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.
Review Date 2/22/2018
Updated by: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.