Idiopathic Disseminated Pulmonary Ossification

Abstract

Idiopathic disseminated pulmonary calcification is an unusual condition in which metaplastic bone, occasionally containing marrow, is laid down in the inter-alveolar, interlobular, and subpleural connective tissue and alveoli of the lung. It is rarely diagnosed radiographically but is occasionally an incidental finding at autopsy. Schinz (11) and Salzman (9) each discussed and illustrated this condition, Schinz among others (3, 8, 14) dividing pulmonary ossification into granular and branched forms. The former is found in association with mitral stenosis and is well documented in the radiological literature as pulmonary ossific nodules in mitral valve disease (4–6, 15). The branched or racemose form, referred to in this article as idiopathic disseminated pulmonary ossification, differs etiologically, clinically, and radiographically from the nodular form and consists of spicules of bone arranged in a reticulated pattern, sometimes described as twig- or branch-like. It is found principally but not exclusively in the lower lobes of asymptomatic, elderly males. The case presented below, with autopsy verification, is of the latter type and is apparently the first to be described in an American radiological journal. W. S. H., a 76-year-old male, had been well until about 8:30 P.M., Dec. 6, 1967, when he suddenly became unresponsive and died just as he arrived in the Emergency Room. He did not respond to treatment. An electrocardiogram was compatible with an acute posterior infarct, but no physical examination or laboratory data were recorded. A past history of bronchiectasis, bronchitis, and chronic pneumonitis was obtained from his personal physician. The patient had experienced what appeared to be a mild myocardial infarction about one year before this final admission. A postmortem examination performed by Jon E. Boline, M.D., confirmed the diagnosis of myocardial infarction with rupture of the heart and hemopericardium. The right lung weighed 730 g and the left lung 490 g. Pleural calcification was marked on the surface of both lungs, and palpation revealed firm spicules within the lung parenchyma. Microscopic studies showed acute pulmonary edema, congestion of vessels and alveolar capillaries, bronchiectasis with dilated terminal bronchi, and chronic inflammation and fibrosis. Many areas of interstitial fibrosis were seen, primarily sub-pleural in location. Histologically, ossification was quite extensive, and some of the trabeculae had fatty marrow while others contained blood-forming marrow. The bone consisted principally of small trabeculae about 1 mm in diameter.