Armpit Lump

What is an armpit lump?

With an armpit lump, it feels as if there’s a pea or other growth under your skin in the upper-most area of your inner arm. Lumps can develop in men and women of all ages. There can be many reasons for an armpit lump, and most of them aren’t serious.

What does a lump under the armpit mean?

In rare cases, an armpit lump can be a sign of cancer. More often, they’re due to irritation, blockages or injuries affecting:

• Hair follicles.
• Lymph nodes.
• Muscle.
• Skin.

What does an armpit lump feel like?

An armpit lump may feel hard, soft or unusually warm.

What other symptoms might I have?

You may have a fever, along with pain and redness in the area. The lump may also:

• Contain pus.
• Get larger when you’re physically active and shrink at rest.
• Move a little when you press on it.

What are the possible causes of an armpit lump?

One of the more common causes is swollen lymph nodes. People with lupus also frequently experience swollen lymph nodes that cause armpit lumps.

Additional causes may include:

Cancer and noncancerous (benign) tumors

• Adult soft tissue sarcoma.
• Breast cancer.
• Fibroadenomas of the breast.
• Leukemia.
• Lymphoma.

Hair follicle issues

• Blocked/inflamed hair follicles (hidradenitis suppurativa).
• Boils and carbuncles.
• Cysts, like an epidermal inclusion cyst or pilar cyst that forms around hair follicles.
• Folliculitis.
• Ingrown hairs.

Injuries

• Over stretching.
• Trauma from a collision, fall or other situation that forcibly pulls your arm (brachial plexus injury or muscle injury).

Skin issues

• Lipomas (collections of fat cells).
• Impetigo.
• Irritation from shaving.
• Rash.
• Skin tags.

Viral infections

• Influenza (the flu).
• Mononucleosis.

Why would I have a swollen lymph node in my armpit?

Lymph nodes are located throughout your body, including your armpits. They contain white blood cells that help your immune system fight infections. When your body detects bacteria and viruses, they get trapped in your lymph nodes, causing temporary swelling.

Can a vaccine cause an armpit lump?

A small number of people get an armpit lump after receiving a vaccine. This may include the COVID-19 vaccine or flu shot. The armpit lump often appears on the side of your body where you received the shot.

These armpit lumps occur because the vaccine triggers an immune system response that produces antibodies. This type of lump is a sign that the vaccine is helping you build immunity. It typically goes away in a few weeks.

What does a cancer lump feel like in the armpit?

These lumps tend to be painful, nonmobile and hard to the touch. But finding one doesn’t always mean you have cancer. A complete evaluation, including imaging tests and a potential biopsy, is typically necessary to make a diagnosis.

What types of treatments are necessary?

Watchful waiting, meaning monitoring instead of treatment, may be the right option for lumps that are likely to go away on their own.

If you need treatment, care may include:

• Antibiotics may be necessary if you have an infection.
• Over-the-counter pain medications and nonsteroidal anti-inflammatory medicines relieve discomfort if the lump is painful or the area around it is swollen.
• Removing the lump may be necessary if it’s due to lipomas, cysts or other skin issues.

What is the prognosis for armpit lumps?

Most armpit lumps go away on their own, but it can take a few weeks. It’s possible to develop a new armpit lump if you get another infection, receive a vaccine or experience a skin issue. But most lumps are harmless.

When should I worry about a lump in my armpit?

You should contact your healthcare provider if the armpit lump:

• Doesn’t go away after two weeks.
• Feels hard and painful.
• Gets bigger.
• Grows back after being removed.
• Is accompanied by a fever or other signs of infection.
• Suddenly causes new symptoms like being tender to the touch.

A note from Cleveland Clinic

It can be concerning to find a lump in your armpit. But most are harmless and go away on their own. Armpit lumps are often a sign of infection that may require antibiotics. Some lumps are due to skin issues and need to be removed. Rarely, an armpit lump can be a sign of cancer. If you’re worried about a lump, the best thing to do is contact your healthcare provider. They can determine what’s causing it and provide treatment if necessary.