Abstract: Objective To describe the etiology and computed tomography（CT） characteristics of pulmonary nodules and lung masses in order to provide a basis for differentiating benign and malignant masses. Methods CT chest scans were performed on 646 patients from five research centers in Qingdao；patients had been diagnosed with benign or malignant masses based on pathology.Scans for the two types of masses were compared using statistical analysis. Results CT scans for benign and malignant masses differed significantly in sentus，pleural indentation and air bronchogram results. Conclusion Spiculation and pleural indentation on CT scans suggest that the lung mass or pulmonary nodule may be malignant，while air bronchogram suggests it may be benign.

Key words: Pulmonary neoplasms, Imaging characteristic, Nodule, Eitology