Most epidermoid cysts are small, typically ranging from 0.5 to about 5 cm in diameter; they often grow slowly, but rapid enlargement may suggest inflammation or infection and should be medically assessed.
Epidermoid cysts are common, benign, slow growing lumps beneath the skin that develop when surface skin cells become trapped and continue producing keratin within a thin sac.
Epidermoid cysts are common, slow-growing, benign lumps beneath the skin. They arise when surface skin cells (epidermal cells) become trapped below the outer layer of skin, forming a sac that fills with the protein keratin.
These cysts are often called ‘sebaceous cysts’ in everyday language, but technically this term is misleading because true sebaceous cysts originate from oil glands and are rare. Epidermoid cysts develop from skin cells rather than sebaceous glands. They can occur at any age but are most common in adults, particularly on the face, neck, chest and back.
No. Epidermoid cysts are not contagious.
They are not caused by bacteria, viruses or fungi, and they cannot spread from one person to another through touch or close contact. An epidermoid cyst forms when skin cells become trapped beneath the surface of the skin and continue producing keratin. It is a structural skin issue rather than an infectious condition.
Even if a cyst becomes inflamed or infected, the cyst itself is not contagious. However, if infection develops, appropriate medical treatment may be required.
Epidermoid cysts most often appear on areas with hair follicles, including:
They rarely occur on the palms of the hands or soles of the feet.
Epidermoid cysts are harmless. They usually grow slowly and may remain unchanged for years. However, any new, changing or painful lump should be assessed by a healthcare professional to confirm the diagnosis and exclude other conditions.
Epidermoid cysts often cause no symptoms and may go unnoticed for years. Typical features include:
Most epidermoid cysts are small, typically ranging from 0.5 to about 5 cm in diameter; they often grow slowly, but rapid enlargement may suggest inflammation or infection and should be medically assessed.
If a cyst ruptures, it may release a thick, yellowish, foul smelling, cheese like material made of keratin.
Inflammation or infection may cause:
Medical advice should be sought if a cyst grows quickly, becomes painful, repeatedly becomes inflamed, changes in appearance, or is located in an area that is frequently irritated.
Epidermoid cysts develop when skin cells that would normally shed from the surface become trapped beneath the skin. These cells continue producing keratin within a closed sac, leading to cyst formation.
Possible contributing factors include:
In many cases, there is no clear cause. There is no reliable method to prevent cyst formation.
Diagnosis is usually made through clinical examination by a healthcare professional. The appearance, location and feel of the lump are often sufficient to confirm the diagnosis.
Additional tests are rarely necessary. However, further investigation may be considered if:
In selected cases, imaging (such as ultrasound) or examination of removed tissue under a microscope may be performed.
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.
Most epidermoid cysts do not require treatment if they are painless and not causing problems. Observation and monitoring are often appropriate.
Treatment may be considered if a cyst becomes inflamed, infected, uncomfortable or cosmetically concerning.
Do not squeeze, puncture or attempt to remove a cyst yourself. This can:
Epidermoid cysts are usually benign and slow growing. Many remain stable and cause no long term problems.
Most cysts can be left untreated unless they cause symptoms or concern. When completely removed, surgical treatment is generally curative. Cysts that are only drained rather than fully removed with the capsule are more likely to return. Complete surgical excision minimises recurrence.
Some epidermoid cysts may remain stable in size for years, and occasionally they may shrink slightly. However, most cysts do not disappear completely without treatment.
Because the cyst wall continues producing keratin, the lump often persists unless it is surgically removed. In some cases, a cyst may rupture and drain, which can temporarily reduce its size, but recurrence is common if the capsule remains intact.
Observation is usually safe if the cyst is painless and not changing.
Epidermoid cysts are almost always benign. Malignant transformation is extremely rare.
However, any lump that:
Should be evaluated by a healthcare professional to exclude other conditions. It is important not to assume that all lumps are harmless cysts. Clinical examination ensures accurate diagnosis.
There is no known way to completely prevent epidermoid cysts. They often develop without a clear trigger. Avoiding unnecessary skin trauma and managing skin irritation may help reduce the risk of inflammation or secondary infection.
Medical assessment is recommended if a cyst:
You should also seek medical advice if you are unsure whether a lump is a cyst. Many different skin conditions can appear similar, and accurate diagnosis is important.
If your epidermoid cyst grows, becomes painful or repeatedly inflamed, seek professional advice. We offer a free online skin and cyst assessment to provide personalised guidance and discuss suitable treatment options.