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Armpit lump

An armpit lump is a swelling or bump under the arm. A lump in the armpit can have many causes. These include swollen lymph nodes, infections, or cysts.


Lumps in the armpit may have many causes.

Lymph nodes act as filters that can catch germs or cancerous tumor cells. When they do, lymph nodes increase in size and are easily felt. Reasons lymph nodes in the armpit area may be enlarged are:

  • Arm or breast infection
  • Some body wide infections, such as mono, AIDS, or herpes
  • Cancers, such as lymphomas or breast cancer

Cysts or abscesses under the skin may also produce large, painful lumps in the armpit. These may be caused by shaving or use of antiperspirants (not deodorants). This is most often seen in teens just beginning to shave.

Other causes of armpit lumps may include:

  • Cat scratch disease
  • Lipomas (harmless fatty growths)
  • Use of certain medicines or vaccinations

Home Care

Home care depends on the reason for the lump. Check with your health care provider to determine the cause.

When to Contact a Medical Professional

An armpit lump in a woman may be sign of breast cancer, and it should be checked by a health care provider right away.

Call your health care provider if you have an unexplained armpit lump. Do not try to diagnose lumps by yourself.

What to Expect at Your Office Visit

Your health care provider will examine you and gently press on the nodes. You will be asked questions about your medical history and symptom, such as:

  • When did you first notice the lump? Has the lump changed?
  • Are you breastfeeding?
  • Is there anything that makes the lump worse?
  • Is the lump painful?
  • Do you have any other symptoms?

You may need more tests, depending on the results of your physical exam.

Alternative Names

Lump in the armpit; Localized lymphadenopathy - armpit; Axillary lymphadenopathy; Axillary lymph enlargement; Lymph nodes enlargement - axillary; Axillary abscess


Armitage JO. Approach to the patient with lymphadenopathy and splenomegaly. In: Goldman L, Ausiello D, eds.Cecil Medicine

Tower RL II, Camitta BM. Lymphadenopathy. In: Kliegman RM, Stanton BF, St. Geme JW III, Schor NF, Behrman RE, eds.Nelson Textbook of Pediatrics

Update Date 8/18/2013

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