A cyst is a closed sac that can develop within the skin or deeper tissues of the body. It is usually filled with fluid, semi-solid material or keratin. Most cysts are benign (non-cancerous), grow slowly and cause little or no discomfort.
A cyst is a rounded lump formed by a thin wall of tissue that encloses fluid or other material. Skin cysts usually develop just beneath the surface of the skin and may feel smooth, firm or slightly rubbery. They vary in size and may remain unchanged for years or gradually increase in size.
Many do not require treatment, but medical assessment is recommended if a cyst changes, becomes painful, infected or causes concern.
Cysts are very common and can affect people of any age. Skin cysts, including epidermoid and pilar cysts, are frequently seen in adults and are one of the most common reasons for assessment of benign lumps in primary care and dermatology clinics.
Yes. The vast majority of cysts are harmless and do not become cancerous. However, other conditions can appear similar to cysts, so any new, persistent or changing lump should be assessed by a healthcare professional.
Skin cysts most often develop on areas with hair follicles and oil glands, including:
Cysts can also form in other parts of the body, such as the ovaries or kidneys. This page focuses on skin and soft-tissue cysts.
Skin cysts are closed sacs beneath the surface of the skin. They usually grow slowly and are often harmless. Although many cysts look similar from the outside, they form in different ways depending on the tissue they arise from.
Epidermoid cysts are the most common type of skin cyst. They form when surface skin cells move deeper into the skin and continue producing keratin, a protein found in skin and hair. These cysts usually grow slowly and are most often found on the face, neck, chest or back. Many have a small central opening, called a punctum, and may release a thick, yellowish material if they rupture. They are benign but can become inflamed or infected.
Pilar cysts develop from the outer root sheath of a hair follicle and are most commonly found on the scalp. They tend to be firm, smooth and freely movable beneath the skin. Unlike epidermoid cysts, they usually do not have a visible central punctum. Pilar cysts may run in families and are more common in middle-aged adults, particularly women.
The term “sebaceous cyst” is commonly used but medically imprecise. True sebaceous cysts arise from sebaceous (oil) glands and are uncommon. Many cysts described as sebaceous are actually epidermoid or pilar cysts. When present, they may contain an oily or keratin-based material and appear as slow-growing lumps beneath the skin.
Milia are very small cysts that form when keratin becomes trapped just beneath the skin surface. They appear as tiny white or yellowish bumps, most commonly on the face, especially around the eyes and cheeks. Milia are harmless and often resolve on their own, although they can be removed for cosmetic reasons.
Not all cysts occur in the skin. Some develop in deeper tissues or near joints.
Dermoid cysts are congenital cysts that form before birth when skin cells and related structures become trapped during early development. When they occur in the skin, they often present as slow-growing, painless lumps near the face, scalp or neck.
Dermoid cysts may contain keratin, hair follicles and sebaceous material. They can also develop internally, most commonly in the ovaries, where they are known as ovarian dermoid cysts. These are usually benign but may require monitoring or surgical removal.
Ganglion cysts
Ganglion cysts are fluid-filled swellings that develop near joints or tendons, most commonly on the wrist or hand. Their size may change with activity. They are not skin cysts but can appear as visible lumps beneath the skin.
Pilonidal cysts
Pilonidal cysts form near the cleft of the buttocks and often contain hair and skin debris. They can become inflamed or infected and may recur if not fully treated.
Breast cysts
Breast cysts are fluid-filled sacs within breast tissue. They are usually benign and may fluctuate in size due to hormonal changes.
Ovarian cysts
Ovarian cysts develop on or within the ovaries. Many are related to the menstrual cycle and resolve without treatment, although some require monitoring or intervention depending on their size and symptoms.
A typical skin cyst may:
Some cysts, particularly epidermoid cysts, have a small central opening (punctum).
A cyst may become symptomatic if it:
Symptoms may include redness, swelling, warmth, tenderness or discharge of thick, foul-smelling material.
Cysts can develop due to:
Cysts are not caused by poor hygiene and are not contagious.
Most cysts are diagnosed during a physical examination. A GP or dermatologist will assess the lump’s size, texture, mobility and appearance to determine whether it is consistent with a cyst.
Further tests are not usually required. However, imaging such as ultrasound may be recommended if:
A biopsy or surgical removal may be advised if there is concern about another diagnosis.
True skin cysts are almost always benign. Very rarely, skin cancers or other growths can resemble cysts, which is why professional assessment is important for new or changing lumps.
No. Many cysts can be safely left alone if they are small, painless and not causing problems. Observation and monitoring are often appropriate.
Treatment may be considered if a cyst:
Treatment depends on symptoms and cyst type and may include:
Squeezing or attempting to pop a cyst at home is not recommended, as this increases the risk of infection, scarring and recurrence.
Yes. If the cyst lining is not completely removed, the cyst may reform. Complete surgical removal significantly reduces the chance of recurrence.
The outlook for most cysts is excellent. Many remain stable and cause no long-term issues. When treatment is required, outcomes are usually very good, particularly after complete removal.
Most cysts do not cause complications. When problems do occur, they are usually mild and may include:
Although serious complications are rare, any cyst that becomes painful, inflamed, rapidly enlarging or changes in appearance should be assessed by a healthcare professional.
There is no reliable way to prevent cysts from forming, as they often result from normal processes within the skin.
Avoid picking, squeezing or irritating lumps. Seek early medical advice for new or changing lumps. Manage skin conditions, such as acne, that can contribute to blocked follicles
You should see a GP or dermatologist if a lump:
Early assessment helps confirm the diagnosis and ensures appropriate care.
If a cyst grows, becomes painful, or recurs frequently, professional evaluation is essential. Aventus Clinic offers a free online skin and cyst assessment to provide safe, personalised guidance for effective treatment.
