Causes of Swollen Armpit Lymph Nodes

Lymph nodes of the armpit are known as the axillary lymph nodes. They are usually not palpable (felt by touch) but may sometimes become swollen, hard and/or painful. This can arise from a host of possible causes ranging from minor injuries to infections and even cancer. Apart from the armpit itself, disorders or diseases of surrounding organs may also cause axillary lymph node swelling.

Anatomy of the Axilla (Armpit)

Lymph nodes are small, round or oval glands that are found all over the body and form part of the lymphatic system,. They are an integral part of the immune system. It helps the body to fight against infections while removing interstitial (tissue) fluid and returning it to the blood stream. The lymph nodes act as filters to trap and destroy bacteria, viruses and other harmful substances that enter the body.

Normally the lymph nodes are not palpable but may enlarge as a result of some disorder or disease. The lymph nodes of the axilla (armpit), inguinal region (groin), and neck tend to enlarge more frequently than other areas. Localized lymphadenopathy, where the lymph nodes of a single area are affected, may also be accompanied by lymph node swelling elsewhere. If this occurs, then it is considered as generalized lymphadenopathy and the cause of the swelling may likely be a systemic factor.

The central area of the armpit is surrounded by four walls :

  • an outer (lateral) wall formed by the arm.
  • inner (medial) wall formed by the chest (thorax).
  • front (anterior) wall made up by the pectoralis major muscle.
  • back (posterior) wall made up by the subscapularis, teres major and latissimus dorsi muscle

There are five groups of lymph nodes in the axilla associated with each area – the central, lateral, medial, anterior and posterior groups of lymph nodes.

Hard, Firm or Painful Lymph Nodes

Lymph nodes that are swollen due to infections tend to be firm and painful. Enlarged lymph nodes due to cancer are usually firm or hard in consistency, fixed (not freely mobile), usually not painful, and may be matted (stuck to each other). They may also increase in size over time.

In some cases the lymph nodes may be felt, without the presence of any disease, but are usually small (less than 1 cm in size), soft and painless lumps.

Cysts and abscesses under the skin in the armpit may produce lumps which could be mistaken for enlarged lymph nodes.

Causes of Enlarged Axillary (Armpit) Lymph Nodes

Local Causes

One or more lymph nodes in one or both axilla (armpit) may become swollen commonly due to :

  • Injury to the armpit, arm or hand.
  • Localized infection in the armpit or of the arm, hand or breast, which drains into the axillary lymph nodes.
  • Cat scratch disease is an illness which is caused by the scratch or bite of an infected cat. Cats act as carriers of the bacterium Bartonella henselae which causes cat scratch disease although cats do not suffer from the disease themselves. There may be generalized symptoms of fever, headache, loss of appetite and fatigue along with lymph node swellings, especially of the head, neck and axilla. Cat scratch disease normally resolves on its own without any specific treatment. However the infection may be more debilitating in persons who are immunocompromised like in  HIV/AIDS patients or those on chemotherapy for cancer.
  • Tumor in or near the lymph node.
  • Lymphoma.
  • Breast cancer may cause swollen axillary lymph nodes since the lymph vessels of the breast drain into the lymph nodes of the armpit. These nodes become enlarged when cancer cells spread beyond the breast tissue. The condition of the axillary lymph nodes is very important for staging of breast cancer which can help to determine the prognosis and clinical course of the disease, as well as indicate the best treatment option. Axillary lymph node status may be taken as the single most important factor which helps to determine the prognosis and  survival rate of patients with breast cancer.
  • Melanoma is one of the most dangerous types of skin cancer. It may metastasize (spread) to the nearby lymph nodes.
  • Brucellosis is also known as Undulant fever, Malta fever and Mediterranean fever. This disease is caused by the different strains of the Brucella bacteria which may infect animals such as goats, cows, pigs and dogs. It is spread to humans coming in contact with infected animals, eating or drinking unpasteurized dairy products. Flu-like symptoms may be present such as fever, headache, backache, joint pain, chills, fatigue and poor appetite. Muscle pain and swollen lymph nodes (including axillary lymph nodes) may be associated with this disease. Brucellosis may present as an acute infection or it may become chronic and can persist for years.
  • Perfumes, deodorants and certain cosmetic procedures like hair removal from the armpit may also cause an allergy or inflammation in the area with or without enlargement of the surrounding lymph nodes. Contact dermatitis, folliculitis or an armpit fungus may also develop on the skin of the axilla and cause swollen armpit lymph nodes.

Systemic Causes

Systemic causes of lymph node enlargement may be involved in causing swelling of the axillary lymph nodes before more generalized lymph node involvement becomes apparent.

These causes of axillary lymph node enlargement may include :

Viral

  • Infectious mononucleosis (Epstein-Barr virus) which produces symptoms of fever, sore throat and fatigue as well as enlarged lymph nodes.
  • Cytomegalovirus (CMV) – similar symptoms as mononucleosis.
  • Chicken pox (varicella).
  • Herpes zoster (shingles).
  • Measles.
  • Rubella (German measles).
  • Mumps.
  • HIV/AIDS.

Bacterial

  • Cat scratch disease.
  • Lymphadenitis – infection of the lymph nodes, which may be result as a complication of certain bacterial infections.
  • Ascending lymphangitis.
  • Tuberculosis.

Fungal

  • Sporotrichosis is a chronic skin infection caused by a certain type of fungus found in vegetations such as rose bushes and briars. Small, painless, red lumps appear following an injury, usually on the hands or arms, and may go on to involve the lymph nodes.

Side effects of vaccinations

  • MMR (measles, mumps, rubella) vaccination.
  • Typhoid vaccination.
  • Small pox vaccination.

Malignancy

  • Hodgkin’s lymphoma is cancer of the lymph tissue present in the lymph nodes, spleen, liver, bone marrow and other sites. It initially starts in a single lymph node , spreads to nearby lymph nodes and then to other organs such as the spleen, liver and bone marrow. Painless lymph node swelling of the axilla, neck or groin may be accompanied by fever, chills, night sweats, fatigue, weight loss, itching and various other symptoms.
  • Non-Hodgkin’s lymphoma.
  • Leukemia.
  • Breast cancer.
  • Lung cancer.
  • Melanoma.

Other causes

  • Allergic reaction to sulfur (sulphur) drugs, penicillin or iodine.
  • Jennifer

    I’m 18 years old. I’m not overweight, I don’t eat fast food a lot, and I exercise regularly. I feel soft swollen lymph nodes in my neck and on my left armpit. I have recently discovered that I have social anxiety disorder and has caused me to have shortness of breath, heart palpitations (in neck as well), muscle twitches, and eye twitches. Sometimes, I even cough when I’m done eating certain things. I have had at least 4 panic attacks so far which included me shaking uncontrollably. I don’t feel pain with these swollen lymph nodes but they are annoying because I’m so afraid. I feel so alone. I’m going to see a medical counselor about this on September 2nd. If I should get medication, will these swells go away for good?

  • Dr. Chris

    Hi Jennifer

    Swollen lymph nodes are a sign of many other underlying problems like an infection (common) or even cancer (rare). Sometimes temporary swelling may occur with no clear cut cause but should quickly go away. So there is no way to prescribe medication for it without identifying the cause. You need to be examined by a doctor and further tests may be necessary before a diagnosis can be reached. Refer to these articles for a list of possible causes :
    Swollen Neck Lymph Nodes
    Swollen Armpit Lymph Nodes

  • erimae24@yahoo.com

    I’m having issues with cintinuous staph infections in my lymph nodes of my armpits they go away and come back I don’t know what to do or what could be causing it

  • Dr. Chris

    Hi Erimae24

    You should see a doctor about this. Do not assume it is a staph infection unless a doctor has told you so and has taken a swab or scraping of the skin in the area or done a fine needle aspiration of the lymph node and sent it for laboratory assessment. The causes may vary. This could be related to a secondary infection of a skin rash in the area. Swelling of the lymph nodes can also be related to pathology within neighboring structures like the breast. Speak to your doctor about your problem if you have not already doe so. Further tests and investigations are necessary because antibiotics should have cleared up the infection.

  • Amel

    Hi,
    Im a 35 yrs old and i breastfeed my 16 month old and in my physical exam I was just told I have swollen lymph nodes in my right armpit. I really never noticed but when the dr felt it it did hurt a little. The dr said to do testings- mammogram and chest X-ray. Do I have to wait to wean my daughter? And could it be caused from breastfeeding too? Also I’m feeling a little nubness in my right hand, any relation?

  • Dr. Chris

    Hi Amel

    Yes it can be caused by breastfeeding. One of the possible causes is mastitis which is a breast infection that often arises in breastfeeding. You should speak to your doctor about your weaning concerns but it should not be a problem once off. Numbness is unlikely related unless the cause of the lymph node swelling is also affecting the nerves of the hand.

  • Shawn

    Hi, I am a 30 y/o male, in the military so I am very healthy, I weightlift 5 days a week and do cardio 3 days a week. My diet is a very healthy, high protein diet. About three days ago I felt a large lump in my armpit, about an inch or so in circumference. It wasnt painful at first but in the last day or so it has become sore. None of my other lymphnodes are swollen and I have no symptoms whatsoever of being sick. The lump is not hard, its ….squishy for lack of a better word. I am assuming I should see my doctor

  • Dr. Chris

    Hi Shawn

    Yes, you most definitely need to see a doctor. Without other signs and symptoms, its difficult to even give you a possible indication of what may be causing this. Despite the lack of symptoms, your doctor may be able to detect other important clinical features that you are not able to identify, which may give some indication of the causative condition.

  • Stephen

    I’m 25 year old male, in what I would consider good health. After work I noticed a lump in my left armpit while taking off my shirt. It’s slightly sore but the gland feels a bit swollen. Is this commonly a minor issue and could this be caused by physical injury, only affecting one arm?

  • Anni36

    Hi, I am a 28 year old woman without children so the breastfeeding and related issues can be ignored here. I have a swollen underarm lymph node and have had an itchy rash (not red) over my face, neck and upper arms for the past 2 months. My doctor gave me cortisone with a starting dosage of 6 pills. It isn’t really helping. Only the itching is better temporary for as long as the cortisone is working. I have lost 10 kg in the past 6 months. I usually see the weight difference at the end of my menstruation cycle but I didn’t change any of my eating habits in this time. I am still in a healthy weight range but I don’t know why I keep losing weight. I have also noticed increasing headaches. Only on 1 side of my head at its worst behind my eye. Most of these headaches are on the same side than the swollen lymph node. Should I be worried? Is there anything else I should be on the lookout for or should I ask my doctor for any specific tests?

    Thank you for taking the time to answer this.

  • Dr. Chris

    Hi Stephen

    It is unlikely a physical injury would have caused this without some clear sign of trauma on the skin surface (armpit skin). Infections are a more likely cause, either local or surrounding areas, but it can occur with no known cause for short periods of time. If it is persists past a day or so or gets worse, you should see a doctor. Take note of other signs and symptoms that may have appeared around the same time even if these conditions seem unrelated. You will need to report this to your doctor.

  • Dr. Chris

    Hi Anni36

    Unintentional weight loss with all these symptom may be a cause for concern. You should speak to your doctor soon. It may not be serious but nevertheless you cannot be sure unless you undergo the necessary tests. Your doctor may consider a complete blood count/full blood count as a starting point. This will help to indicate an infectious, autoimmune cause and so on. A mammogram is necessary as well. You say there are other related issues and this may also be relevant to your current symptoms even if you do not think so. Your doctor will able to advise you further. An HIV test is necessary given your symptoms.

  • Lisa

    29 year old female. I’ve nursed two children. Noticed a non fixed semifirm/squishy armpit lymph node during a self exam. I sometimes get pangs of discormfort that radiate down my left arm into my hand. I’ve had an ultrasound done to determine the node and several others are plugged. They’ve been this way for about 8 years since I discovered the largest one (about 1 inch in size). Should I have this further looked at or a biopsy performed? They haven’t gotten any larger but I do find the pangs of pain to be annoying.

  • Dr. Chris

    Hi Lisa

    Yes, a biopsy is definitely recommended even though it may not have grown. This may be contributing to the pain although there could be other unrelated conditions that are also a factor to consider here. The logical step would be to first investigate these nodes and then consider other causes.

  • brandon

    Hello, my name is Brandon! Recently a lump appeared in my left armpit! At first it was soft to the touch, then after ignoring it for a couple of weeks it burst and leaked a cloudy puss! It is still leaking daily but not as much! There are also a couple other lumps that are slightly sensitive to the touch! What is wrong??

  • megan

    I am a 23 y/o female with a painful soft lump in left armpit. It’s not hard or a defined lump. I’m not sure how long its been there but the last few months the pain got worse and it has gotten slightly bigger. Any ideas?