Cyst

A cyst is a closed sac that forms within the skin or another part of the body. It may contain fluid, air, pus, or thicker material. Cysts can develop almost anywhere, including the skin, breasts, ovaries, kidneys, joints, bones, and brain.

“Cyst” describes the structure rather than one specific disease. A small skin cyst and a cyst inside an organ may have very different causes, symptoms, and treatments. A scan report may also use the term cystic lesion, meaning an area that looks fluid-filled. Further assessment may be needed to identify exactly what it is.

Most cysts are non-cancerous, or benign. However, a lump should not be assumed to be a cyst without assessment. Solid growths can sometimes feel or look similar, and some tumours contain cyst-like areas.

Many cysts cause no problems and are found by chance. Others matter because they become inflamed, get infected, grow, rupture, or press on nearby tissues. The location, appearance, size, and effect on your body are usually more important than the word “cyst” alone.

A cyst near the skin may feel like a smooth, round lump. It may move slightly when touched. Some have a small dark opening on the surface. An uncomplicated skin cyst is often painless.

Possible symptoms include:

• A visible or noticeable lump
• Swelling or a feeling of fullness
• Tenderness, redness, or warmth if inflamed
• Drainage of thick, sometimes unpleasant-smelling material
• Pressure or discomfort in the affected area

Cysts deeper in the body may not be noticeable from the outside. Their symptoms reflect where they are. For example, a cyst may affect joint movement, cause pelvic or abdominal discomfort, or interfere with the normal work of an organ.

Symptoms do not reliably show whether a lump is harmless. A rapidly growing, hard, fixed, irregular, or unexplained lump needs medical assessment, even if it does not hurt.

A cyst forms when fluid, cells, or other material becomes enclosed within tissue. The process differs between cyst types.

Common mechanisms include:

• A blocked gland, duct, or hair follicle
• Inflammation or infection
• Injury that pushes surface cells into deeper tissue
• Changes during normal hormonal cycles
• Abnormal development before birth
• An inherited condition affecting organs or tissues
• A parasite, although this is uncommon in many countries
• No identifiable cause

An epidermoid cyst, a common type found under the skin, often contains keratin. Keratin is a protein normally present in skin, hair, and nails. It collects inside the cyst when skin cells become trapped below the surface.

Risk factors are also specific to the type. Previous skin injury or surgery can contribute to some skin cysts. Hormonal and reproductive factors may influence certain ovarian or breast cysts. Some kidney and liver cysts are linked to inherited conditions, while many simple cysts appear without a clear trigger.

A cyst is not usually caused by poor hygiene. Touching a cyst does not normally spread it to another person, although an infection affecting the area may sometimes be contagious.

A healthcare professional may be able to identify a typical skin cyst by asking about its history and examining it. They may check its size, texture, movement, tenderness, and effect on the surrounding skin.

A deeper lump or a cyst inside the body may require imaging. The test used depends on its location:

• Ultrasound uses sound waves to show whether an area is mainly fluid-filled or solid.
• X-rays or mammography may help assess cysts in certain tissues.
• CT scans create detailed cross-sectional images.
• MRI scans use magnets to show soft tissues in greater detail.

Imaging can suggest that an area is a simple cyst. A simple cyst usually has thin, smooth walls and fluid inside. A complex cyst may contain thicker walls, internal divisions, solid-looking areas, or blood. “Complex” does not automatically mean cancer, but it may lead to closer assessment.

Sometimes fluid is removed with a needle, a procedure called aspiration. This may help diagnose or relieve certain cysts. A sample of the cyst wall or nearby tissue may be examined under a microscope when the diagnosis remains uncertain or the cyst has been removed.

Not every cyst needs every test. Its location, examination findings, scan appearance, and symptoms guide the next steps.

A small cyst that is not painful, changing, or affecting normal activities may only need observation. Follow-up may involve checking for changes yourself, having a repeat examination, or undergoing another scan at a planned interval.

Do not squeeze, puncture, or try to drain a cyst at home. This can cause infection, bleeding, scarring, or inflammation. It may also make later assessment more difficult.

Treatment options include:

• Drainage: A clinician may release or withdraw the contents. This can reduce pressure, but the cyst may return if its wall remains.
• Medication: Pain relief or treatment for inflammation may be used when appropriate. Antibiotics like amoxicillin or doxycycline may be needed for a bacterial infection, but they do not remove an uninfected cyst.
• Injection treatment: Certain inflamed cysts may be treated with medicine injected into the area.
• Surgical removal: Removing the whole cyst, including its wall, can lower the chance of that individual cyst returning. This may leave a scar.
• Specialist procedures: Cysts in organs, joints, bones, or the brain may need monitoring, image-guided treatment, keyhole surgery, or open surgery.

An inflamed cyst is not always infected. A clinician may delay complete removal until inflammation has settled because the cyst wall can be harder to remove intact at that time.

Treatment decisions consider more than size. Pain, repeated inflammation, uncertain diagnosis, cosmetic concerns, pressure on nearby structures, and changes on imaging may all matter.

Many cysts remain stable and never cause complications. Possible problems include:

• Inflammation, pain, or swelling
• Bacterial infection and abscess formation
• Rupture, which can irritate nearby tissue
• Bleeding into the cyst
• Scarring after inflammation or treatment
• Return of the cyst after drainage or incomplete removal
• Pressure on a nerve, blood vessel, organ, or duct

A cyst in an ovary can occasionally twist the ovary or rupture. A cyst in the brain or spinal area can cause neurological symptoms if it affects nearby structures. These are location-specific problems and do not apply to ordinary skin cysts.

Most cysts do not become cancerous. However, a growth that appears cyst-like may sometimes have another diagnosis, which is why unexplained or changing lumps should be assessed.

Many cysts cannot be prevented. This is especially true when the cause is inherited, developmental, hormonal, or unknown.

Avoiding unnecessary injury to a cyst and not squeezing it may reduce inflammation, infection, and scarring. This does not prevent the cyst from existing.

If you have an inherited condition that causes cysts in organs, screening and follow-up may identify changes early, but they cannot prevent the genetic condition. For recurring or condition-specific cysts, prevention options are based on the exact type rather than cysts in general.

The course of a cyst depends on its type and location. A small, uncomplicated skin cyst may stay the same size for years. It may slowly grow, become inflamed for a time, drain, or become less noticeable. A drained cyst can refill because its lining may continue producing material.

Some internal cysts shrink or disappear without treatment. Others remain visible on scans but never affect health. Certain inherited conditions can cause new cysts to develop over time and may require long-term organ monitoring.

If observation is recommended, follow the planned schedule rather than arranging repeated scans on your own. Imaging is usually repeated only when the cyst type, symptoms, or earlier findings make it useful.

You can keep track of a visible cyst by noting changes in size, pain, skin colour, or drainage. Avoid repeatedly pressing it, since this can irritate the area. If a cyst affects comfort, movement, work, sleep, or confidence, those effects are reasonable to discuss during routine care.

Removing one cyst does not always prevent another from forming elsewhere. When the full cyst wall is removed, that particular cyst is less likely to return, but recurrence remains possible.

Arrange a routine medical appointment for:

• A new or unexplained lump
• A lump that persists, grows, becomes firm, or changes shape
• A recurring cyst or one that repeatedly drains
• A breast, testicular, neck, or abdominal lump
• A cyst that interferes with movement or daily activities
• A cyst found on imaging when the follow-up plan is unclear

Seek prompt medical advice if a cyst becomes increasingly painful, red, hot, or swollen, especially if there is pus, fever, or spreading redness. These symptoms may indicate infection. A rapidly enlarging lump or severe new tenderness also needs timely assessment.

Seek emergency care for:

• Sudden, severe abdominal or pelvic pain, especially with vomiting or fainting
• Sudden severe testicular pain or swelling
• New weakness, confusion, seizure, loss of consciousness, or difficulty speaking
• Trouble breathing or swallowing caused by swelling
• Severe pain with fever and rapidly spreading redness
• Heavy bleeding, collapse, or signs of shock

These symptoms can have causes other than a cyst, but they should not wait for a routine appointment.

Is a cyst cancer?

Most cysts are not cancer. A cyst is a sac, while cancer is uncontrolled growth of abnormal cells. However, some tumours can look partly cystic, and a lump cannot always be classified by touch alone. Imaging or tissue testing may be needed when its features are uncertain.

Will a cyst go away on its own?

Some cysts shrink or disappear, while others remain unchanged or slowly grow. This is strongly influenced by the cyst type and location. A persistent cyst does not necessarily need removal if it has a clear benign appearance and causes no problems.

Can I pop or drain a cyst myself?

No. Puncturing or squeezing it can introduce bacteria, push material deeper into the tissue, and cause inflammation or scarring. It may also fail to remove the cyst wall, allowing the cyst to refill.

What is the difference between a cyst and an abscess?

A cyst is an enclosed sac that may or may not be inflamed. An abscess is a collection of pus caused by infection. Abscesses are more likely to be painful, hot, red, and associated with fever, although symptoms can overlap.

What is the difference between a cyst and a tumour?

A cyst usually contains fluid or other material. A tumour is an abnormal growth of tissue and is usually more solid. Both can be benign, and scans sometimes show mixed features. Examination alone may not provide a definite answer.

Does every cyst need surgery?

No. Many cysts only need observation. Surgery may be considered when a cyst causes symptoms, repeatedly returns, presses on important structures, has uncertain features, or creates a significant practical or cosmetic problem.