| Follicular hyperplasia | |
|---|---|
| Other names | Reactive follicular hyperplasia,Lymphoid nodular hyperplasia |
 | |
Follicular hyperplasia (FH) is a type oflymphoid hyperplasia and is classified as alymphadenopathy, which means a disease of the lymph nodes. It is caused by a stimulation of theB cell compartment and by abnormal cell growth of secondaryfollicles. This typically occurs in thecortex without disrupting thelymph node capsule.[1] The follicles arepathologicallypolymorphous, are often contrasting and varying in size and shape.[2] Follicular hyperplasia is distinguished fromfollicular lymphoma in itspolyclonality and lack ofbcl-2 protein expression, whereas follicular lymphoma ismonoclonal, and expressesbcl-2.[3]
Lymphadenopathies such as follicular hyperplasia can show various symptoms such as fever, chills, night sweats, unexplained weight loss and prominent localizing symptoms are non age and non-gender specific.[4]
Although humanlymph nodes cannot be seen with the naked eye,[citation needed] they are sometimes palpable by pressing against the skin to feel for swelling and pressure. Swelling of lymph nodes can range from pea sized to golf ball sized depending on the given condition. A person can have reactive lymph nodes throughout multiple areas of the body which can cause swelling, pain, warmth and tenderness.[medical citation needed]
The following are examples of potential causes for reactivelymphadenopathies, all of which have predominantlyfollicular patterns:[1]
Microorganisms can infect lymph nodes by causing pain and inflammation including redness and tenderness. Bacterial, fungal and viral infections includingBartonella,Staphylococcal,Granulomatous,Adenoviral andLyme disease are all associated with follicular hyperplasia.[6]
Otherautoimmune related diseases that are associated arerheumatoid arthritis,systemic lupus,dermatomyositis andSjögren syndrome.Immunoglobulin G- related diseases are immune-mediatedfibroinflammatory conditions that affect many organs in the body. Chronic inflammatory disorders such asKimura disease are also the outcome of inflamed or enlarged lymph nodes. Bacteria such asTreponema pallidum, or parasites such asToxoplasma gondii, can cause enlargement of the lymph nodes as well. Other related causes such aslymphoproliferative conditions known asCastleman disease, orprogressive transformation of germinal centers cause lymph node enlargement. Environmental conditions that may also play a role are animal or insect exposure, chronic medication usage andimmunization status. The patient's occupational history such as metal work or coal mining may expose them tosilicon orberyllium.[6]
Follicular hyperplasia is common in children and young adults, but is not limited to any age;it is also common among the elderly and is non-sex specific.[failed verification][1] Children often experience reactive lymph nodes when they are younger due to new exposure of environmentalpathogens, even without development of an infection.[medical citation needed] Clinically, follicular hyperplasialymphadenopathy is usually restricted to a single area on the body, but can also be on several parts of the body as well. Follicular hyperplasia is one of the most common types of lymphadenopathies and can be associated withparacortical andsinushyperplasia.[1]
The specificpathology of follicular hyperplasia has not been fully understood yet. It is known, however, that a stimulation of theB cell compartment and by abnormal cell growth of secondaryfollicles are key factors to the pathology of follicular hyperplasia. This typically occurs in thecortex without disrupting thelymph node capsule.[1] It has also been described that the condition may stem from primary reactivelymphoidproliferations that may be triggered by an unidentifiedantigens or some sort ofchronic irritation by ultimately causing lymph node enlargement.[7]
Lymph node enlargement can occur for many reasons. First of all, the lymph nodes function to act as a filter for thereticuloendothelial system. They contain multi-layeredsinus by exposingB andT celllymphocytes andmacrophages and are found within the blood. When the immune system recognizes foreign proteins in order to mount an attack, it requires help from these blood cells. During this reaction the responding cell lines become duplicated in response to a foreign attack, and therefore increase in size.Node size is considered abnormal when it exceeds 1 cm, however this differs from children to adults.[4]
Localized or specificadenopathy often occur in clusters or groups of lymph nodes that can migrate to various areas of the body. Lymph nodes are distributed within all areas of the body and when enlarged, reflect the location oflymphatic drainage. Thenode appearance can range from tender, fixed or mobile and discrete or matted together.[4] It is important to note that reactive lymph nodes are not necessarily a bad thing, in fact they are a good indication that thelymphatic system is working hard. Lymph fluids can build up in lymph nodes as a way to trap harmful bacteria and other harmful pathogens in the body to prevent it from spreading to other areas.[medical citation needed]
Substances that are present within theinterstitial fluids such asmicroorganisms,antigens or evencancer can enterlymphatic vessels by forming the lymphatic fluids. Lymph nodes help filter these fluids by removing material towards the direction of blood circulation. When antigens are presented, thelymphocytes inside of the node trigger a response which can causeproliferation or cell enlargement. This is also referred to as reactivelymphadenopathy.[8]
Follicular hyperplasia can be distinguished among other diseases by observing the density of a lymph follicle on low magnification. Lymph nodes with reactive follicles contain extensions outside its capsule, follicles present throughout the entire node, obviouscentroblasts and the absence or diminishingmantle zones.Immunohistochemistry can help distinguish a difference between a patient with follicular lymphoma to follicular hyperplasia.[1] Reactive follicular hyperplasia does not expressBCL2 proteins inB cellgerminal centers and are absent light chain reaction inimmunostaining andflow cytometry as well as absentIG rearrangements.[1]
Localized, or specificlymphadenopathies should be evaluated foretiologies that are associated with lymphatic drainage patterns. During a completelymphatic physical examination, generalized lymphadenopathy may or may not be ruled out.[6]
BCL2 protein expression is usually absent in follicular hyperplasia but prominent in follicular lymphomas. A comparison with other stains that includegerminal center markers such asBCL-6 orCD10 is useful to compare when determining a proper diagnosis.[1]CD10 positive cells aremetalloproteinase which activate or deactivate peptides throughproteolytic cleavage.[9]
An official diagnosis of follicular hyperplasia might includeimagining such as aPET scan and a tissuebiopsy, depending on the clinical location and also the location oflymphadenopathy.[6] A commonblood panel test may help rule out other possible diagnosis, such as lymphomas based on the number of red, white and platelet cells found in the blood. If the patient has low blood cell counts, this can be an indication oflymphoma. Another indication of lymphoma compared to follicular hyperplasia is high levels oflactic dehydrogenase (LDH) andC-reactive proteins (CRP).[medical citation needed] A lymph nodebiopsy may reveal an official diagnosis forlymphoma, by ruling out follicular hyperplasia which can be determined by the rate ofproliferation.[medical citation needed]
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Factors that identifyetiology of the patient include age, duration of lymphadenopathy, external exposures, associated symptoms and location on the body.[1]
| Atenolol | Hydralazine | Penicillins | Pyrimethamine (Daraprim) |
| Captopril | Allopurinol | Phenytoin (Dilantin) | Quinidine |
| Carbamazepine (Tegretol) | Primidone (Mysoline) | Trimethoprim/sulfamethoxazole |
Beta blockers such asAtenolol orACE inhibitors likeCaptopril, can cause certain lymphadenopathies for some individuals. Captopril is an analog toproline and completely inhibitsangiotensin converting enzymes (ACE) and as a result decreasesangiostatin II production. It can also inhibit tumorangiogenesis throughmatrix metallopeptidase (MMPs) andendothelial cell migration, which can ultimately cause lymph node enlargement.[10][failed verification]
Carbamazepine is ananticonvulsant that works by decreasingnerve impulses that are brought on byseizures. Some of the more serious side effects are allergic skin reactions and low blood cell counts. Otheranticonvulsant medications,Phenytoin andPrimidone, can also cause lymph node enlargement due to changes in the blood after drug administration.[medical citation needed] Other medications such asPyrimethamine,Quinidine andTrimethoprim/ sulfamethoxazoleantibiotics also change blood chemistry after administration and can cause lymph node enlargement.Hydralazine andAllopurinol are medications that are prescribed to patients to lower their blood pressure and arevasodilators causing the blood cells todilate.[citation needed]
A family history,regional exam andepidemiological cues are usually the most useful information to utilize for treatment options because it can help classify the patient's condition as either low risk, or high risk. Low risk, meaning the patient is not exposed tomalignancy or serious disease and high risk means that they are. If the patient is not at risk for malignancy or serious illness, it is recommended for the physician to observe any changes or symptom resolutions within 3–4 weeks. If the lymphadenopathy does not resolve the next step would be getting a biopsy.[4] Proceeding a tissue sample, an effective treatment for follicular hyperplasia is surgical removal of thelesion after an initial conformation of the disease based on the patients biopsy results.[7]
Typically follicular hyperplasia is categorized as abenignlymphadenopathy. This is usually almost always treatable, but only until it progresses intomalignancy.[8] Therefore, follicular hyperplasia patients tend to live a long life until their condition is either treated or goes away on its own. Follicular hyperplasia becomes problematic when left untreated by increasing the risks for developing various types of cancers.[8]
Follicular hyperplasia is one of the most common types ofbenignlymphadenopathies.[1] It can be typically found in children and young adults however all ages are subject to follicular hyperplasia, including the elderly. Lymphadenopathies such as follicular hyperplasia, are usually localized but can also be generalized and are non gender specific. Over 75% of all lymphadenopathies are observed as local, usually involving specifically the head and neck regions.[4] It has been estimated that patients who present lymphadenopathy has an estimated 1.1% chance of developing malignancy.[11]
The rate of childhoodmalignancy associated with lymphadenopathy is low, however this increases with age. A majority of reported cases in children are usually caused by infections orbenignetiologies. In one study, 628 patients underwent anodal biopsy and resulted benign or self-limited causes found in nearly 79% in patients younger than 30 years of age. This was also the case for nearly 59% of patients between the ages of 31 and 59 years old and 39% in patients that were older than 50 years of age. Lymphadenopathies that last more than 2 weeks or over one year and does not develop progression of cancer cells have a low chance ofneoplastic effects.[11]
During a recent 2019 study, a 51-year-old woman was examined by medical professionals at the department of Oral and Maxillofacial surgery, Tokyo Medical University Hospital, to treat an existing condition which was an inflamed mass of cells noted in patient's bottom left gum line. A samplebiopsy was obtained from the patient's mouth and the indicated results showedbenignlymphoid tissues. Further investigation under a microscope revealed lymphocytic tissues composed of scatteredlymphoidfollicles with obviousgerminal centers and welldifferentiatedlymphocytes surrounded by defiantmantle zones. Immunochemical staining revealed positivity for lymphoid particlesCD20 andCD79. This study was significant because they were able to diagnose a very rare case of follicular lymphoid hyperplasia derived from an unusual origin site of the mouth; however, they were unable to determine the onset of her condition. It is important to note that after the mass was removed there was no signs of recurrence after the first year of removal.[7]
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