5mm lung nodule is generally has been long how long, there is no way to clarify, the formation of lung nodule causes inflammation mechanization, tuberculosis, tumors, etc., according to the formation of different causes of different length of time will also be different. 1. Inflammation: inflammation of the lungs if the patient has not been treated or treatment is not formal, may lead to the disease is not cured, repeated inflammation of the lungs and damage repair will gradually form nodules in the lungs, this time the formation of the time is generally 1 ~ 2 months. 2. Tuberculosis: if the patient is infected with Mycobacterium tuberculosis and tuberculosis occurs, it will cause autoimmune reaction of the body and form tuberculosis nodule which is a combination of inflammatory secretion, Mycobacterium tuberculosis and local necrotic tissues, and the formation of nodule can be for three months, half a year and above. 3. Tumor: if patients form nodules in the lungs due to lung tumors, the time of nodule formation should be considered according to the pathological typing of the cancer and the patient’s autoimmune factors. If the patient has been exposed to a polluted environment for a long time, the time of nodule formation may be about 3 months; if the patient has been smoking for a long time leading to lung cancer, the time of nodule formation may be decades. If a patient finds a 5mm lung nodule, he or she should go to the hospital immediately for examination to determine the nature of the nodule and then undergo standardized treatment.