Hi. Thanks for your query. Noted the history of presence of old and new lymph nodes in the mesentery of jejunum, like to be non-specific, wants to know the cause, whether bad, meaning of reactive and so on. ....... Reactive means when the lymph node enlarge for no obvious reasons like cancer or tuberculosis. This also means they they can enlarge due to infection of any sort or allergy. The commonest cause is an infection in the jejunum, may be it is loaded with worms or so. I would advise you the following: A course of an antibiotic and anti-inflammatory medication. Medicines for worm infestation. Review the progress with high resolution Ultrasonography. If no response, laparoscopy and lymph node biopsy to find the cause and get treated accordingly. This can be due to tuberculosis.