What Is A Cyst? What Causes Cysts?

A cyst is a closed sac-like structure - an abnormal pocket of fluid, like a blister - that contains either liquid, gaseous, or semi-solid substances. A cyst is located within a tissue, and can occur anywhere in the body and can vary in size - some are so small they can only be viewed through a microscope, while others may become so big that they displace normal organs.

In anatomy, a cyst can also refer to any normal bag or sac in the body, such as the bladder. In this article, cyst refers to an abnormal sac or pocket in the body that contains either liquid, gaseous or semi-solid substances.

A cyst is not a normal part of the tissue where it is located. It has a distinct membrane and division on nearby tissue - the outer or capsular portion of a cyst is called the cyst wall. If the sac is filled with pus it is not a cyst, it is an abscess.

The English word cyst comes from the Latin word cystis, which came from the Ancient Greek word kystis, meaning "bladder" or "pouch".

What causes cysts?

Cysts can be caused by:

• Tumors
• Genetic conditions
• Infections
• A fault in an organ of a developing embryo
• A defect in the cells
• Chronic inflammatory conditions
• Blockages of ducts in the body which cause a fluid build-up
• A parasite
• Impact injury that breaks a vessel

Benign and malignant cysts

Most cysts are benign and are caused by plugged ducts or other natural body outlets for secretions. However, some cysts may be tumors and are formed inside tumors - these can be potentially malignant. Examples include keratocysts and dermoid cysts.

What are the possible signs and symptoms of a cyst?

Signs and symptoms vary enormously, depending on what type of cyst it is. In most cases the patient becomes aware of an abnormal lump - as is usually the case with cysts of the skin or just below the skin.

A cyst in the mammary glands (breasts) may be noticeable when the breasts are examined by touching them - the lump will be palpable. Breast cysts are often painful.

Some cysts in the brain can cause headaches, as well as other symptoms.

Many internal cysts, such as those in the kidneys or the liver may not have any symptoms and go unnoticed until an imaging scan (MRI scan, CAT scan, ultrasound) detects them.

What is the treatment for a cyst?

Treatment for a cyst will depend on various factors, including the type of cyst, where it is, its size, and the degree of discomfort it is causing.

A very large cyst that causes symptoms can be surgically removed. Sometimes the doctors may decide to drain or aspirate the cyst by inserting a needle or catheter into the cavity. If the cyst is not easily accessible, drainage or aspiration is often done with the help of radiologic imaging so that the doctor can accurately guide the needle/catheter into the target area.

Sometimes the aspirated liquid is examined under a microscope to determine whether cancerous cells are present.

If doctors suspect the cyst may be cancerous it may be removed surgically, or a biopsy of the capsule (cyst wall) may be ordered.

Many cysts arise as a result of a chronic or underlying medical condition, as may be the case with fibrocystic breast disease or polycystic ovary syndrome - in such cases the focus of treatment is on the medical condition.

Types of cysts

Below is a list of some of the most common cysts:

• Acne cyst - go to What is cystic acne?


• Arachnoid cyst - the arachnoid membrane covers the brain. During fetal development the arachnoid membrane doubles up or splits to form an abnormal pocket of cerebrospinal fluid. In some cases doctors need to drain the cyst. Arachnoid cysts may affect newborn babies.


• Baker's cyst - also called a popliteal cyst. The patient experiences a bulge and a feeling of tightness behind the knee. Pain gets worse when extending the knee or during physical activity. Usually caused by a problem with the knee joint, such as arthritis or a cartilage tear.


• Bartholin's cyst - may occur if the ducts of the Bartholin glands (situated inside the vagina) become blocked. Patients may undergo surgery and/or be prescribed antibiotics.


• Breast cyst - often painful and usually need to be drained. Some studies have indicated that breast cysts may point to a raised breast cancer risk.


• Chalazion cyst - very small eyelid glands (meibomian glands) make a lubricant that comes out of tiny openings in the edges of the eyelids. Cysts can form if the ducts are blocked.


• Colloid cyst - a cyst containing gelatinous material in the brain. In most cases, the recommended treatment is surgical removal of the cyst.


• Dentigerous cyst - a cyst surrounding the crown of an unerupted tooth.


• Dermoid cyst - a type of cyst that has mature skin, hair follicles, sweat glands, even clumps of long hair sometimes, as well as fat, bone, cartilage, and thyroid tissue.


• Epididymal cyst - a cyst (spermatocele) that forms in the vessels attached to the testes. This type of cyst is estimated to affect 30% of American males and doesn't typically impair fertility or require treatment. If it causes discomfort a doctor may suggest surgery.


• Ganglion cyst - go to What is a ganglion? What is a ganglion cyst?


• Hydatid cyst - a relatively small tapeworm forms cysts in the lungs or liver. Treatment includes surgery and medication.


• Ovarian cyst - the majority of ovarian cysts are benign. Some can become so large that the woman looks pregnant. Ovarian cysts 5cm long or less are common during a woman's reproductive years.


• Pancreatic cysts - most are pseudocysts; they don't have the type of cells found in true cysts. May include cells normally found in other organs, such as the stomach or intestines.


• Periapical cyst - also known as radicular cysts. It is the most common odontogenic (relating to the formation and development of teeth) cyst. Usually caused by inflammation of the pulp, pulp death, or dental caries.


• Pilar cyst - also known as a trichilemmal cyst. It is a fluid-filled cyst that forms from a hair follicle. Most commonly found in the scalp.


• Pilonidal cyst - forms in the skin near the tailbone (lower back), and can sometimes contain ingrown hair. This type of cyst can grow in clusters which sometimes create a hole or cavity in the skin.


• Renal cyst (kidneys) - several types of cysts can develop in the kidneys. Solitary cysts contain fluids and may sometimes also have blood. Some are present at birth. Others may be caused by tubular blockages. Patients with kidney vascular diseases may have cysts formed by the dilatation of blood vessels.


• Pineal gland cyst - a benign cyst that forms in the pineal gland in the brain. According to autopsy records, pineal gland cysts are fairly common.


• Sebaceous cyst - the skin is lubricated by sebaceous fluid which can build up inside a pore or hair follicle and form a lump filled with thick, greasy substances. Most commonly found on the skin of the face, back, scalp and scrotum.


• Tarlov cyst - also known as perineural/perineurial cysts, as well as sacral nerve root cysts. The cysts are located at the base of the spine and are filled with cerebrospinal fluid.


• Vocal fold cyst - there are two types, mucus retention cysts and epidermoid cysts. Vocal fold cysts can interfere with the quality of the patient's speech, sometimes causing vocal cords to produce multiple tones simultaneously (diplophonia), or hoarseness and breathy speech (dysphonia).

Sources: National Health Service (NHS), UK, The Mayo Clinic, Wikipedia, HHS (Department of Health and Human Services USA), NIH (National Institutes of Health, USA).