Hello -
If your son was seen by a hematologist who found nothing underlying the high WBC and swollen glands, and your son has improved and not been sick since, all is probably well. A
lymph gland can take a good long time to return to normal size and, sometimes, there is a permanent difference between one and the complimentary one. Still, it can't hurt to mention this to the doctor. It would seem a comprehensive workup was done and your son was followed and nothing ever showed up. For your own peace of mind, though, at least a call in to ask about the one still-enlarged gland might be helpful.
Hoping all is well. Please stay in touch with us here.