Lung nodule 2.5cm does not necessarily belong to early lung cancer. Lung nodules can be caused by proliferative lesions and solid lesions in the lung. 1. Proliferative lesion: it is chronic inflammation of lungs forming granulation of granulation tissue in lung tissue, which can be seen in chronic pneumonia, inflammatory pseudotumor, tuberculosis, pneumoconiosis and other diseases, and the imaging manifests as nodular and flaky high-density shadows with clear edges. 2. Solid changes in the lungs: the gas in the lungs is replaced by pathological tissues such as inflammation, edema, hemorrhage, etc., which produces a high-density shadow. It can be seen in lung cancer, pneumonia, tuberculosis, pulmonary edema, pulmonary embolism and so on. Imaging characteristics show that the density of the lesion is uniformly elevated, and the morphology of the lesion is mostly irregular, which can be fused into a piece, and can be manifested as ground-glass nodules and ground-glass shadows. Lung nodule 2.5 cm can be caused by many diseases, not necessarily early lung cancer. One should go to the hospital in time for examination to clarify the cause of the disease.