Circumscribed solitary pulmonary nodule is often founded on the plain chest P-A. Even if many study results of coin lesion have been reported by some scholars, it is still very difficult to judge whether the coin lesion is to be benign or malignant. In order to avoid unnecessary surgical treatment, it must be made an examination and analysis very carefully in advance. In the chest P-A, we can grasp the aspects of the site and size of lesion, marginal state of lesion, calcification, cavity, and the growth rate in comparison to follow-up chest P-A. On the basis of above-mentioned analysis, we have to judge whether it is benign or malignant, and decide the next examinations. And then the doctor make diagnosis definitely by the clinical history, plain chest P-A, tomography, bronchography, CT, variable laboratory findings.