I often hear patients ask the question: Is this lung nodule malignant? Dr. Zhang, tell us how to see if a nodule on CT is a malignant tumor or lung cancer? First of all, the main difference between malignant tumor and benign tumor is that the cells of malignant tumor grow fast. Malignant tumor is like a weed, its growth is not controlled by the normal organism and it may metastasize, so thin layer CT with 3D reconstruction and regular dynamic CT observation help to identify benign and malignant. During the follow-up, if the lesion disappears or shrinks significantly, inflammatory reaction may be considered; if it remains the same or does not increase at all, it may be benign; if, during the follow-up, the nodule or mass increases, or the density of the lesion becomes solid, or if there are signs of blood vessel growth or angiogenesis seen on CT, it suggests a high possibility of malignancy. Secondly, burr-like nodules or root-like changes indicate the possibility of nodules growing in the periphery. The appearance of small burr-like spines radiating in the periphery or growing in the periphery like the usual tree roots indicate the possibility of malignancy of the mass. Secondly, vacuole-like lesions indicate that the cells of the mass are growing too fast for blood flow to keep up, and there is no blood supply in the center of the mass, so necrosis has occurred, which appears as vacuoles on CT. Third, pleural depression, the cell growth of the mass may be relatively rapid, affecting the surrounding pleura. Fourth, bronchial inflation sign, the mass cells are growing fast, along the periphery of the bronchus. Fifthly, the egg-shaped, the middle white component may appear malignant and grow rapidly, causing the peripheral gray component to appear similar to the shape of an egg.