Lymphoid hyperplasia is an increase in the number of normal cells (called lymphocytes) that are contained in lymph nodes. This most often happens when there is an infection with bacteria, viruses, or other types of germs and is part of the body's reaction to the infection.
Ball JW, Dains JE, Flynn JA, Solomon BS, Stewart RW. Lymphatic system. In: Ball JW, Dains JE, Flynn JA, Solomon BS, Stewart RW, eds. Seidel's Guide to Physical Examination. 9th ed. St Louis, MO: Elsevier; 2019:chap 10.