A 4mm lung nodule that has remained unchanged for three years usually does not require treatment, and regular follow-up chest CT examinations are usually all that is needed to closely monitor changes in the lung nodule.
A 4mm lung nodule is generally more likely to be benign, and the fact that it has been three years since the nodule changed further indicates that the lung nodule is very likely to be benign.
Moreover, benign nodules that occur in the lungs usually grow slowly, and 4mm nodules seldom have clinical symptoms, so the overall impact on the patient is relatively small, so there is generally no need to take treatment measures.
However, benign nodules in the lungs also have a certain risk of becoming cancerous. Although treatment is not necessary, regular follow-ups should be conducted to observe the changes of the nodules, and it is generally recommended that the patients visit the hospitals regularly and be followed up by the specialized doctors for observation.