What Is a Cyst?

A cyst is a closed, sac-like pocket of tissue that most commonly contains fluid, pus, or air. Most cysts are benign (not cancerous) and can appear almost anywhere in the body.

Sebaceous cyst examination
 jarabee123 / iStock / Getty Images 


Cysts are recognizable as lumps under the skin, but they can also form on internal organs where they may go unnoticed. They can appear quickly or grow slowly over time.

A cyst is different from a tumor. A tumor is an abnormal mass of swelling or tissue. It can be either benign or cancerous and can also form in any part of the body.

Your healthcare practitioner can diagnose a cyst. They are typically painless and do not require treatment. But if they are painful, become infected, affect other body structures, or are cosmetically bothersome, a healthcare provider may recommend treatment. Treatment options range from watchful waiting to surgery.

Types of Cysts

There are hundreds of types of cysts, but the most common include the following.

Epidermoid Cysts and Sebaceous Cysts

These cysts occur under the skin. They often look like flesh-colored or whitish, smooth-surfaced lumps. Epidermoid cysts can grow anywhere on the skin but are most common on the face, neck, and trunk. They are slow-growing and painless and therefore rarely need treatment.

Sebaceous cysts are a type of skin cyst but differ from epidermoid cysts. Sebaceous cysts are less common and are caused by glands that secrete oily matter that lubricate hair and skin. Trauma to the skin or blocked glands are often thought to cause these cysts. The most effective treatment is the complete surgical removal of the cyst.

Ganglion Cysts

Ganglion cysts appear along the tendons or joints on the wrists or hands but can also develop on the fingers or feet. They are rubbery and firm or soft swellings. These cysts are usually triggered by a minor injury that cause “excess joint fluid to collect in a saclike structure next to the joint.”

They are usually painless unless they are pressing on a nerve. Most of these cysts do not require treatment. But treatment is often non-surgical.

Baker's Cyst

These cysts are also called popliteal cysts. They are caused by an accumulation of trapped joint fluid found behind the knee. Baker’s cysts are often associated with arthritis, knee overuse, or knee injury, such as torn cartilage. Inflammation may also be present.

Rarely, a bulging or ruptured Baker’s cyst can cause thrombophlebitis (a process that causes a blood clot to form and block one or more inflamed veins) in the popliteal vein behind the knee. A healthcare provider can diagnose a Baker’s cyst through a physical exam.

Ovarian Cyst

Ovarian cysts can develop inside or on the exterior of an ovary. Ovarian cysts are very common in women of childbearing age and cease after menopause. Many women will have them at some point in their lives.

They often develop as a result of the hormones released during a menstrual cycle. Ovarian cysts usually don’t cause symptoms and are discovered during physical exam or ultrasound.

Breast Cysts

These cysts are noncancerous, fluid-filled sacs located inside the breast. They can range in size from small to large, causing discomfort. Hormonal changes are thought to cause breast cysts. These cysts may become painful in the days prior to your menstrual cycle.

Breast cysts do not increase your chances of cancer but can make it more challenging to find new breast lumps or determine changes that should be evaluated by a healthcare provider.

Breast cysts are diagnosed by breast exam, mammogram, and ultrasound. They can also be diagnosed and treated with fine-needle aspiration, which removes the fluid from the cyst. Hormone therapy and surgery are other treatment options that are used less frequently.

Bartholin's Gland Cysts

Bartholin’s glands help lubricate the vagina during sexual intercourse and are located in the vulva or either side of the vagina. Cysts develop in this area when a duct becomes blocked. The cause of the blockages is often unknown.

Bartholin’s gland cysts not rare, about 2% of women develop them, typically when they are in their 20s. They are often painless, though if they become infected these cysts can cause fever and painful abscesses.

If the cysts grow to be large, they can cause discomfort when walking, sitting, or during sexual intercourse. Bartholin’s gland cysts are diagnosed by physical exam or biopsy.

Cyst Symptoms

While there are many types of cysts, and they can appear anywhere on the body, they share some common symptoms:

  • Lump under the skin
  • Pain and pressure
  • Discomfort

It is common for cysts to be asymptomatic, especially if they are found on an internal organ, such as on the liver, kidney, or ovary, where they are not readily seen.


Common causes of cysts include:

  • Injury that breaks a vessel
  • Blocked ducts that cause fluid buildup
  • Hormones, such as those related to female-specific cysts (breast and ovarian), that may make cysts develop and grow

When to Seek Treatment

Most cysts are harmless and may go away without treatment. However, if the cyst is causing pain, discomfort, fever, becomes infected, or affects other structures, you may need to seek medical care. Infection is a major concern because it can lead to more serious problems such as sepsis.


A healthcare provider or another healthcare professional can diagnose a cyst. They will likely start with a physical exam and examine the shape and size of the cyst. The provider may ask questions like how long you have had the cyst, how fast it is growing, and if it is painful.

From there, your healthcare provider may use additional diagnostic tools such as:

  • Ultrasound: An ultrasound helps determine if the cyst is filled with fluid or is solid.
  • X-ray: Although cysts do not show up on X-ray, they may help rule out more serious conditions that may mimic symptoms of a cyst that cause pain and discomfort.
  • Magnetic resonance imaging (MRI): An MRI can offer very clear, detailed pictures of the part of the body in question.


Treatment options depend on the type and size of the cyst and also what symptoms it is causing you. If a cyst is infected, your healthcare provider will prescribe medication to treat it. Infections are important to address. If an infected cyst ruptures it can lead to more serious issues such as sepsis.

Often no treatment is necessary for a cyst. The following are options, however, if your healthcare provider recommends taking action:

  • Injections and medication: A healthcare provider can inject medication to shrink or eliminate cysts. However, it is not uncommon for cyst recurrence with this type of treatment.
  • Hormone treatment: Some female-specific cysts are hormone-driven and may be treated with birth control pills or other hormone therapy. The thought is that these cysts will shrink or disappear by pausing the hormones associated with the menstrual cycle.
  • Surgery: Surgery removes or drains the cyst. Surgery can permanently eliminate the cyst and the chance of recurrence.

A Word From Verywell

 Cysts are common but they are normally not a big cause for concern. Sometimes cysts will go away on their own but if not, you have options to treat them. Contact your healthcare provider for more information.

10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Cherie Berkley, MS
Cherie Berkley is an award-winning journalist and multimedia storyteller covering health features for Verywell.