The solitary circumscribed pulmonary nodule; study of seven hundred five cases encountered roentgenologically in a period of three and one-half years.

The histories of 705 patients with solitary circumscribed pulmonary masses have been analyzed. In 294 instances the masses appeared roentgenographically to be calcified, and in their subsequent course none of these gave any evidence of malignancy. In 103 instances the masses accompanied a known extrapulmonary malignant neoplasm, and at least 86 of these proved to be metastatic. In 37 instances nodules were known to have been stable as to size for two years or more, but evidence as to their nature was incomplete. It is advisable to keep both calcified and stable nodules under observation, but the possibility that a malignant lesion is present is greater in the stable, noncalcified than in the calcified masses.