If You Have a Lump in Your Armpit, Here’s What It Could Mean

These lumps in the armpit are common. And while they're often benign, they can indicate a more serious underlying problem. This is why you should pay close attention.

armpitOlena Yakobchuk/Shutterstock

So, you’ve found a lump in your armpit

You’re showering up and…wait…is there a lump in your armpit? It’s natural to be worried—we’ve been taught that lumps and bumps aren’t normal—but before you go down the Google rabbit hole, know this: It’s probably no big deal. Most of the reasons for a lump in the armpit are pretty innocuous.

It’s a cyst

If you regularly shave your underarms, the irritation to this tender skin and hair follicles can lead to a cyst or abscess. If you have a cyst, the lump in your armpit may be painful. If that’s the case, see your doc who can recommend a number of treatments, says the Mayo Clinic, including injections to reduce swelling, drainage, or even surgical cyst removal. Learn more about cysts, boils, ingrown hairs, and other skin mysteries.

It’s a lipoma

First, remember that a lipoma—a benign fatty growth—is not lymphoma, a type of cancer. (That should ease your fears.) To know if it’s a lipoma that you have, give it a touch. According to the Cleveland Clinic, it’s like a “rubbery bulge that feels like it can move.” Lipomas are slow-growing and affect 1 in 1,000 people, particularly those in middle-age. A lipoma may not have to be treated at all unless the lump in your armpit truly bothers you, in which case, your doctor can remove it.

It’s an infection

You’ve got lymph nodes throughout your body, and these handy immune system sentinels can filter out viruses and bacteria. When you’re saddled with an illness, they can swell—and there happen to be lymph nodes in your armpits. You may find that the lump in your armpit is tender and the size of a pea or bean, says the Mayo Clinic. However, the underlying cause can be any number of problems, from a run-of-the-mill cold to more severe problems, like HIV, mono, lupus, or rheumatoid arthritis.

It’s an inflamed sweat gland

Everyone knows about sweaty pits. When sweat-producing glands or hair follicles get clogged, bacteria can sweep in and produce a cyst that later bursts, infecting even more follicles. If the cycle repeats, it can develop into a chronic skin condition called hidradenitis—this hits up to three percent of people in the United States, explains Hopkins Medicine. This network of cysts may be itchy, painful, and even impact your quality of life. Although there’s no cure for hidradenitis, your doctor can prescribe medication or other therapies like laser hair removal to improve your comfort.

It’s a breast infection

If you’re currently breastfeeding, you’ve no doubt heard the horror stories about mastitis, an inflammation of breast tissue. You may feel swelling, pain, and lumps in your breast, but the infection can also enlarge the lymph nodes in your armpit, notes the U.S. National Library of Medicine. Women often commonly feel as if they have the flu. (Note: if you are not breastfeeding but think you have this type of infection, see your doctor. She will want to rule out other, serious causes, including breast cancer.)

It’s cat scratch disease

Weirdly, cat scratch fever is a real thing. This funny-sounding condition is one of the possible culprits behind an armpit lump, according to MedlinePlus. About half of cats carry a bacterium called Bartonella henselae, which they can spread via a scratch. Once the bacteria enters your skin, you can develop an infection that causes the lymph nodes in your underarm to swell. The treatment? Wait it out, or if it persists, antibiotics.

When you should call your doctor

There’s no reason why you should suffer with a lump in your armpit, especially if you’re feeling pain. And although your armpit lump is most likely a treatable skin issue like a cyst, occasionally it can be an indication of cancer—such as breast cancer, which can spread to lymph nodes in the armpit. A lump in the armpit is also one of the most common signs of Hodgkin lymphoma, a type of cancer that originates in white blood cells, according to the American Cancer Society; the other lymph nodes that may swell include the ones in the neck or groin. If you’re concerned for any reason or symptoms are getting worse or not going away, make an appointment with your doctor—especially if you notice any of these strange symptoms that can signal serious disease.