Patrick Ha, MD, FACS replies...
It sounds like he is having recurrent low grade infections of the tonsils that are causing them to 'swell.' We are usually less concerned about the threat of a malignant process such as lymphoma when they are symmetric, if they enlarge and shrink, and if he doesn't have any persistent lymph nodes elsewhere in his neck.
Ultimately, if he is on repeated courses of antibiotics, or missing school frequently, or if he is symptomatic in other ways, it may be worthwhile to discuss removal of his tonsils with your physicians. However, it doesn't sound like at this time that much further workup is required.
Patrick Ha, MD FACS
Johns Hopkins Department of Otolaryngology
Johns Hopkins Head and Neck Surgery