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Medically reviewed by Last updated on Mar 9, 2022.

What is a cyst?

Harvard Health Publishing

Cysts are sacs or capsules that form in the skin or inside the body. They may contain fluid or semisolid material. Although cysts can appear anywhere in the body, most frequently they live in the skin, ovaries, breasts or kidneys. Most cysts are not cancerous.  

Common locations of cysts include: 

  • Skin — Two types of cysts commonly occur underneath the skin, epidermoid cysts and sebaceous cysts. Both usually appear as flesh-colored or whitish-yellow smooth-surfaced lumps. Epidermoid cysts form when surface skin cells move deeper into the skin and multiply. These cells form the wall of the cyst and secrete a soft, yellowish substance called keratin, which fills the cyst. Sebaceous cysts form inside glands that secrete an oily substance called sebum. When normal gland secretions become trapped, they can develop into a pouch filled with a thick, cheese-like substance. Common sites include the back of the neck, the upper back and the scalp.  
  • Wrists — Ganglion cysts develop as rubbery or soft swellings, usually in response to a minor injury that triggers excess joint fluid to collect in a saclike structure next to the joint. Ganglion cysts also can occur on the fingers or feet.  
  • Knees — A Baker's cyst is a pouch of joint fluid that collects behind the bend of the knee. Because of its location, this cyst may cause the knee joint to feel swollen or tight. In most people, Baker's cysts are linked to arthritis or knee injury.  

  • Ovaries — An ovarian follicle that doesn't release its egg may form a cyst on the ovary. These cysts are not harmful and usually disappear after two to three months. 

  • Breasts — Breast lumps may be either cystic or solid. Breast cysts are almost always benign (non-cancerous).

  • Vagina — Bartholin's gland cysts may develop in one of the Bartholin's glands, which lie just inside the vaginal canal and produce a protective, lubricating fluid. The buildup of secretions or infections inside one of the Bartholin's glands can cause the gland to swell and form a cyst.  

  • Cervix — Nabothian cysts develop when one of the mucous glands of the cervix becomes obstructed.  

  • Kidneys — Solitary cysts (also known as simple cysts) are the most common type. They appear as fluid-filled pouches and usually do not cause any symptoms. About 25% of Americans older than age 50 have this type of cyst. Some people inherit the tendency to develop many kidney cysts, a condition called polycystic kidney disease, which often causes high blood pressure and can lead to kidney failure. 

Symptoms of a cyst

Cysts can cause a wide range of symptoms, depending on the type of cyst and its location. Here are some common symptoms grouped by location: 

  • Skin — Typically slow growing and painless, skin cysts are usually small, although some can grow to the size of golf balls. They do not cause pain unless they rupture or become inflamed. In these cases, there will be redness, swelling and tenderness.  
  • Wrists — Ganglion cysts can appear suddenly and grow quickly. They usually are about the size of a dime, and may be tender to the touch. In some cases, a ganglion cyst may weaken a person's grip or make it painful.  
  • Knees — Baker's cyst may feel like a hard-boiled egg when the patient bends the knee. The knee joint may feel swollen and tight. If a cyst breaks open, it can cause pain in the back of the knee or down the leg. If a cyst is large enough, it can lead to swelling in the leg and foot.  
  • Ovaries — When ovarian cysts rupture, they cause sudden, severe pain in one side of the lower abdomen or upper pelvis. Ovarian cysts are associated with menstrual spotting and irregular menstruation.  
  • Breasts — Most breast cysts do not cause any symptoms. Others are tender to the touch. Cysts may change in size and sensitivity during the course of a menstrual cycle.  
  • Vagina — Bartholin's gland cysts may cause a recurring, tender swelling on either side of the vaginal entrance. Sometimes, they can become infected; causing pain, and occasionally pus may drain from them.  
  • Cervix — Nabothian cysts usually have no symptoms.  
  • Kidneys — Usually, kidney cysts are discovered only when a radiology test is done for another reason. Cysts can sometimes cause back pain. If they grow large enough, they can trigger abdominal pain. Cysts can cause bloody urine. Polycystic kidney disease is an inherited disorder that can lead to kidney failure. 

Diagnosing a cyst

In cases of visible cysts, such as those in the skin and wrists, your doctor will ask you when you first noticed the cyst, how quickly it grew, whether its size has changed, and if it is painful. During a physical exam, your doctor will look for redness and tenderness and will examine the size and shape of a suspected cyst. Often, this visual inspection is all that's needed.  

Depending on the type of cyst, other tests may be necessary:  

  • Knees — A Baker's cyst can almost always be diagnosed by looking at it. The cyst is not visible on standard X-rays, although X-rays can confirm the presence of osteoarthritis, which is associated with these cysts. Occasionally, an ultrasound is done if swelling extends into the back of the calf to be certain that the leg swelling is caused by the cyst and not a blood clot in the leg. Rarely, magnetic resonance imaging is necessary.  
  • Ovaries — Ultrasound scans locate the cyst and tell if it is filled with fluid. Depending on the cyst's characteristics and a person's age, a repeat ultrasound may be done in a few months to see if the cyst goes away.  
  • Breasts — A breast lump discovered by you or your doctor may be a cyst or solid tissue. Depending on your age, personal medical history and family medical history, your doctor may:  
    • Repeat the breast examination after you have completed your next menstrual period.  
    • Place a thin needle into the lump. If fluid can be drained, the lump is a cyst. Your doctor may send the fluid to a laboratory to be examined under a microscope.  
    • Order a breast ultrasound that can determine if the lump is solid or fluid-filled.  
    • Order a mammogram to look for any suspicious abnormalities before deciding if a biopsy is necessary. A biopsy is the removal of a tissue sample for laboratory testing.  
  • Vagina — During a gynecological exam, your doctor will look for a tender lump, a Bartholin's gland cyst, near the opening of the vagina. Any redness, swelling, tenderness or pus suggests an infection.  
  • Cervix — During a gynecological exam, your doctor may see fluid-filled Nabothian cysts on your cervix.  
  • Kidneys — Ultrasound or computed tomography (CT) scans can detect kidney cysts. 

Expected duration of a cyst

Many cysts, such as wrist or ovarian cysts, go away on their own. Others, such as skin cysts, grow slowly in size and may go away on their own or may need to be drained if they produce symptoms or become inflamed. Cysts in the cervix may disappear after a woman gives birth. Kidney cysts usually do not go away. 

Preventing a cyst

There is no way to prevent most cysts.

Treating a cyst

The need for treatment and the type of treatment depend on the type of cyst, its location and your symptoms. If the cyst does not cause symptoms or pose a health threat, you probably will not need any treatment. In other cases, one of the following treatments may be recommended: 

  • Skin — For a large or inflamed cyst, your doctor may recommend draining the cyst. Skin cysts often have a surrounding capsule that also needs to be removed to prevent the cyst from recurring.  
  • Wrists — Painful ganglion cysts may be treated with ice packs applied directly to the wrist and with pain relievers, such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin and others). If you don't like the way the cyst looks, or if you experience pain or weakness in your grip, your doctor can use a needle to remove the fluid from the cyst. The cyst can become bigger again. In some cases, surgery may be done to remove the cyst.  
  • When To Call A ProfessionalKnees — Because Baker's cysts are most commonly associated with arthritis of the knee, treatment is directed at the arthritis. If the cyst is very large, your doctor can use a needle to remove the fluid from the cyst and/or inject corticosteroid medication into the cyst or knee.  

  • Ovaries — Most ovarian cysts are simple cysts that don't require specific treatment. Expanding or ruptured cysts that cause pelvic pain are treated with oral pain relievers. Cysts that have a more complex appearance on ultrasound or CT scan may require additional evaluation such as direct visualization with laparoscopy and possible biopsy. A woman with an ovarian cyst that is most likely benign but has a slightly unusual appearance may be asked to repeat the ultrasound in one to two months.  

  • Breasts — If you have a fluid-filled lump, your doctor may insert a needle into the cyst and remove the fluid. This makes the cyst smaller and allows the doctor to send a sample of the fluid to the lab for testing. If the lump is not fluid-filled, your doctor will use your age, mammogram results, risk factors and character of the lump to decide whether you should have a surgical biopsy of the lump or have it removed.  

  • Vagina — Your doctor may tell you to apply warm, wet compresses (such as a warm washcloth) to the area, and to take ibuprofen or acetaminophen to relieve any pain. If a rash or fever develops or if pus drains from the cyst, your doctor may make a small incision in the cyst to allow it to drain and may prescribe antibiotics.  

  • Cervix — Usually, Nabothian cysts do not need to be treated.  

  • Kidneys — Fluid-filled cysts do not require treatment. If the cyst causes symptoms, your doctor can drain it with a needle under ultrasound or CT scan guidance or remove it through laparoscopic surgery (surgery through small incisions). Your doctor may send a sample of the fluid to a laboratory for testing. If you have polycystic kidney disease, your doctor will recommend regular checkups to monitor your kidney function. People who develop kidney failure from inherited cysts need dialysis or a kidney transplant. 

When To Call A Professional

Make an appointment to see a doctor whenever you notice an abnormal growth or swelling anywhere on your body. If you think you may have an inflamed skin cyst or a Bartholin's gland cyst in your vagina, use warm compresses and acetaminophen or ibuprofen to reduce inflammation until you can see your doctor. Sometimes, these early steps are enough to treat the problem. If you have diabetes call your doctor the same day you notice signs of infection because you are at risk of having the infection spread.  

If you are a woman, contact your doctor immediately if you experience sharp, sudden pain in your lower abdomen or upper pelvis or you have abdominal pain with a fever. You may have a ruptured ovarian cyst, but it also could be appendicitis. New breast lumps should be evaluated promptly by a doctor.


The prognosis for the vast majority of cysts is excellent. Many cysts do not cause any symptoms and go away on their own. Cysts can come back. Draining or surgically removing cysts usually has no complications or side effects.  

In rare cases in which a cyst is next to or inside a cancerous tissue, the prognosis depends on the type of cancer and whether it has spread.

Additional Info

National Institutes of Health (NIH)

Further information

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