What is a cyst?

A cyst is a sac that forms in your skin or body. It’s filled with fluid or semi-solid material. Most cysts are benign (not cancerous).

Cysts are common and can form in any part of your body. Cysts vary in size and can grow quickly or slowly.

Cysts are different from abscesses, which are collections of pus from an infection.

What causes a cyst?

Anyone can get a cyst. Sometimes the cause is not known.

The cause of cysts can be:

• build-up of fluid
• tendon injury
• genetic conditions
• tumours
• hormone changes

Sometimes cysts are due to an underlying medical condition such as:

• polycystic ovarian syndrome
• polycystic kidney disease

Types of cysts

There are hundreds of different types of cysts. These form in different parts of your body.

Some of the common types are:

• acne epidermoid cysts and sebaceous cysts — on your skin
• ovarian cysts
• breast cysts
• kidney or lung cysts
• ganglion cysts — in your wrists, fingers or feet
• Baker’s cyst — behind your knee
• Bartholin’s cysts — on your vulva

What are the symptoms of cysts?

Your symptoms will depend on the type of cyst you have and where it is. Some common symptoms of different cysts are listed below.

Skin cysts are usually small and don’t cause pain. If they become inflamed or burst, they might be red, swollen and tender.

Most ovarian cysts are harmless. However, they can rupture (burst), which causes sudden severe pain in one side of your lower abdomen (tummy). People with ovarian cysts can get irregular periods and bleeding between periods.

Kidney cysts are usually harmless, but can sometimes cause back pain and large ones may cause abdominal (tummy) pain. Kidney cysts can cause blood in your urine (wee), but often you will have no symptoms of a kidney cyst.

Ganglion cysts in your wrist can appear suddenly and grow quickly. They may be tender to touch. Rarely, you may notice a change in sensation in your hand or fingers.

A Baker's cyst may feel like a hard-boiled egg when you bend your knee. Your knee joint may also feel swollen and tight. If your cyst bursts, you may feel pain in the back of your knee or down your leg. They are also called popliteal cysts.

Bartholin's gland cysts may cause a recurring, tender swelling on either side of the entrance to the vagina. Sometimes, they can become infected.

Types of cysts that do not usually cause symptoms

Cysts often don’t cause any symptoms. You may only become aware of them when they burst or when they’re found through other tests. Some examples of these are given below.

Most breast cysts do not cause any symptoms. Others can be tender to touch. A breast cyst may change size during your menstrual cycle.

You may have an ovarian cyst with no symptoms.

Kidney cysts are often only discovered when an imaging test is done for another reason.

Nabothian cysts in your cervix usually have no symptoms.

When should I see my doctor?

If you notice a growth or swelling anywhere on your body, you should see a doctor.

When should I seek urgent medical help?

If you have symptoms of a cyst and have a fever (temperature above 38ºC) you should see a doctor as soon as possible or go to your nearest emergency department.

How is a cyst diagnosed?

Your doctor will ask you some questions about your cyst. These might include:

• when you first noticed your cyst
• whether its size has changed
• how quickly it grew
• if it’s painful

Depending on the type of cyst, an imaging test might be needed, such as:

• an ultrasound
• a CT scan

Your doctor may need to do a biopsy (take a small sample of tissue from your cyst, usually with a needle) to help diagnose it.

Your doctor can check if a cyst or lump is benign or a cancer.

How are cysts treated?

If your cyst isn’t causing symptoms, you may not need any treatment. In fact, many cysts disappear without needing treatment.

Self-care at home

Some cysts can be treated with ice packs or warm compresses depending on their location.

Do not squeeze or burst your cyst. This can cause an infection.

Other treatment options

If your cyst needs medical treatment, it will depend on:

• the type of cyst you have
• where it is on your body
• how painful it is

Your doctor may drain large, painful cysts with a needle. But sometimes cysts can come back after draining. Surgically removing a cyst can make it less likely to come back.

If you have an underlying medical condition that is causing your cysts, your doctor may want to monitor your condition.

What are the complications of cysts?

Cysts can become infected or burst. You may need antibiotics if your cyst becomes infected.

Large cysts can press on nerves or other parts of your body and cause pain.

Draining or surgically removing a cyst usually has few complications or side effects.

Your doctor will talk with you about what to expect if you have a cyst drained. Your cyst may refill and come back.

You may become anxious and worry that your cyst is cancer.

If you have polycystic ovary syndrome (POCS) you could have a higher chance of cardiovascular (heart and circulation) problems or metabolic problems, such as diabetes.

Can cysts be prevented?

There is no way to prevent most cysts.

Resources and support

You can find out more about different types of cysts through these resources.

• Learn about cysts under the skin at the Community help pages of The Australasian College of Dermatologists website.
• Learn about Baker’s cysts at Musculoskeletal Health Australia.
• Learn about breast cysts at the Royal Women's Hospital website. They also have fact sheets in a range of languages other than English.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with you 24 hours a day, 7 days a week.