Recently we have been seeing two young patients. They should have had a CT scan of the chest for other reasons, but 3mm-6mm pulmonary nodules (which we call microscopic pulmonary nodules) were found in the lungs. For lung nodules found for the first time, especially lesions smaller than 10mm, a regular follow-up approach is usually taken. However, these two cases are somewhat unique in that there is a difference in the imaging presentation. The former was chosen between the option of aggressive surgery and conservative observation. Intraoperative rapid pathology confirmed “carcinoma in situ”, and in addition to local excision, the lymph nodes with potential metastasis were removed. One case was reported as “microinvasive adenocarcinoma” after surgery. Therefore, lung nodules should be taken seriously, although they are not the same as lung cancer. Pulmonary nodules are usually round or irregular shaped lesions ≤3 cm in diameter detected on imaging (X-ray or CT). The round-like lesions ≤2 cm in diameter are also called small pulmonary nodules, and are divided into three categories according to the density of the nodules: pure ground glass nodules, mixed ground glass nodules, and solid nodules. Among the small lung nodules, 60%-70% are benign nodules (inflammation, local bleeding, tuberculosis, fibrosis, etc.) and 30%-40% are malignant nodules, so please do not panic when you find small lung nodules, as small lung nodules are not equal to lung cancer.