Would a ct scan of a neck lymph node determine whether further tests are needed or not? can it tell if the cause is of benign nature?

Maybe: There are lymph nodes that are clearly normal on ct, some which are clearly abnormal, and an entire spectrum in between. If it is not clear, usually a follow up study is recommended as lymph nodes which are abnormal because of infection typically shrink after some time.

Perhaps: If the enlarged lymph node is associated with infection, consider waiting a couple of weeks to see if it resolves. The ct scan may be useful in determining if other lymph nodes are enlarged. Sometimes the ct scan can confirm a benign appearance in an otherwise abnormally enlarged lymph node. However, enlarged nodes may need biopsy. Please keep seeing your healthcare provider for this problem.