What is an Armpit Lump?

An armpit lump is a swelling or bump in the armpit that may have many causes. These can most commonly be due to infections, causing swelling of the lymph nodes or a growth due to cancer. Other causes include cysts of the hair follicles.

Swollen lymph nodes are the most common cause of armpit lumps. These lymph nodes are distributed throughout the body and are major components of the immune system that fights off infections and other diseases. Armpit lumps are generally not serious and usually do not require any treatment. However, serious causes like cancer require urgent therapy.

What Causes Armpit Lumps?

The development of a lump in the armpit may have many causes. Some of these are briefly highlighted below:

  • Swollen Lymph Nodes: The armpit has a large aggregation of lymph nodes, which act as filters for trapping infectious microbes as well as cancerous tumor cells. This results in swelling of the lymph nodes which manifest as lumps in the armpits. These lumps may be painful or painless.
  • Infections: These may include bacterial infections of a cystic gland of the armpit. Rarer infections include viral infections such as Human Immunodeficiency Virus (HIV), which causes Acquired Immune Deficiency Syndrome (AIDS), Herpes Simplex Virus (HSV) causing sores, as well as Epstein-Barr Virus (EBV), which causes infectious mononucleosis. Other causes may be a fungal infection.
  • Cancer: This may include breast cancer, lymphoma or leukemia.
  • Fibroadenoma: These are non-cancerous fibrous tissue breast tumors, which most often occur in young women. These women may also experience painful armpit lumps.
  • Lupus: This is an autoimmune disease in which the immune system attacks the body’s own cells and tissues. Lupus can cause swollen lymph nodes throughout the body, including the armpits.
  • Allergic Reactions: These can occur due to the skin irritation due to shaving of the armpits and can give rise to very painful lumps in the armpits. These can also arise by using antiperspirants and certain types of bath soaps.
  • Cysts: These are fluid-filled sacs, which can give rise to armpit lumps.
  • Lipoma: These are harmless growths of fatty tissue that can manifest as lumps.
  • Vaccine Adverse Reactions: Sometimes, adverse reactions due to vaccination can occur, which can lead to swelling of the lymph nodes.
What Can Cause Armpit Lumps?

How will the Armpit Lump Look Like?

The lump itself is the most prominent symptom. The lump may exhibit the following characteristics:

  • Size: It may be tiny (pea size) or relatively large (about the size of a golf ball).
  • Texture: It may be soft or hard. Soft lumps are caused by cysts, infections and lipomas, and are softer and tender. Hard lumps are caused by fibroadenomas and cancerous tumors, and are hard to touch.
  • Mobility: The lump may move about or may be immobile. The lump may be under the skin or may hang off the skin. Cancerous lumps sometimes can be fixed and do not move around.
  • Sensation: Armpit lumps caused by tumors are generally painless but sometimes can be painful. Lumps due to allergic reactions or infections are generally painful. Inflamed and tender skin is usually present over the swollen lump. There may also be pain in the arm and chest, as well as discomfort while moving the affected arm.

The other major symptoms and signs include the following:

  • Rash, irritation, inflammation, and itchiness in the armpits.
  • Fever due to systemic infections.
  • Lumps in other parts of the body, especially the groin.
  • Scarring.
  • Foul smelling drainage.

What are the Consequences of an Armpit Lump?

The major consequences of an armpit lump include the following:

  • Pain and Discomfort: These are the primary consequences of an armpit lump.
  • Difficulty in Performing Tasks: Restricted mobility of the affected arm can result in difficulty in performing everyday tasks.
  • Fever: In the case of bacterial and viral infections, fever may be a problem.
  • Abscess: In severe bacterial infections, an abscess may be a major complication.
  • Absenteeism: Armpit lumps could result in absenteeism from school, college or office.


  1. Armpit Lump - MedlinePlus, U.S. National Library of Medicine, National Institutes of Health (NIH), USA - (https://medlineplus.gov/ency/article/003099.htm)
  2. Breast Cancer Symptoms: What You Need to Know - (https://www.cancer.org/latest-news/breast-cancer-symptoms-what-you-need-to-know.html)
  3. Lumps - National Health Service (NHS) - (https://www.nhs.uk/conditions/lumps/)

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