A cyst is a sac-like pocket of membranous tissue that contains fluid, air, or other substances. Cysts can grow almost anywhere in your body or under your skin.

There are many types of cysts. Most cysts are benign, or noncancerous.

Whether a cyst needs treatment depends on a number of factors, including:

  • the type of cyst
  • the location of the cyst
  • if the cyst is causing pain or discomfort
  • whether the cyst is inflamed or infected

If you’re not sure if you have a skin condition, you can take a picture and send it to an online dermatologist.

Cysts can vary in appearance depending on their type and location. Here are 11 types of cysts.

Warning: Graphic images ahead.

Epidermoid cyst

close-up of an epidermoid cyst on the back of the neckShare on Pinterest
Photography courtesy of Steven Fruitsmaak/Wikimedia
  • An epidermoid cyst is a small, slow growing, benign cyst most commonly found on the face, head, neck, back, or genitals.
  • It’s usually caused by a buildup of keratin under the skin.
  • It looks like a skin-colored, tan, or yellowish bump filled with thick material.
  • It may become swollen, red, or painful if it’s inflamed or infected.

Read more about epidermoid cysts.

Sebaceous cyst

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Photography courtesy of Klaus D. Peter, Wiehl, Germany/Wikimedia Commons
  • A sebaceous cyst is found on the face, neck, or torso.
  • It’s usually caused by trauma or damage to the sebaceous glands, such as from cuts or surgical wounds.
  • A large cyst may cause pressure and pain.
  • It’s noncancerous and very slow growing.

Read more about sebaceous cysts.

Breast cyst

ultrasound image of a breast cystShare on Pinterest
Photography courtesy of Nevit Dilmen/Wikimedia Commons
  • Most breast lumps (such as cysts) are noncancerous, but there are many possible causes for a lump in your breast.
  • Instead of performing a breast self-exam, it’s important to be familiar with how your breasts typically feel so you’re aware of changes. This way, you’re more likely to notice changes right away.
  • You should make an appointment to see a healthcare professional if:
    • you discover a new lump
    • an area of your breast is noticeably different than the rest
    • a lump changes or grows larger
    • you notice unexpected discharge from the nipple
    • you have an inverted nipple, and it wasn’t always inverted

Read more about breast lumps.

Ganglion cyst

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LALIDA BOONMEE/Shutterstock
  • A ganglion cyst is a round, gel-filled lump of tissue that usually appears along tendons or joints, especially in the hands, wrists, ankles, and feet.
  • Fluid accumulation can occur due to injury, trauma, or overuse, but often the cause is unknown.
  • A ganglion cyst is common, harmless, and doesn’t cause pain or problems unless it grows and puts pressure on other structures.

Read more about ganglion cysts.

Pilonidal cyst

close-up of a pilonidal cyst in the cleft of the buttocksShare on Pinterest
Alan Nissa/Shutterstock
  • A pilonidal cyst is a common skin condition that forms in the cleft at the top of the buttocks. It typically occurs after puberty.
  • It’s believed to be caused by a combination of changing hormones, hair growth, and friction from clothes or from spending a long time sitting.
  • It consists of a small hole or tunnel in the skin that may become infected and fill with fluid or pus.
  • Signs of an infection include:
    • pain when sitting or standing
    • red or sore skin around the area
    • pus or blood draining from the abscess, causing a foul odor
    • swelling of the cyst
    • hair protruding from the lesion

Read more about pilonidal cysts.

Ovarian cyst

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Photography courtesy of Euthman/Wikimedia Commons
  • Ovarian cysts are fluid-filled sacs that develop on one or both of the ovaries.
  • They may develop as a normal part of the reproductive cycle or be pathologic.
  • They may be asymptomatic or painful.
  • Symptoms include:
    • abdominal bloating or swelling
    • painful bowel movements
    • pelvic pain before or during the menstrual cycle
    • painful intercourse
    • pain in the lower back or thighs
    • breast tenderness
    • nausea
    • vomiting
  • Severe symptoms such as sudden, sharp pelvic pain, fever, faintness, or dizziness are signs of cyst rupture or ovarian torsion.

Read more about ovarian cysts.

Baker’s (popliteal) cyst

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Photography courtesy of Hellerhoff/Wikimedia Commons
  • A Baker’s cyst is a fluid-filled swelling that causes a lump at the back of the knee.
  • This condition is due to a problem that affects the knee joint, such as arthritis, inflammation from repetitive stress, or a cartilage injury.
  • Symptoms include:
    • mild to severe pain
    • tightness
    • limited range of motion
    • swelling behind the knee
    • bruising on the knee and calf
    • rupturing of the cyst
  • A Baker’s cyst often doesn’t need treatment and will go away on its own.

Read more about Baker’s cysts.

Pilar cyst

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Photography by DermNet New Zealand
  • A pilar cyst is a noncancerous, skin-colored, round bump that develops under the surface of the skin. It’s usually located on the scalp.
  • This type of cyst is caused by protein buildup in a hair follicle.
  • It’s painless, firm, smooth, and slow growing.

Read more about pilar cysts.

Mucous cyst

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Hercules Robinson/Alamy Stock Photo
  • A mucous cyst is a fluid-filled swelling that occurs on the lip or the mouth.
  • It develops when the mouth’s salivary glands become plugged with mucus.
  • It’s commonly caused by trauma to the oral cavity, such as lip biting, piercings, and salivary gland disruption.
  • Mucous cysts are small, soft nodules that are pinkish or bluish.

Read more about mucous cysts.

Branchial cleft cyst

large branchial cleft cyst on the right side of the neck of a man
Photography by BigBill58/Wikimedia Commons
  • A branchial cleft cyst is a type of developmental irregularity in which a lump develops on one or both sides of the neck or below the collarbone.
  • It occurs during embryonic development when tissues in the neck and collarbone, or branchial cleft, develop differently.
  • In most cases, a branchial cleft cyst isn’t dangerous. However, it may cause skin irritation, skin infection, or — in very rare adult cases — cancer.
  • Symptoms in children include:
    • a dimple, lump, or skin tag on the neck, upper shoulder, or slightly below the collarbone
    • fluid draining from the neck
  • Children and adults may experience swelling or tenderness that usually occurs with an upper respiratory infection.

Read more about branchial cleft cysts.

Perineural (Tarlov) cyst

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Photography by Malisan.mrosa/Wikimedia Commons
  • A perineural cyst is a fluid-filled sac that forms on the spine.
  • Causes are unknown, but it may result from back trauma. Types of trauma associated with this cyst include falls, injuries, and heavy exertion.
  • Symptoms are rare. In these cases, it may cause pain in the lower back, buttocks, or legs.

Read more about perineural cysts.

A pseudocyst shares some of the characteristics of a cyst, but the bump doesn’t have its own lining. Here are three types of pseudocysts.

Folliculitis (ingrown hair cyst)

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FCG/Shutterstock
  • Folliculitis describes a category of skin conditions that cause inflammation in a hair follicle and are usually infectious.
  • Ingrown hair cysts are a type of folliculitis. They start off as hairs that grow down or sideways instead of out, becoming ingrown.
  • Folliculitis is common among people who shave, wax, or use other methods to remove hair.
  • Folliculitis appears as pimple-like bumps under the skin that may be red, white, or yellow, with or without a central visible hair.
  • Bumps that appear near an ingrown hair are more likely to be pseudofolliculitis barbae (razor bumps) than ingrown hair cysts.
  • Ingrown hair cysts may become infected and appear red, warm, and tender to the touch.

Read more about ingrown hair cysts.

Chalazion

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Manish thapaa/Shutterstock
  • A chalazion is a small, usually painless lump or swelling on your upper or lower eyelid.
  • It’s caused by a blocked meibomian gland. The meibomian gland is a type of oil gland.
  • It may be red, swollen, and painful if an infection is present.

Read more about chalazia.

Cystic acne

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ideation90/Getty Images
  • Cystic acne is the most severe type of acne, and it develops when bumps form deep underneath your skin.
  • It can result from a combination of hormone changes, bacteria, oil, and dry skin cells that get trapped in your pores.
  • Cystic acne may occur on the face, chest, neck, back, and arms. Large, painful, pus-filled bumps and nodules may form, rupture, and leave scars. They may appear red or skin-colored, depending on your skin tone.

Read more about cystic acne.

A cyst can appear as a bump on your skin. It may also feel like a small lump if it’s growing just under your skin.

Some cysts grow deep inside your body where you can’t feel them. However, they may cause or be related to other symptoms.

For example, ovarian cysts, such as those that result from polycystic ovary syndrome (PCOS), may cause problems with ovarian and reproductive function. Polycystic kidney disease (PKD), which causes cysts to form in the kidney, can adversely affect kidney function.

Cysts usually grow slowly and have a smooth surface. They can be tiny or very large.

Most cysts aren’t painful. They usually don’t cause problems unless they’re:

  • infected
  • very large
  • impinging on a nerve or blood vessel
  • growing in a sensitive area
  • affecting the function of an organ

Cysts and pseudocysts form for different reasons. They can be caused by:

The exact cause depends on the type of cyst or pseudocyst.

There are hundreds of different types of cysts and pseudocysts. They can grow almost anywhere in your body.

Some cysts occur as part of another condition, such as PCOS or PKD. Some of the more common types of cysts and pseudocysts include the following:

Epidermoid cyst

These are small, benign bumps filled with the protein keratin. If you have trauma around a hair follicle within the skin, an epidermoid cyst may occur.

If part of the top layer of your skin, called the epidermis, grows deeper instead of moving outward toward the surface to eventually be shed off, an epidermoid cyst will have a chance to form.

In rare cases, epidermoid cysts can be caused by an inherited condition called Gardner’s syndrome.

Sebaceous cyst

Sebaceous cysts fill with sebum and are less common than epidermoid cysts. They often form within sebaceous glands, which are part of the skin and hair follicles.

Sebaceous glands make oil for your skin and hair. Ruptured or blocked sebaceous glands can lead to sebaceous cysts.

Breast cyst

Benign cysts can develop in your breasts when fluid collects near your breast glands. They can cause pain or tenderness in the affected area.

They commonly occur in female breast tissue in those in their 30s and 40s.

Ganglion cyst

These benign cysts usually form near the joint areas of your wrist or hand. However, they can also develop in your feet or ankle areas. The reason they form isn’t known.

Ganglion cysts tend to occur along a tendon sheath near a joint. They’re more common in women than in men.

Pilonidal cyst

Pilonidal cysts form near the top part of the buttocks. They’re usually filled with skin debris, body oils, hair, and other matter.

They occur more often in men than in women. They can develop when loose hairs become embedded in your skin.

Chronic infections in these cysts might increase your risk of a type of skin cancer called squamous cell carcinoma. If you have these chronic infections, learn the symptoms of skin cancer so it can be treated early.

Ovarian cyst

Ovarian cysts often form when the follicle that normally releases an egg doesn’t open. This causes fluid to build up and form a cyst.

Another common type of ovarian cyst occurs after the follicle releases the egg and improperly recloses and collects fluid.

Ovarian cysts occur most often in those of menstrual age. They’re usually found during pelvic exams.

Ovarian cysts are associated with an increased risk of cancer when they occur after menopause.

Baker’s (popliteal) cyst

A Baker’s cyst, also known as a popliteal cyst, is a fluid-filled cyst that forms at the back of the knee.

These cysts are usually caused by problems with the knee, such as injury or arthritis. Mobility can be limited and painful with a Baker’s cyst.

Physical therapy, fluid draining, and medication can all be used to help treat a Baker’s cyst.

Pilar cyst

Pilar cysts are skin-colored, benign lumps that form on the skin’s surface. They’re not cancerous, but they can grow to a size that can be uncomfortable.

Removal is typically not necessary, but they can be removed for cosmetic purposes.

Mucous cyst

A mucous cyst is a fluid-filled lump that forms on the lip or around the mouth when the salivary glands become plugged with mucus. The most common causes of mucous cysts include:

Mucous cysts will often go away on their own. However, if you have recurring or frequent mucous cysts, you may need medical treatment.

Branchial cleft cyst

Branchial cleft cysts are a type of developmental irregularity that causes a lump on an infant’s neck or below the collarbone. This cyst can look like a large skin tag.

Healthcare professionals usually recommend surgical removal to prevent future infection.

Perineural (Tarlov) cyst

A perineural cyst is a fluid-filled sac that forms on the spine.

Most people won’t have symptoms, so they won’t need treatment. If you do have symptoms, draining the fluid can help to relieve them.

Chalazion

Chalazia are benign pseudocysts that occur on your eyelids when the duct of the meibomian gland, an oil gland, is blocked.

These pseudocysts can cause tenderness, blurred vision, and painful swelling. If they get too big, they can cause vision problems.

Cystic acne

Cystic acne results from a combination of bacteria, oil, and dead skin clogging the pores. It’s the most severe type of acne, but it usually improves with age.

Cystic acne can look like large, pus-filled boils on the skin. It can also be painful to the touch.

If you believe you may have cystic acne, your dermatologist can prescribe medications to help treat it.

Folliculitis (ingrown hair cyst)

Folliculitis is an inflammatory and usually infectious condition. It can form when a hair grows into the skin and a pseudocyst forms near it.

These pseudocysts are often seen in people who use hair removal methods like shaving or waxing. Ingrown hair cysts are an example of folliculitis.

While ingrown hair cysts are possible, if you have bumps that appear near ingrown hairs, there’s a good chance that they’re actually razor bumps instead.

Razor bumps are also known as pseudofolliculitis barbae, which is a type of pseudofolliculitis. Unlike folliculitis, pseudofolliculitis isn’t usually infectious.

Most of the time, medical care isn’t needed to treat folliculitis or razor bumps. However, see a healthcare professional if you suspect the ingrown hair cyst or razor bump is infected.

Schedule an appointment with a healthcare professional if your cyst becomes very painful or inflamed. This could be a sign of a rupture or an infection.

They should check your cyst even if it isn’t causing any pain or other problems. Differences in these growths can be a symptom of cancer. A healthcare professional may want to remove a tissue sample for testing.

You should never try to squeeze or pop a cyst or pseudocyst yourself. This can lead to infection.

In some cases, they improve on their own. Putting a warm compress on a cyst can speed up the healing process by helping it drain.

In other cases, medical care is required.

Medical care

Common methods of medical treatment for cysts include a healthcare professional:

  • using a needle to drain fluids and other matter from the cyst
  • giving you medications, such as a corticosteroid injection, to reduce inflammation in the cyst
  • performing surgical removal of the cyst, which may be done if draining doesn’t work or if you have an internal cyst that’s hard to reach and requires treatment

If you’re concerned about your cyst and don’t have an established relationship with a healthcare professional, you can view doctors in your area through the Healthline FindCare tool.

Benign cysts and pseudocysts usually don’t cause long-term problems. Sometimes they even go away on their own.

Cysts can refill after being drained. If you have a cyst that continues to refill, you may want to consider having it surgically removed.

If you have cancerous cysts, your healthcare professional will discuss treatment with you. The outlook will vary depending on the type of cancer involved.

Most types of cysts and pseudocysts can’t be prevented. However, there are a few exceptions.

Those prone to ovarian cysts may be able to prevent new cysts from forming by using hormonal contraceptives.

You can prevent pilonidal cysts from forming by keeping the skin in the affected area clean and dry. Getting up every so often instead of sitting for a long time can also help prevent these cysts.

Cleaning your eyelid near the eyelash line with a gentle cleanser can help keep the oil ducts from becoming blocked. This may help prevent chalazia.

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