Most swollen lymph nodes in the neck, armpit or groin come from a simple infection and go down on their own within a few weeks; of every 100 people who see their family doctor with an unexplained swollen node, only about 1 has cancer [1, 2]. A node is more worrying if it has lasted more than 4 weeks or keeps growing, is hard, fixed or larger than 1.5 cm, sits above the collarbone, or comes with fever, night sweats or weight loss [1, 3]. Show such a node to a doctor; if no cause is found, the reliable answer is a biopsy, not course after course of antibiotics [3].
Key points
- Swollen lymph nodes are very common and usually mean the body is fighting an infection; at any one time, about half of healthy children have nodes that can be felt [1].
- The chance of cancer rises with age: in a study of family-practice patients with unexplained swollen nodes, about 4 in every 100 people over 40 had cancer, and fewer than 1 in 100 younger people [1, 2].
- A node above the collarbone should always be checked; in studies, between a third and a half of these nodes had a malignant cause [1, 2].
- Feeling a node cannot prove or rule out cancer [1]. Ultrasound helps, a biopsy gives the definite answer, and antibiotics are needed only when there are signs of a bacterial infection [3, 4].
What are lymph nodes and why do they swell?
Lymph nodes (often called glands) are small bean-like structures in the neck, armpits and groin and inside the chest and abdomen, and they are part of the immune system. When germs enter the body, immune cells gather in the nearby node, which becomes larger and sometimes painful; this is called a "reactive" node [1, 4]. That is why after a cold, a sore throat, a tooth infection or a cut on the hand, the node near that area swells and then shrinks as the infection clears [1].
A lymph node is usually considered abnormal when it is larger than about 1 cm or firmer than usual; in the groin, nodes up to 2 cm are found in many healthy adults [1]. A node that has swollen for no clear reason and does not go down may have another cause: a longer-lasting infection such as tuberculosis, an autoimmune disease, or sometimes cancer. Cancer either starts in the node itself (lymphoma) or has spread to it from somewhere else [1]. Read more about how cancer spreads: What is metastasis?
Where is the swollen node? Neck, armpit, groin and above the collarbone
| Where | Common causes | When it needs checking |
|---|---|---|
| Neck | Viral throat and mouth infections, tooth infections, glandular fever (mononucleosis), tuberculosis [1, 3] | An adult whose neck lump has persisted for 2 weeks or more without going down and without an obvious infection, or whose lump is hard, fixed or larger than 1.5 cm [3]; head and neck cancers, thyroid cancer and lymphoma are among the serious causes [1, 3] |
| Above the collarbone | Less often a simple cause than elsewhere [1] | Any node that can be felt here is abnormal and should be checked soon; cancers inside the abdomen sometimes spread to these nodes [1] |
| Armpit | A cut or infection of the hand or arm, a cat scratch, a vaccine given in the arm [1, 7] | A node with no clear cause, or one that has lasted more than 4 weeks; breast cancer and other cancers such as skin cancer are among the serious causes [1, 6] |
| Groin | Cuts and infections of the leg or foot, sexually transmitted infections; nodes up to 2 cm are found in many healthy adults [1] | A node that keeps growing or is hard and fixed; melanoma, cancer of the penis or vulva, and occasionally lymphoma are among the serious causes [1] |
| Several areas at once | Viral infections such as glandular fever and HIV, autoimmune diseases [1] | Always needs blood tests and a full examination; lymphoma is also one of the causes [1, 9] |
This table does not replace an examination by a doctor; in all of these areas most swollen nodes have a benign cause.
Swollen lymph nodes and cancer: the signs to take seriously
How long
Size and feel
Where
A node above the collarbone, or nodes that have swollen in several parts of the body at once [1].
Other symptoms
Unexplained fever, heavy night sweats, unexplained weight loss, severe tiredness or itchy skin [1, 9]. Read more: night sweats, fever and itching and unexplained weight loss.
What does a lump in the armpit mean? A painless armpit lump
Most swollen armpit nodes have a simple cause: a cut or infection of the hand or arm, a cat scratch, or a vaccine given in the arm [1, 7]. In a review of studies, armpit swelling after a COVID-19 vaccine usually appeared about a week after the injection, and in one study it went away within 4 to 5 weeks [7]. If you have had a vaccine recently, tell your doctor before a mammogram or ultrasound [7].
In women, and sometimes in men, a lump or thickening in the armpit can be a sign of breast cancer [6]. Other cancers, such as skin and lung cancer, can spread to the armpit nodes, and lymphoma can also start in them [1, 9].
Being painless does not on its own mean cancer, and pain does not rule cancer out. A painful node is more often due to inflammation and infection, but a painless, hard node that does not go away is more worrying [1]. An armpit lump with no clear cause, one that has lasted more than 4 weeks, or one that comes with a change in the breast should be examined [1, 6]. If you can also feel a lump in your breast, read: I have found a breast lump; what should I do? and symptoms of breast cancer.
Swollen neck glands in children: when to worry
Swollen neck glands are very common in children: at any one time about half of healthy children have nodes that can be felt, and the most common cause is a viral infection [1]. In a review of studies of children whose neck nodes were investigated in hospital, most nodes had a benign cause and fewer than 1 child in 20 had cancer; the most common cancer in these children was lymphoma [5].
These signs in a child need an earlier examination [1, 5]:
- a node that grows during follow-up
- a hard, rubbery, fixed node that does not move under your fingers
- several painless nodes on both sides of the neck
- a node above the collarbone
- a node with weight loss or night sweats
For children up to 14, ultrasound is usually the first scan [1]. Read about other signs in warning signs of cancer in children.
What does "reactive lymph node" mean? Terms in ultrasound and CT reports
| Term in the report | What it means |
|---|---|
| Reactive lymph node | A node that has enlarged in response to infection or inflammation; it is usually benign and shrinks once the cause settles [1, 4] |
| Oval | A normal or reactive node is usually elongated: its width is less than half its length [4] |
| Preserved fatty hilum | The bright central part of the node seen in most normal nodes; a reassuring sign [4] |
| Round, with no hilum | Among the signs that make cancer or lymphoma more likely, and it usually leads to a biopsy [4] |
| Necrosis, calcification, matted nodes | Loss of tissue inside the node, calcium deposits, or several nodes stuck together; seen both in cancer and in tuberculosis, and needs checking [4] |
| Peripheral blood flow on Doppler | Blood vessels at the edge of the node rather than in its centre; more common in malignant nodes [4] |
| Short axis less than 10 mm | On a CT scan, a node whose shorter diameter is less than 1 cm is considered normal in size [8] |
| Lymphadenopathy | Simply means a swollen or abnormal lymph node; it is not a diagnosis in itself and its cause needs to be found [1] |
Always go through the report with your doctor; no single term proves or rules out cancer.
What tests will the doctor do?
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History and examination
The doctor asks how long the node has been there, whether there has been an infection, a cut or a vaccine, and whether you have fever, night sweats or weight loss. They examine all the lymph node areas, the liver and the spleen; if the node is in the neck, they also look in the mouth, throat and voice box, or refer you to an ear, nose and throat specialist [1, 3].
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Blood tests
Such as a full blood count (CBC) and tests for infections such as glandular fever and HIV, especially when nodes are swollen in several areas [1].
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Biopsy
If the node looks suspicious or no cause is found, a sample is taken with a fine needle; this method is accurate and usually avoids surgery [1, 3]. To diagnose lymphoma, the whole node or a piece of it is usually removed, through a small operation or with a thicker (core) needle [9]. Worried about it? Read: Can a biopsy spread cancer?
When should I contact a doctor?
Most swollen nodes are harmless. But in these cases do not wait; see a doctor within the next few days:
- a node that has lasted more than 4 weeks or keeps growing [1]; in adults, a neck lump that has lasted 2 weeks or more without an obvious infection [3]
- a node above the collarbone [1]
- a node that is hard, fixed or larger than 1.5 cm, or has broken skin over it [3]
- a node with unexplained fever, heavy night sweats or unexplained weight loss [1, 9]
- nodes in several parts of the body at once [1]
- an armpit lump together with a lump or change in the breast [6]
Until the cause is known, do not take steroids (such as dexamethasone or prednisolone) on your own; they can mask lymphoma or leukaemia and delay the diagnosis [1].
Shortness of breath, difficulty swallowing, sudden swelling of the face and neck, or a red, hot, very painful node with a high fever need urgent care; if severe, call your local emergency number.
Frequently asked questions
Are swollen lymph nodes dangerous? Can they be cancer?
Usually not. A swollen lymph node is most often a sign of infection and goes down on its own. Of every 100 people who see their family doctor with an unexplained swollen node, about 1 has cancer [1, 2]. Take a node seriously if it does not go away or keeps growing; see the section "When should I contact a doctor?".
What does a cancerous lymph node feel like? Hard or soft?
A node caused by cancer is often hard, irregular and painless and stuck to the tissue underneath; a lymphoma node more often feels rubbery [1, 5]. But an infected node can also become firm, and a cancerous node is sometimes painful; that is why feeling it cannot give a certain answer, and the diagnosis is made with a biopsy [1].
I have a painless lump in my armpit; should I worry?
Being painless does not on its own mean cancer. If there is a simple cause, such as a cut on the hand, an infection or a recent vaccine, it usually goes down within a few weeks [1, 7]. If the cause is unclear, it has lasted more than 4 weeks, it keeps growing or it comes with a change in the breast, see a doctor [1, 6].
I have had a swollen lymph node in my neck for months; is that normal?
A node that has lasted more than 4 weeks should be examined at least once [1]. A node that has stayed exactly the same for more than a year is less likely to be cancer, but some slow-growing lymphomas are an exception [1]. In adults, a persistent neck lump without an infectious cause should be assessed by a specialist [3]. If it comes with a mouth ulcer or a hoarse voice, also see symptoms of mouth cancer, and if it is at the front of the neck, symptoms of thyroid cancer.
My CT scan shows enlarged lymph nodes in the abdomen; what does it mean?
On a CT scan, a node whose shorter diameter is less than 1 cm is considered normal in size [8]. Larger nodes in the abdomen may be due to infection or inflammation, but lymphoma and the spread of other cancers to the nodes are also possible causes [1, 9]. Depending on the size, the shape and your symptoms, your doctor decides whether follow-up is enough or more tests and a biopsy are needed. Read more: What is a PET scan?
Should I take antibiotics to make the node go down?
Only if the doctor sees signs of a bacterial infection, such as a red, hot, painful node with fever or a sore throat with pus [1, 3]. A guideline from the American Academy of Otolaryngology–Head and Neck Surgery Foundation advises against antibiotics for a neck lump in adults when there are no signs of bacterial infection, so that the diagnosis is not needlessly delayed [3]. If the node has not gone down after antibiotics, go back to your doctor; when the cause of a node remains unclear, the next step is a biopsy, not another course of antibiotics [1].
Assessing unexplained lymphadenopathy: criteria and numbers (for doctors)
For physicians
Pre-test probability. The annual incidence of unexplained lymphadenopathy in primary care is 0.6%, and 1.1% of cases are malignant: 4% in patients aged 40 and over versus 0.4% under 40 [1]. In the Dutch study by Fijten and Blijham (82 biopsied patients, 29 malignant), the probability of malignancy was 1.1% before referral and 11% after referral; supraclavicular lymphadenopathy was malignant in 50%, and family physicians referred 80 to 90% of malignant cases within 4 weeks [2]. In reviews, 34 to 50% of supraclavicular lymphadenopathy has been malignant [1].
Size and duration. Nodes larger than 1 cm are abnormal; palpable supraclavicular, popliteal and iliac nodes and epitrochlear nodes larger than 5 mm are abnormal, and inguinal nodes up to 2 cm are present in many healthy adults. Lymphadenopathy lasting less than 2 weeks, or more than 12 months without a change in size, has a low likelihood of being neoplastic (low-grade lymphomas excepted). Localised lymphadenopathy with a low likelihood of malignancy can be observed for 4 weeks; generalised lymphadenopathy (more than two non-contiguous groups) needs routine laboratory tests and testing for autoimmune and infectious causes (in the article's algorithm: CBC, ANA, HBsAg, HIV, RPR and PPD as clinically indicated) [1].
Neck mass in adults (AAO-HNSF guideline 2017). The risk of malignancy is increased if there is no history of an infectious cause and the mass has been present for 2 weeks or more without significant fluctuation, or its duration is uncertain, or if any of these findings is present: fixation to adjacent tissues, firm consistency, size over 1.5 cm, ulceration of the overlying skin. In these patients: CT (or MRI) of the neck with contrast (strong recommendation), a targeted examination of the mucosa of the larynx, base of tongue and pharynx, FNA instead of open biopsy, continued evaluation of a cystic mass until a diagnosis is reached (do not assume it is benign), and examination of the upper aerodigestive tract under anaesthesia before open biopsy if FNA and imaging are not diagnostic. Routine antibiotics without signs of bacterial infection are not recommended [3].
Imaging and biopsy. The ACR recommends ultrasound as the first imaging test for cervical lymphadenopathy up to the age of 14 and CT over 14. FNA has a diagnostic accuracy approaching 90% (sensitivity 85 to 95%, specificity 98 to 100%) and is a useful tool for separating reactive from malignant lymphadenopathy. Corticosteroids before a tissue diagnosis may mask leukaemia or lymphoma [1]. On ultrasound, benign or reactive nodes are oval (short-to-long axis ratio below 0.5) with an echogenic hilum and hilar or no vascularity; metastatic nodes are round (ratio above 0.5), without a hilum, with peripheral or mixed vascularity, necrosis or calcification; lymphomatous nodes are round, hypoechoic, usually without a hilum, with a micronodular pattern and often both hilar and peripheral vessels [4]. On CT (RECIST 1.1), a node with a short axis of 15 mm or more is pathological and measurable, 10 to less than 15 mm pathological but non-measurable, and less than 10 mm non-pathological [8].
Children and vaccines. In a systematic review of 2687 children with cervical lymphadenopathy (mainly referred or FNA-sampled populations), the cause was non-specific benign in 67.8%, EBV in 8.86%, malignancy in 4.69% (95% CI 3.92 to 5.52) and granulomatous disease in 4.06% (tuberculosis in 73.4% of these); non-Hodgkin lymphoma made up 46% of the malignancies [5]. Clinically detectable lymphadenopathy after COVID-19 vaccination was reported in 91 of 22,532 people (0.4%); the mean size of axillary lymphadenopathy was 18.2 mm, the mean time to onset 6.9 days (range 2 to 18 days), and in one study of 119 patients it resolved within 4 to 5 weeks [7]. Referral criteria for lymphoma and its diagnostic pathway are on the page symptoms of lymphoma.
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