Lump in Armpit

What is a Lump in Armpit?

A lump in armpit is usually an enlarged lymph node or several nodes under the armpit. Lymph nodes are small glands that are located all over the body and they can become enlarged due to various reasons, like infection, cyst or irritation. A lump in the armpit can also indicate a serious health condition, like cancer.

In most cases enlarged lymph node becomes normal sized after a while. If the lymph node continues to be enlarged or is growing in its size, it could indicate a more serious condition [1].

The lymphatic system

One of the parts of human circulatory system, besides the cardiovascular system is lymphatic system. Lymphatic system is almost parallel to blood vessels. It moves lymph between tissue and bloodstream through a system of lymph ducts, lymph nodes, lymph vessels and organs. Adenoids, spleen, thymus and tonsils are all part of the lymphatic system. Its two main components are lymph and lymph nodes.

Lymph is a clear fluid, which is mainly made up of white blood cells. These cells attack foreign bodies in the bloodstream and fight infection. Lymph is also present in intestines, where it holds proteins and fats.

Lymph nodes or lymph glands are small, round-shaped bodies that are present in groups in several locations, like tissue behind breast, armpits, neck and groin tissue, as well as several other locations. These glands are interconnected with lymphatic vessels and they serve as the place where bacteria and other foreign substances are removed. If there is an antibody present, specialized antigen-fighting cells will be produced in the lymph node and sent out in the bloodstream to fight it. Because of this activity, lymph nodes get enlarged during an infectious process [2].

axillary lymph nodes

Causes of lump in armpit

Lump in the armpit is likely to be a lymph node, which is swollen and enlarged due to an infection. In rare cases, it can be caused by lymphoma. If the lump is small and knobbly, it might be a skin tag. Other common causes include:

  • Lipoma- fat tissue growth, which is usually benign
  • Fibroadenoma- non-cancerous growth of fibrous tissue
  • Injury to armpit, hand or arm
  • Hidradenitis
  • Brucellosis-bacterial infection that can be contracted upon contact with dogs, cows, cats and other mammals. .
  • Cat scratch disease- infection caused by bacteria that can be transferred by a cat piercing the skin
  • Allergic reaction, also includes reaction to silicone breast implants
  • Viral infections- mononucleosis, chicken pox, HIV/AIDS
  • Fungal infection
  • Adverse reaction to vaccination
  • Breast cancer response
  • Leukemia
  • Non-Hodgkin’s or Hodgkin’s lymphoma
  • Melanoma
  • Lupus, which can also cause Antiphospholipid Antibody syndrome[1,3]


Usually, a lump in the armpit is harmless and is a reaction due to viral or bacterial infection. The patient can self-check at home and seek for medical attention if there are some worrying signs. The self-check questions should include:

  • The age of the lump- new lump can be a sign of an ulterior process in the body, but if the lump has been there for several years, it is most likely scar tissue. Cancerous lumps usually grow larger in size with time.
  • Disease history- recent infection causes response from the immune system which can manifest in enlarged lymph nodes. There might be several other enlarged lymph nodes, mainly in the head and neck area. Insect bite, shaving, sunburn can cause lymph nodes to swell. These lumps usually disappear in a matter of several weeks.
  • Recent vaccination or allergy to medications- if the patient has started taking new medication or has recently vaccinated for smallpox, typhoid or/and measles/mumps/rubella, there is a chance that lymph node gets swollen.
  • Pain and growth- if the skin on top of the lump is red and painful, it could mean that it is a local infection (similar to a pimple). An infected lymph node is usually soft, painful and movable. Cancerous lymph nodes tend to be hard and painless, as well as fixed in the place. Cancerous lumps are usually connected to other lumps. These lumps grow in size and do not go away [4].

enlarged axillary lymph nodes - lump in armpit


If the lymph node does not go away on its own, it is important to diagnose the underlying cause. The diagnosis can be made by doing several procedures.

Medical history

Medical history is very important to determine the further course of action. The conditions of how and when the lymph node got swollen can lead the doctor to the diagnosis. After completing medical history, several other investigations can be ordered.

Physical examination

Physical examination will include checking the swollen lymph node for its size, consistency, as well as the visible signs on the skin, like redness, swelling or warmth. The doctor will also check other palpable lymph nodes in the body, as well as check other organ systems.

Laboratory investigations

After medical history and physical examination, the doctor will have a possible idea about what is causing the lymph node to be swollen. Afterwards, blood analyses can be ordered. These usually include complete blood count to evaluate the overall health and exclude infectious process. There are also several analyses that can diagnose a specific condition. These might include cancer markers. Allergy tests can also be performed.

Lymph nodes can also be biopsied. A sample or the entire lymph node is taken and checked for malignant cells and other microscopic signs.

Imaging studies

Imaging studies of the affected area can help to determine the underlying cause. Usually X-Ray imaging of chest and mammogram is performed. CT imaging can also be used. The enlarged lymph node can also be visualized with ultrasound imaging. It can reveal a lot about the consistency and size of the lymph node, as well as the surrounding tissue [5].

enlarged axillary lymph nodes in CT scan

Treatment of lump in armpit

The treatment for swollen lymph nodes is usually based on the underlying condition. Usually, the lymph node is enlarged due to an infectious process and it will shrink in size after infection resides. Antibiotic treatment can also be used for infection. If the lump is painful, non-steroid anti-inflammatory medications can relieve pain and inflammation. Also, warm compress can relieve discomfort.

In case the lymph node is enlarged due to cancer, depending on the type and stage of the cancer several treatment methods can be used. these include chemotherapy, radiation therapy and surgery [1,6].


lump in armpit image

lump in armpit


  1. General information:
  2. Lymphatic system:
  3. Causes:
  4. Symptoms:
  5. Diagnosis:
  6. Treatment:


  1. I have the same lump… I soothe it with warm water using a cloth.. and it popped and oozed pas.. it’s not getting smaller… thank you

  2. I have had a lump under my arm for several months now. It does not hurt. I had an ultrasound and it revealed nothing but the lump is still there and it appears to be a little bigger. Not by much really. I see my primary in a couple of weeks. I guess I should have her look at it again. :-/

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