Editing Lymph node (section)

==Clinical significance==
===Swelling===
[[File:Swollen Lymph Nodes.jpg|thumb|200x200px|A still image from a 3D medical animation showing enlarged lymph nodes]]
{{Main|Lymphadenopathy}}
<!--Definitions, causes and symptoms-->Lymph node enlargement or swelling is known as [[lymphadenopathy]].{{sfn|Davidson's|2018|p=927}} Swelling may be due to many causes, including [[infection]]s, [[neoplasm|tumor]]s, [[autoimmune disease]], [[adverse drug reaction|drug reactions]], diseases such as [[amyloidosis]] and [[sarcoidosis]], or because of [[lymphoma]] or [[leukemia]].{{sfn|Hoffbrand's|2016|p=114}}{{sfn|Davidson's|2018|p=927}} Depending on the cause, swelling may be painful, particularly if the expansion is rapid and due to an infection or inflammation.{{sfn|Davidson's|2018|p=927}} Lymph node enlargement may be localized to an area, which might suggest a local source of infection or a tumour in that area that has spread to the lymph node.{{sfn|Davidson's|2018|p=927}} It may also be generalized, which might suggest infection, connective tissue or autoimmune disease, or a malignancy of blood cells such as a [[lymphoma]] or [[leukemia]].{{sfn|Davidson's|2018|p=927}} Rarely, depending on location, lymph node enlargement may cause problems such as difficulty breathing, or compression of a blood vessel (for example, [[superior vena cava obstruction]]{{sfn|Davidson's|2018|p=1326}}).

<!--Investigations-->Enlarged lymph nodes might be felt as part of a [[medical examination]], or found on [[medical imaging]].<ref>{{Cite journal |last1=Gaddey |first1=Heidi L. |last2=Riegel |first2=Angela M. |date=2016-12-01 |title=Unexplained Lymphadenopathy: Evaluation and Differential Diagnosis |url=https://pubmed.ncbi.nlm.nih.gov/27929264 |journal=American Family Physician |volume=94 |issue=11 |pages=896–903 |issn=1532-0650 |pmid=27929264}}</ref> Features of the [[medical history]] may point to the cause, such as the speed of onset of swelling, pain, and other [[constitutional symptoms]] such as fevers or weight loss.{{sfn|Davidson's|2018|p=913}} For example, a tumour of the breast may result in swelling of the lymph nodes under the arms{{sfn|Davidson's|2018|p=927}} and weight loss and [[night sweat]]s may suggest a malignancy such as lymphoma.{{sfn|Davidson's|2018|p=927}}

In addition to a [[medical exam]] by a [[medical practitioner]], [[medical test]]s may include [[blood test]]s and scans may be needed to further examine the cause.{{sfn|Davidson's|2018|p=927}} A [[biopsy]] of a lymph node may also be needed.{{sfn|Davidson's|2018|p=927}}

===Cancer===
[[File:Crc met to node1.jpg|thumb|200px|right|[[Micrograph]] of a [[mesenteric lymph node]] with [[adenocarcinoma]]]]
Lymph nodes can be affected by both primary [[cancer]]s of lymph tissue, and secondary cancers affecting other parts of the body. Primary cancers of lymph tissue are called lymphomas and include [[Hodgkin lymphoma]] and [[non-Hodgkin lymphoma]].{{sfn|Davidson's|2018|p=961}} Cancer of lymph nodes can cause a wide range of symptoms from painless long-term slowly growing swelling to sudden, rapid enlargement over days or weeks, with symptoms depending on the [[tumour grade|grade]] of the tumour.{{sfn|Davidson's|2018|p=961}} Most lymphomas are tumours of B-cells.{{sfn|Davidson's|2018|p=961}} Lymphoma is managed by [[Hematology|haematologists]] and [[Oncology|oncologists]].

Local cancer in many parts of the body can cause lymph nodes to enlarge because of tumorous cells that have [[metastasis]]ed into the node.{{sfn|Davidson's|2018|p=1324}} Lymph node involvement is often a key part in the diagnosis and treatment of cancer, acting as "[[Sentinel lymph node|sentinels]]" of local disease, incorporated into [[TNM staging]] and other [[cancer staging]] systems. As part of the investigations or [[Medical diagnosis#Other diagnostic procedure methods|workup]] for cancer, lymph nodes may be imaged or even surgically removed. If removed, the lymph node will be stained and examined under a microscope by a [[Pathology|pathologist]] to determine if there is evidence of cells that appear cancerous (i.e. have metastasized into the node). The staging of the cancer, and therefore the treatment approach and prognosis, is predicated on the presence of node metastases.

===Lymphedema===
[[Lymphedema]] is the condition of swelling ([[edema]]) of tissue relating to insufficient clearance by the lymphatic system.<ref name="Maclellan2014">{{cite journal | vauthors = Maclellan RA, Greene AK | title = Lymphedema | journal = Seminars in Pediatric Surgery | volume = 23 | issue = 4 | pages = 191–7 | date = August 2014 | pmid = 25241097 | doi = 10.1053/j.sempedsurg.2014.07.004 }}</ref> It can be congenital as a result usually of undeveloped or absent lymph nodes, and is known as primary lymphedema. Lymphedema most commonly arises in the arms or legs, but can also occur in the chest wall, genitals, neck, and abdomen.<ref name=":lymph node cancer">{{Cite web |url=https://www.mayoclinic.org/diseases-conditions/lymphedema/symptoms-causes/syc-20374682|title = Lymphedema|date=2019-09-18|website=MayoClinic.org|language=en-US|access-date=2022-11-17}}</ref> Secondary lymphedema usually results from the removal of lymph nodes during [[mastectomy|breast cancer surgery]] or from other damaging treatments such as [[radiation therapy|radiation]]. It can also be caused by some parasitic infections. Affected tissues are at a great risk of infection.{{citation needed|date=November 2019}} Management of lymphedema may include advice to lose weight, exercise, keep the affected limb moist, and compress the affected area.<ref name=Maclellan2014/> Sometimes surgical management is also considered.<ref name=Maclellan2014/>