Pulmonary lesions described as coin lesions because of their roentgenographic appearance were studied in 95 patients. The study was limited to solitary lesions, homogeneous or calcified, 1.0 to 4.5 cm. in size, round or oval in shape, with sharp borders surrounded by normal lung, found during the examination of asymptomatic patients. The final diagnosis was based on histological examination. This showed the lesion to be malignant in 6 cases. In 55 cases it was a fibrocaseous granuloma, and in 14 it was a tuberculoma. The size of the lesion was not significant. Calcification in a solitary pulmonary nodule is a good but not an absolute sign that it is benign. The authors believe that solitary pulmonary lesions, with few exceptions, should be excised and examined histologically.
Pischnotte WO, Sammons BP. SOLITARY COIN LESIONS OF THE LUNG. JAMA. 1960;173(14):1532-1535. doi:10.1001/jama.1960.03020320012004