C.O.
My 9 year old has lymph nodes that protrude from his neck. They have been this way since he was 2 years almost 3 years old.
Our pediatrician did some blood work up and found NOTHING wrong. They said in a small number of kids, lymph nodes protrude and are just showing they are functioning.
To alleviate your fears - ask for a full blood work up and see what's going on. If he doesn't bruise easily (one of the signs of leukemia) then I would venture to guess he is like my son and the lymph nodes are working/functioning. If you don't feel comfortable with that - ask what type of specialist you need to see and their recommendation for him/her and go.