<prompt> Air bronchogram on chest Xray denotesIntrapulmonary lesionExtrapulmonary lesionIntrathoracic lesionExtrathoracic lesion  <response>: A solitary pulmonary nodule SPN or coin lesion is a mass in the lung smaller than 3 centimeters in diameter.It can be an incidental finding found in up to 0.2 of chest X-rays and around 1 of CT scans. 