What is lymphoid hyperplasia?

Lymphoid hyperplasia is the swelling of lymphatic tissue due to an accelerated increase in lymphocytes when the immune system perceives a threat to the body. Lymphoid hyperplasia, or lymphoid hypertrophy, can occur in the presence of bacteria, viruses, or abnormal tissue growth. The increase in the number of lymphocytes, commonly associated with the body's immune response, can be initiated by a local or systemic infection. Doctors refer to lymphoid hyperplasia as benign, reactive, or a combination of the two.

Lymphocytes, or B cells, are white blood cells that originate in the bone marrow and travel through the blood and lymphatic systems. An immune response is triggered when the body detects an invasion, and lymphocytes try to prevent the foreign invader from traveling throughout the circulatory system. Part of the immune system, also known as the reticuloendothelial system, consists of the lymph glands. As blood passes through the lymphatic system, it is constantly checked by lymphocytes. Depending on the type of pathogen, lymphocytes either develop antibodies against that substance or gobble up the threat in a process known as phagocytosis.

Lymphocyte populations locally, or throughout the system, begin to increase as part of the normal defense response. New lymphocytes are generally not released to travel through the system until they have reached maturity. When proliferation occurs in a particular area, the lymph glands begin to swell. Localized infections in the upper respiratory system, for example, commonly cause inflammation of the parotid gland in the neck. The proliferation and swelling continue until the infection resolves naturally or is treated with medication.

Appendicitis is another example of localized lymphoid hyperplasia. The condition usually begins when a blockage occurs between the appendix and the part of the intestine known as the cecum. The blockage can be caused by trapped stool, excess mucus, or lymphatic swelling. After the blockage, bacteria that normally circulate through the intestine can invade the wall of the appendix and trigger the immune system. Swelling, inflammation, and discomfort are signs that the immune system has launched a response.

Castleman's disease is a rare disorder that usually results in benign growths in one location or all over the body. These growths can appear on the neck, chest, stomach, or intestinal regions. Lymphoid hyperplasia usually occurs when lymphocytes try to fight off the invasion of foreign tissue. Patients who have this disease usually experience fever, weight loss, and skin rashes along with anemia caused by the destruction of red blood cells. A chemical response usually includes an increase in gamma globulin, as well as enlargement of the liver and spleen due to increased lymphocyte populations.

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