A lung nodule of 4cm is considered relatively large and is generally called a lung mass. Lung nodule refers to the imaging of a round or irregular shadow higher than the density of lung tissue, the diameter is usually less than 3cm. if the diameter is larger than 3cm, then it is called a lung mass, not a lung nodule. Lung cancer is relatively more likely, but also can be seen in tuberculosis ball, lipoma, lung misshapen tumor, etc. Further examination should be performed, such as puncture biopsy to clarify the nature of the pathology. As the lung nodule is large, it is recommended to consult a doctor as soon as possible, follow the advice of a professional doctor, further improve the examination to clarify the nature of the nodule, and if the nodule is determined to be malignant, perform surgical resection in time, so as to avoid missing the time for treatment.