However, osseous metaplasia from cartilage of the bronchial walls is additionally suggested in case 2. Multiple factors probably play roles in development of bony metaplasia.