Armpit Lump: Causes, Diagnosis & Treatment

Armpit Lump

What Is an Armpit Lump?


  1. The lymph nodes are located under your arm. This is why many people, especially women, get nervous when they find an armpit lump.
  2. The lumps can be caused by bacterial or viral infections, allergies, harmless fat or tissue growths, and cancerous growths.
  3. Your doctor will conduct a physical examination and may order a biopsy to determine the cause of the lump.

An armpit lump usually refers to the enlargement of at least one of the lymph nodes under your arm. Lymph nodes are small, oval-shaped glands that are located throughout the body and play an important role in your body’s immune system.

The lump may feel small. In other cases, it may be extremely noticeable. Armpit lumps may be caused by cysts, infection, or irritation due to shaving or using antiperspirants. However, these lumps may also indicate a serious underlying health condition.

Seek medical attention if you have an armpit lump that gradually becomes enlarged, isn’t painful, or doesn’t go away.

Causes of Armpit Lumps

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Most lumps are harmless and are usually the result of abnormal tissue growth. However, armpit lumps can be related to a more serious underlying health problem. Any unusual lumps should be carefully evaluated by a doctor.

The most common causes of armpit lumps are:

  • bacterial or viral infections
  • harmless fat tissue growths (lipomas)
  • allergic reactions
  • adverse reactions to vaccinations
  • fungal infections
  • noncancerous fibrous tissue growth (fibroadenoma)
  • breast cancer response
  • cancer of the lymphatic system (lymphoma)
  • blood cancer in the bone marrow (leukemia)
  • lupus or SLE (an autoimmune disease that targets your joints and organs)

Armpit Lumps in Women

In Women

Armpit lumps can occur in men and women of all ages. However, a lump under the arm might indicate breast cancer. Women should perform monthly breast exams (best to do after period ends) and report any lumps to a doctor right away. 

Note that breasts undergo hormonal changes during the menstrual cycle, and may tend to feel more tender or lumpy during this time. This is completely normal. For the most accurate results, perform breast self-exams about one to three days after your period ends. 

Diagnosing Armpit Lumps

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A thorough physical examination is the first step in diagnosing an armpit lump. Your doctor will ask you questions about any changes in the lump, as well any pain you’re experiencing in the area. Palpation, or massage, is used to determine the consistency and texture of the lump. This method is done exclusively by hand, as the doctor works to gently examine the lymph nodes.

In some cases, a physical exam may provethe lump isn’t harmful. For example, benign lumps, such as lipomas, don’t require additional treatment. If a lump is bothersome, however, a doctor can recommend treatment options to remove it.

Based on the results of your physical examination, your doctor may order further testing to rule out infection, allergic reaction, or cancerous changes. Your doctor may order a combination of the following diagnostic tests:

  • complete blood count: to measure the number of red and white blood cells in your system
  • chest or breast X-ray (mammogram): this is an imaging test that will allow your doctor to better see the lump
  • biopsy (removing a small piece of tissue from the lump for testing)
  • allergy testing

Treating Armpit Lumps

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The course of treatment your doctor recommends will depend on the underlying cause of the lump. Bacterial infections can be treated with oral antibiotics. After several days, the armpit lump should start to disappear as your body fights the infection.

If your lump is associated with allergies, it should subside once you start medication and learn to avoid your allergy triggers.

In most cases, armpit lumps won’t require any treatment, just simple observation. You can use home remedies such as warm compresses and over-the-counter pain relievers to ease any discomfort. Lumps that don’t require treatment include those associated with:

  • lipomas
  • viral infections
  • fibroadenoma (noncancerous breast lumps)

If your armpit lumps are found to be cancerous, your doctor may refer you to a specialist for further care. Treatment will depend on the type of cancer and what stage you’re in, and it may involve a combination of:

  • chemotherapy
  • radiation therapy
  • surgery

Outlook for Armpit Lumps

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The outlook for an armpit lump depends on its cause. For example, a lump that stems from a viral infection will eventually go away on its own. However, a lipoma, while harmless, is permanent.

The outlook for an armpit lump caused by cancer will depend on a variety of factors, including the stage of cancer and whether the tumors have spread to other parts of the body. For the best chance of recovery, it’s important to obtain a timely diagnosis.

Even if you don’t think the lump is harmful, it’s best to contact your doctor for an accurate diagnosis.

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