Lymph nodes play an important part in the body's defense against infection. Swelling might occur even if the infection is trivial or not apparent. Swelling of lymph nodes generally results from localized or systemic infection, abscess formation, or malignancy.
Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.