Lung nodules 4mm is not normal, but the specific severity is mainly related to the nature of the nodules, nodules have benign and malignant, benign belongs to the non-serious situation, while malignant is a more serious situation. 1. Not serious situation: lung nodules 4mm benign will not occur far spread, will not endanger life and health, do not need to accept special treatment. It is recommended that every six months or so, go to the hospital to review the chest ct, to determine whether the nodule has changed. 2. serious situation: lung nodule 4mm is malignant, need surgical treatment, after thorough surgical treatment, most can be cured, malignant nodules have a great harm to the body, also does not exclude the occurrence of metastasis. After surgery, we should pay attention to the wound cleaning, avoid pollution, rest, quit smoking and drinking, eat less spicy and stimulating food, eat more fruits and vegetables. Small nodules in the lungs 4mm should promptly seek medical attention, confirmed by the doctor and then do further treatment.