What is a cyst?

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

Cysts are common and can form in any part of your body. They can vary in size and how quickly they grow.

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

What are the 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:

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

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 shown below.

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.

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

Ganglion cysts in your wrist can appear suddenly and grow quickly. They may be tender to the touch. In some people a ganglion cyst may weaken your grip.

Kidney cysts can sometimes cause back pain and large ones may cause abdominal (tummy) pain. Kidney cysts can cause blood in your urine (wee).

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

Many cysts 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 the course of your menstrual cycle.
• 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 ovarian cysts rupture, they cause sudden, severe pain in one side of your lower abdomen. Ovarian cysts can be associated with irregular periods and bleeding between periods.

What causes a cyst?

Anyone can get a cyst. Sometimes cysts can be caused by genetic conditions or tumours.

Some cysts are caused by an underlying medical condition such as:

• polycystic ovarian syndrome
• polycystic kidney disease

When should I see my doctor?

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

How are cysts 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, other tests might be needed such as:

• an x-ray
• 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.

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.

If you do need treatment, this 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.

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

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

You may need antibiotics if your cyst becomes infected.

Do not try squeezing or bursting your cyst. This can cause an infection.

Can cysts be prevented?

There is no way to prevent most cysts.

Complications of cysts

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.

Resources and support

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