Hi msjc Tubercular infection do not lead to life long immunity. you may have the disease again after being declared cure which can be re-activation of dormant bacilli or re-infection from community. TB usually heals by fibrosis...so you may have scars or fibrosis after treatment and commonest site is upper lobe but this is not a sign of active infection.... lymph node enlargement can be due to infection including TB, malignancy, sarcidosis, etc.....It is better to go for a simple test called FNAC at pathology centre and the report will tell the cause of lymph node enlargement... better meet your doctor for the same.... best wishes