Lymph nodes are bean-shaped organs found throughout the body that filter lymph and house immune cells. A lymph node contains a fibrous capsule enclosing compartments of connective tissue and lymphocytes. The parenchyma is divided into an outer cortex and inner medulla. A normal lymph node contains mature lymphocytes, plasma cells, centrocytes, centroblasts, and immunoblasts. Lymphadenopathy refers to enlarged lymph nodes, which can be caused by infection, inflammation, autoimmune disease, or cancer metastasis. Physical examination of lymph nodes considers location, number, size, consistency, tenderness, and mobility to evaluate causes of lymphadenopathy.