One morning, I awoke with a tender knot in one of my breasts. The knot was the size of a walnut. It turned out to be a breast cyst.

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Earlier this year, I headed in for my annual mammogram. I got my boobs squished and photographed and didn't think twice about it until I got a call a few days later. My doctor told me there was an unusual finding in both breasts, and I needed to come back in for more imaging.

Needless to say, that sent a shock of alarm through me. Since mammograms are meant to detect cancer, my first fear was a tumor. But my doctor assured me my mammogram didn't indicate that. Whatever the radiology team saw, they didn't think it was an emergency; just something that needed a second look.

I Have Lumps in My Breasts, But They Aren't Cancer—Here's What It's Like Living With Breast Cysts , Portrait of young woman performing a breast self-examination over gray background.
Credit: Getty Images

I scheduled a follow-up ultrasound to get a closer look at the inside of my breasts. There on the ultrasound screen, I could see that my breasts contained several pockets of fluid. The radiologist explained to me that I was seeing a cluster of totally benign breast cysts. I gave a sigh of relief, then got dressed and texted my husband to say I had breast cysts… again. This was the third time I'd been down this road.

The first time I noticed a cyst, it was when I was in my early 30s. I was weaning my son and my breasts were changing rapidly as my milk production slowed down. At one point, I noticed a large, painful mass that I assumed was a blocked milk duct. When it didn't go away, I called my doctor and went in for a mammogram and ultrasound. Those tests confirmed that it was a cyst, and I went to a breast specialist to have it drained.

My breasts were cyst-free for 10 years after that. Then, at the beginning of the COVID pandemic, I awoke with a knot the size of a walnut in one breast. It was so tender that I thought it was a pulled muscle. Rather than try to get me in for a mammogram during the worst of lockdown, my doctor recommended applying heat to see if that would reduce the discomfort. After a few days snuggling a heating pad, the cyst went away until spring 2021, when I was 46. It showed up right in time for my annual mammogram.

I'm not alone in my experience with cystic breasts. My grandmother, mother, and sister—not to mention lots of my friends—have all had the same experience. By some estimates, 70%-90% of women will have breast cysts at some point in their lives. I feel like I'm part of a giant club, but a club that doesn't get discussed. It's as if the first rule of breast cysts is to never talk about breast cysts.

Even though I've already had breast cysts, finding a new mass in my breast or having an unusual mammogram result will never be any less alarming to me. However, learning more about breast cysts and what to expect from them has given me perspective on the experience—and the same might be true for you. Here's what you should know about breast cysts.

What exactly are breast cysts?

In simplest terms, breast cysts are harmless pockets of fluid in the breast tissue. This makes them different than cancerous tumors; tumors are solid masses, not fluid-filled.

Cysts form when fluid collects at the spot where a lobule, which produces milk during lactation, meets a milk storage duct. There are a dozen or more of these intersections in each of your breasts. "The inside of your breasts is like a bunch of grapes. Your nipple is like the central, and there are lots of small branches coming off it. The cysts form in the branches around the stem," Michelle Helms, MD, a surgeon at Cooley Dickinson Health Care in Massachusetts, tells Health.

You might get one cyst at a time or several at once. Sometimes, cysts are large enough to feel when you touch your breast, or they can cause pain or pressure in your breast. Some people get cysts and never notice them. You might only find out about them when they show up on a routine mammogram, according to Dr. Helms.

I've had both experiences. Twice, the cysts were painful knots that I could easily feel with my fingers. They were positioned close to my armpit, so moving my arm irritated them. The most recent episode were some stealth cysts that didn't cause me discomfort. I might never have known about them if I didn't have a mammogram right then. The ultrasound showed about half a dozen cysts inside both breasts. I couldn't feel them when I touched my breasts, but they were unmistakable on the ultrasound screen.

Dr. Helms says that cysts can be related to hormone levels, and they might crop up during certain parts of your menstrual cycle. You might feel them close to your period only to have them shrink after that time of the month. Other people get them at random times. It's common to have repeat episodes of breast cysts, with the cysts showing up in the same part of your breast over and over again.

Are there different types of cysts?

There are three types of cysts: simple, complicated, and complex.

Simple cysts are just sacs of fluid. They're completely benign and don't develop into anything more serious, according to the Cleveland Clinic.

Complicated cysts are sacs of fluid with specks of solid material in them. In many cases, the solid bits are dead tissue floating in the fluid. Dr. Helms says the debris isn't generally worrisome. Some doctors may suggest a fine-needle biopsy to examine the fluid more closely and make sure that the cyst is benign, per the Cleveland Clinic.

Typically, simple or complicated cysts shrink on their own and don't cause health problems. The masses can be uncomfortable—as well as a source of anxiety. But Dr. Helms says that these types of cysts arent't harmful, and they won't develop into tumors over time.

Complex cysts are more of a cause for concern. These cysts show a solid mass with fluid around it. There's potential for the solid part to be a tumor, Holly Michaelson, MD, chief of surgery at Cooley Dickinson Hospital, tells Health, so if you have one of these, you will need a biopsy to identify the cause of the solid mass.

What do breast cysts feel like?

Again, not everybody will be able to feel a cyst. Some are so small or too deep into your breast tissue to even notice them. But when they are detectable, they feel like a round or oval-shaped mass under the skin. They are usually mobile, which is to say they might slide around under your fingers when you press on them. Imagine poking an ice cube suspended in a water balloon; it will move when you press it but come back to rest in the same spot.

Despite being a sac filled with fluid, cysts can feel surprisingly firm, according to Dr. Helms. "Sometimes cysts feel soft, but they can be hard to the touch, as well," she explains. "They can also get fairly large." At their largest, they can be as big as 2 inches across, according to the Mayo Clinic.

I can confirm how big a cyst might get from personal experience. One of my cysts was about that 2-inch size. At the time, my doctor said that the size—along with how quickly it had appeared—was an indication that it was a cyst. She told me that breast cancer grows slowly, so a brand new, large mass was probably a cyst.

Since they develop in the duct system behind your nipple, cysts can appear anywhere in the breast, according to Dr. Helms. They can appear in one breast at a time or in both breasts.

Unfortunately, there is no way for you to tell if a lump found during a breast self-exam is a cyst or a tumor just by the touch. Even your doctor can't say for sure what a mass is after feeling it. The only way to be certain is by getting a mammogram or ultrasound.

Who gets breast cysts?

Breasts cysts are "exceedingly common," according to Dr. Michaelson. "If you ultrasound-scanned everyone's breasts, you'd probably find that a majority of them have cysts," she says.

Women between the ages of 30 and 55 are the most likely to have breast cysts. Men can get them, but it's not common since breast lobules and ducts don't develop in men the way they do in women. Dr. Michaelson says that she has never had a man come into her office with breast cysts.

Because cysts are related to female sex hormones, trans women on hormone replacement regimens can get cysts, too. They aren't as common for trans women as for cis women, however. Researchers theorize that trans women's shorter exposure to estrogen may reduce their chances of developing cysts.

Race, ethnicity, and lifestyle don't affect your odds of getting cysts. A family history of cysts can be a tip-off that you're prone to them. Dr. Michaelson says that cysts usually stop showing up after menopause.

What should you do if you think you have a breast cyst?

Both Dr. Michaelson and Dr. Helms say there is no way to diagnose any lump in your breast without imaging tests. If you feel a new mass, you should call your doctor to talk about it.

Your doctor will probably send you to get a diagnostic mammogram or ultrasound, like what I had to do after my last mammogram. Ultrasounds are ideal for seeing if a mass has fluid in it. If the mass in question is in fact a cyst, the ultrasound results will provide a firm diagnosis; you won't need any additional testing.

If you have a known history of cysts, Dr. Michaelson says you can wait to see if a lump shrinks before scheduling any imaging tests like a mammogram. She explains that fluctuating size is a telltale sign that a mass is a cyst. Tumors will never get any smaller, so if a mass shrinks, Dr. Michaelson says you can be sure it isn't cancer.

The "watchful waiting" approach isn't for everyone, though. People with higher risk factors for cancer, such as a personal or family history of breast cancer, should discuss their history with their doctor. Even without additional cancer risks, the idea of waiting for tests might make you anxious. If so, tell your doctor how you're feeling so you can make a treatment plan together. Your mental health is just as important as your physical health, so ask your doctor about the testing you can get to set your mind at ease.

How are breast cysts treated?

The good news about breast cysts is that you don't usually need to do anything about them. In many cases, the cysts will shrink or go away on their own and won't lead to other health issues, Dr. Michaelson says.

If a cyst is causing discomfort, try applying heat to the area, which can cause the cyst to drain on its own. My doctor told me to use a heating pad to ease pain from a particularly annoying cyst, which I found very helpful.

You can have a cyst drained if it hurts badly. The procedure for removing the fluid is done in the doctor's office. They use a needle to draw the fluid out. Dr. Helms says she only drains cysts when they cause significant discomfort. If the cyst isn't painful, the infection risk from the needle puncture outweighs the benefit of draining the cyst otherwise.

You and your doctor can discuss what kind of monitoring you need to ensure the lumps you feel aren't cause for concern. Some doctors may suggest more frequent mammograms or ultrasounds to keep an eye on changes in your breasts. And as the Mayo Clinic points out, if you have frequent cysts, it may be hard to notice new lumps that should be evaluated by a doctor. Getting regular screenings will help find the changes self-exams can miss and help you get the care you need.

Can breast cysts be prevented?

There isn't a surefire method of preventing breast cysts. Dr. Michaelson says that some people find that they have less breast pain from cysts if they reduce their caffeine intake. (Other people feel that occasional pain in the boobs is a small price to pay for the joy of drinking coffee—OK, it's me. I'm "other people.")

Dr. Michaelson says that using hormonal birth control can reduce your chances of getting cysts. However, she cautions that changes to birth control methods are a big decision with other risks involved, so discuss it with your doctor first.

My breasts have been a low-cyst zone since my scary mammogram this past spring. It's a relief not to worry about what's going on in there for the moment. But I know now that my cysts could reappear at any time. I also know that when they do, I should take the lumps seriously but I don't need to panic about this common condition.

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