Chronic inflammation can be manifested by enlarged nodes with mononuclear cell infiltration. The nodes may become fluctuant if invaded by bacteria. If capsular distension is marked, tenderness may be present. The cells lining the sinuses become hypertrophied and often undergo hyperplasia.Īcutely inflamed nodes become enlarged because of cellular infiltration and edema. With less severe reactions, there is a neutrophilic infiltrate about the follicles, and numerous neutrophils can be found within the lymphoid sinuses. When bacteria are the cause of the reaction, the centers of the follicles may undergo necrosis with suppuration. Histologically, lymphoid follicles are prominent, with large germinal centers containing numerous mitotic figures. Macroscopically, the nodes of acute nonspecific lymphadenitis become swollen, gray-red, and engorged. Lymph nodes enlarge because of lymphocyte proliferation or macrophage hyperplasia resulting from infiltration of microorganisms or malignant cells, antigenic interaction, or neoplastic proliferation of lymphocytes or phagocytes. Generalized lymphadenopathy and reticuloendothelial system hyperplasia can occur secondary to widespread sepsis. If this barrier of host resistance is overcome, the infectious process may spread to more distant nodes or to the blood stream. When a local infection occurs, the regional lymph nodes react to the invading microorganisms. However, they are involved in virtually all infectious processes. With the exception of neoplasia, lymph nodes are rarely the site of primary disease. The lymph nodes participate in the filtration of microorganisms, the production of antibody, and the processing of lymphocytes within the human body. When an infection is present, germinal centers form and the node begins to release lymphocytes. Fibrous septa or trabeculae extend from the covering capsule toward the center of the node.
Lymph moves into a node via different lymphatic vessels and emerges by one or two efferent vessels. Each lymph node is enclosed by a fibrous capsule. Lymph nodes are oval bean-shaped structures. Lymphangitis is defined as an inflammation of lymphatic channels, usually in the subcutaneous tissues. Lymphadenitis is defined as an acute or chronic inflammation of lymph nodes. Normal nodes are usually less than 1.0 cm in diameter and tend to decrease or remain stable in size. The body has approximately 600 lymph nodes, but only those in the submandibular, axillary or inguinal regions are normally palpable in healthy individuals. Lymphadenopathy is an acute or chronic abnormal state of either size or consistency of the lymph nodes it is a response to infection, inflammation, or malignancy.
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