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Painful armpit lumps are often due to a swollen lymph node under the armpit. This is usually a sign that the body is fighting an infection, but it can sometimes indicate cancer. Cysts and fatty growth can also form lumps under the arm.

Fortunately, there are many treatments for lumps that appear under the arm, depending on what has caused them. A doctor can diagnose the underlying cause of an armpit lump and prescribe the proper treatment.

There could be a number of potential causes of armpit lumps. Most armpit lumps are harmless and the direct result of abnormal tissue growth.

However, armpit lumps may indicate a much more serious underlying health issue. If this is the case, it will most likely require medical intervention.

[doctor inspecting a lump in an older woman's armpit]Share on Pinterest
Most armpit lumps are harmless, but occasionally they can indicate a more serious condition.

Some of the most common causes of armpit lumps include:

  • noncancerous, fibrous tissue growth (fibroadenoma)
  • cysts or fluid filled sacs
  • allergic reactions to deodorant, antiperspirant, or soap
  • viral or bacterial infections
  • infections that drain into the lump in the armpit
  • fatty growths (lipomas)
  • adverse reactions to vaccinations
  • fungal infections
  • lupus
  • breast cancer
  • lymphoma
  • leukemia

The most obvious symptom of an armpit lump is the lump itself. The lumps can range in size from very tiny to quite large.

The texture of the armpit lump may vary according to what is causing it. For example, a cyst, infection or fatty growth may feel soft to the touch. However, fibroadenomas and cancerous tumors may feel hard and immobile.

Some people may experience pain with an armpit lump. Painful lumps are often associated with infections and allergic reactions, which cause softer lumps. Lymph node infections may also cause painful lumps in the armpit.

The infections can cause the following symptoms to occur with the armpit lump:

  • swelling throughout the lymph nodes in the body
  • fever
  • night sweats

Lumps that change in size gradually or that do not go away may be symptoms of more serious conditions such as:

  • breast cancer
  • lymphoma
  • leukemia

Differences in men and women

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Although both men and women of all ages can get armpit lumps, women should pay special attention to lumps in this region as they may indicate breast cancer.

Armpit lumps occur in both men and women of all ages and many of these are harmless. However, women should be particularly aware of armpit lumps as they may indicate breast cancer.

Women should perform monthly breast self-exams and see a doctor for routine exams. If a woman finds a lump, she should report the lump to her doctor right away.

A man can generally wait to see a doctor unless they notice warning signs indicating the lump is serious. This is because men are far less likely to find a lump in the armpit that is due to breast cancer. However, although rare, men can also develop breast cancer.

Any new or newly discovered lump on the body could cause concern. However, not all lumps are harmful or even painful. The seriousness of a lump can be best determined through medical examination and sometimes additional testing.

Warning signs that may indicate a more serious armpit lump include:

  • gradual enlargement
  • no pain
  • does not go away

If a person experiences or notices any of these symptoms, or has any doubts about the lump, they should see their doctor as soon as possible who can rule out more serious causes. Of course, any unusual lumps should be carefully evaluated.

What happens next

When a person sees a doctor about an armpit lump, the doctor will generally start by asking them questions about the lump. The doctor may ask about any pain or discomfort the person is experiencing.

In addition, the doctor will perform a physical examination. This examination should include a hand palpation or massage to determine the consistency and texture of the armpit lump. This procedure allows the doctor to thoroughly examine the lymph nodes.

Only a doctor can determine whether an armpit lump is serious or not. A doctor may be able to diagnose the cause with just a simple examination.

In other cases, a doctor may request that the person monitor the lump closely to check for any changes over time.

Sometimes, a doctor will order additional tests to help rule out other causes, such as allergic reactions, infections, and cancer. These tests might include:

  • allergy testing
  • complete blood count that measures the number of red and white blood cells
  • biopsy removing a small piece of tissue from the lump for testing
  • chest or breast X-ray (mammogram)

Non-harmful lumps may require no further actions. Bothersome or harmful lumps will almost certainly entail some form of treatment.

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If the lump is a symptom of a minor condition, such as an allergy or infection, a doctor may recommend over-the-counter creams or medications.

Many people have armpit lumps that do not require any treatment. A doctor may simply monitor the lump and ask the person to report any changes they experience.

For people with armpit lumps that do not need formal treatment, the doctor may recommend home remedies. Many of these can be bought online, such as:

  • warm compresses or heat packs.
  • over-the-counter creams
  • pain relief medication, such as ibuprofen.

Lumps caused by allergic reactions will clear up when the allergen is removed. If the lump is caused by a bacterial infection, the doctor will probably prescribe antibiotics to clear the infection. The armpit lump should reduce in size and eventually disappear.

Simple procedures may be required to remove fatty lumps or cysts. These procedures are often short and present minimal risk to the person.

What if the armpit lump is cancerous?

Unfortunately, some lumps have more serious causes, such as cancerous tumors.

If this is the case, a doctor will need to consider treating the cancer. Treatment options will be similar to treatment for many other types of cancer. Some possible treatment options include:

The outlook for an armpit lump depends largely on the cause.

For example:

  • A lump caused by a viral infection will usually go away as the infection clears up.
  • Lumps that result from allergic reactions should also clear up once the allergen is removed or reduced.

However, some armpit lumps will not disappear without treatment.

For example:

  • A lipoma is not harmful, but will not go away on its own. As a result, lipomas require medical help to remove.
  • Lumps caused by cancer vary in terms of successful outcome.

Factors that may affect the outlook for someone with a cancerous lump under their arm are:

  • the stage of the cancer when first treated
  • whether the cancer has spread to other parts of the body

As with all cancer types, early detection is important to help increase the chances of successful remission.

Ultimately, determining the cause of the armpit lump is vital in terms of treatment and outlook. When a lump is discovered, it is always a good idea to consult with a doctor to determine the exact cause and decide what needs to be done in terms of treatment.