Armpit Lump Causes

What is an armpit lump?

Most people will get a lump in one of their armpits at some point during their lives. For most people, these aren’t anything to worry about and often clear up by themselves. In some cases, however,  it is necessary to seek medical intervention to determine the cause of the lump and to treat it. The most likely cause of an armpit lump is a swollen lymph node which can occur due to infection, or in rarer cases, as a result of cancer. 

Symptoms of armpit lump

• Redness under the arm
• Tenderness and pain in the armpit
• Painless lump under the arm
• Pain travelling down the arm
• Itchiness

Causes of armpit lump

Common causes of armpit lumps include: 

• Swollen lymph nodes

Lymph nodes are small structures that are part of the body’s immune system. They contain white blood cells that help the body fight against infection and disease. If swollen, you may be able to feel them in your armpit, groin or neck. They can feel tender or painless to touch, rubbery and roughly bean-shaped. 

Enlarged lymph nodes are the most common explanation for a lump in the armpit. Swollen lymph nodes often indicate that the body is fighting some type of infection near the swollen gland.¹ The infection could be caused by something simple like a common cold virus,usually going away within a couple of weeks without needing any treatment. 

• Cysts

Skin cysts are lumps under the skin filled with fluid and are usually harmless. They often appear yellow or white due to the pus contained within them. Cysts usually go away on their own, in which case applying a warm compress can ease the discomfort caused by the cysts as they heal . If a cyst is not healing and is causing you pain, you should consult a medical professional, as it may be necessary to remove the cyst.

• Irritation

Irritation from products such as deodorants and soaps can also cause lumps in the armpit, especially after shaving. These lumps are likely to be close to the surface and might be itchy or cause mild pain. These should clear up quickly, and you should simply discontinue use with a product if you have a reaction to it. 

Ingrown hairs can also irritate  the skin in the armpit, so lumps are more likely to occur if you  remove the hair in this area. These may become painful if infected, and if it doesn’t clear up by itself, you may need to consult your healthcare provider. 

• Hidradenitis suppurativa

This painful, long-term skin condition can cause abscesses in the armpit alongside other areas of the body with sweat glands, such as the groin. This condition affects around 1 in every 100 people and is more common in those assigned female at birth. The condition causes various fleshy, painful lumps to grow on the skin ranging from large boil-like lumps to small  blackheads. The exact cause of Hidradenitis suppurativa is unknown; however lumps can form due to blocked hair follicles.

• Cancer 

In some cases, a lump in the armpit can also be a sign of cancer, particularly lymphoma, which is a type of blood cancer. The most common symptom of lymphoma is swelling of lymph nodes in the armpit, groin or neck. Lymph nodes are normally quite soft to the touch, so hardening of these glands can indicate that something is wrong.²  Swollen lymph nodes resulting from cancer are usually painless and very rarely disappear by themselves. Often, a swollen lymph node is one of the earliest signs of lymphoma and isn’t accompanied by other symptoms. 

Often, a lump in the armpit is just a swollen lymph node and is often linked to other causes of armpit lumps, such as an infection. For example, if an ingrown hair was to become badly infected, lymph nodes in the immediate area could become swollen in response to the infection. 

Differences in men and women

For those that are breastfeeding, a lump in the armpit can sometimes occur as a result of a plugged duct. This occurs because the milk glands can become over-distended with breast milk.³ The NHS website has advice on what to do if you experience a clogged milk duct or other breastfeeding-related issues. 

A lump in the armpit can sometimes be a symptom of breast cancer. This may or may not be accompanied by other breast cancer symptoms, such as a lump in the breast tissue. Although breast cancer most commonly affects people assigned female at birth, it can also affect people assigned male at birth, so everyone should be vigilant if they have a persistent armpit lump or any other signs of the disease.

Diagnosing armpit lumps

Most armpit lumps will go away by themselves within a few days. However, if the lump persists for more than two weeks, it will be necessary to contact your doctor. Here, the doctor or healthcare provider will be able to determine the best course of action. 

They will most likely feel the lump to establish whether it is soft or hard, if it feels superficial or deep under the skin, and to detect any other lumps that might be present. Blood tests can be carried out to detect infections if it’s suspected that this might be the cause of the lump. 

In some cases, however, it may be necessary to have a biopsy of the lump to see what it contains, particularly if there is a suspicion that it may be related to cancer.

Can armpit lumps be prevented?

There isn’t a straightforward way to prevent armpit lumps because they can be caused by different things. For lumps caused by irritation and as a result of shaving, it is best to exfoliate your skin before hair removal; this makes it less likely that ingrown hairs will occur. 

Treating armpit lumps

Most armpit lumps don’t require treatment as they will subside on their own. As mentioned previously, however, if the lump persists for more than two weeks, it will be necessary to consult a doctor to assess the cause of the lumps and to treat these. For example, if these are caused by an infection , antibiotics may need to be prescribed. 

If armpit lumps have formed due to an ingrown hair or irritation, there are measures that you can take at home to help treat these, including the application of a clean, warm compress and a topical antiseptic cream. 

When to see a doctor

It is always important to be aware of any unusual changes in your body, such as any lumps or swellings that won’t go away. Lumps in the armpit are likely to have a benign cause and go away by themselves within a week or two. However, if the lump persist sis causing you particular discomfort, or is accompanied by a fever, you should get advice from your healthcare provider as soon as possible. 

Summary

Lumps in the armpit are not uncommon and are caused mainly by swollen lymph nodes. Lymph nodes can become swollen in response to infection and, in some cases, as a result of cancer, particularly lymphoma. Nevertheless, there are other less severe causes of armpit lumps, such as ingrown hairs and irritation from shaving.

In some cases, antibiotics must be prescribed to clear the infection causing the lump, but most lumps will clear up by themselves in approximately a week or two. For people that are assigned female at birth, the lumps can indicate a clogged milk duct if they are breastfeeding, or a breast infection. Breast cancer is also a cause of armpit lumps and so everyone, regardless of their gender, should be aware of this.
Overall  it’s important to seek medical advice if you notice any persisting or painful lumps  on your armpit