Epidermoid cysts, also known as epidermal inclusion cysts or keratin cysts, are non-cancerous bumps that develop beneath the skin’s surface. These common skin growths can appear anywhere on the body but are most frequently found on the face, neck, back, and trunk. While epidermoid cysts are typically harmless, understanding their symptoms can help you identify them early and seek appropriate medical attention when necessary.
These cysts form when skin cells move deeper into the skin and multiply instead of shedding normally. The cells form a sac-like structure that fills with a soft, yellowish substance called keratin. Although epidermoid cysts grow slowly and are usually painless, they can become uncomfortable or cosmetically concerning depending on their size and location.
1. Small, Round Bump Under the Skin
The most characteristic symptom of an epidermoid cyst is a small, round, or dome-shaped lump that you can feel beneath the surface of your skin. This bump is typically firm to the touch and moves slightly when pressed.
The cyst under skin usually ranges from a few millimeters to several centimeters in diameter, though most remain relatively small. The overlying skin generally appears normal in color, though it may sometimes look slightly yellow or have a central pore-like opening called a punctum. This opening is a telltale sign that distinguishes epidermoid cysts from other types of skin lumps.
These bumps develop gradually over weeks to months, and many people don’t notice them until they’ve reached a noticeable size. The slow growth pattern is characteristic of benign cysts and helps differentiate them from more concerning skin conditions.
2. Skin-Colored or Yellowish Appearance
Epidermoid cysts typically appear as skin-colored bumps, blending relatively well with the surrounding tissue. However, some cysts may have a slightly yellowish tint due to the keratin content visible through the thin overlying skin.
A distinctive feature you might notice is a small, dark, central point on the cyst’s surface – the aforementioned punctum. This represents a widened pore or follicular opening and is particularly common in cysts on the face or back. The punctum may occasionally release a thick, cheese-like, white or yellow material with a characteristic unpleasant odor.
The appearance of the cyst generally remains consistent unless it becomes infected or inflamed, at which point the color may change to red or purple.
3. Painless Growth (In Most Cases)
Most epidermoid cysts are completely painless and cause no discomfort. Many people live with these cysts for years without experiencing any pain or complications, only seeking medical attention for cosmetic reasons or when the cyst grows to a bothersome size.
The painless nature of these cysts is due to their benign, slow-growing characteristics and the fact that they typically don’t affect surrounding nerves or structures. A cyst on the neck or other visible areas may cause more concern due to appearance rather than physical discomfort.
However, it’s important to note that painlessness is not universal – certain circumstances can change this characteristic symptom, as described in the following sections.
4. Tenderness and Pain When Inflamed or Infected
While epidermoid cysts are usually painless, they can become tender, painful, and uncomfortable if they become inflamed or infected. This is one of the most common complications associated with these cysts.
Inflammation can occur due to trauma to the cyst, attempted squeezing or draining, or rupture of the cyst wall, which releases the irritating keratin material into surrounding tissues. When infected, the area around the cyst becomes red, warm to touch, swollen, and increasingly painful. You may also notice the cyst growing larger more rapidly than before.
An infected cyst may develop into an abscess, containing pus rather than just keratin. This requires prompt medical attention to prevent the infection from spreading to surrounding tissues. Signs of infection include increasing pain, redness spreading beyond the cyst, warmth, fever, and discharge of pus.
5. Thick, Foul-Smelling Discharge
One of the more unpleasant symptoms of epidermoid cysts is the occasional discharge of their contents through the central punctum. This discharge consists primarily of keratin, a protein that builds up inside the cyst, along with dead skin cells.
The material appears as a thick, white, yellowish, or cheese-like substance with a distinctly unpleasant, often described as “cheesy” or rancid odor. This smell is caused by the breakdown of keratin and cellular debris within the sealed environment of the cyst.
Discharge may occur spontaneously, especially as the cyst grows larger and pressure builds up inside. It’s more likely to happen if the cyst is squeezed, pressed, or traumatized. While this discharge may temporarily reduce the size of the cyst, it doesn’t eliminate the cyst wall itself, so the cyst typically refills over time. Attempting to squeeze or drain a cyst at home significantly increases the risk of infection and inflammation.
6. Slow, Gradual Growth Over Time
Epidermoid cysts are characterized by very slow, gradual growth. Most people notice that their cyst remains roughly the same size for months or even years, with only minimal changes.
This slow growth rate is an important distinguishing feature that helps differentiate epidermoid cysts from more serious conditions. A cyst on the back, for instance, might be present for years before becoming large enough to cause concern or discomfort.
The growth rate can occasionally accelerate if the cyst becomes inflamed or if there’s repeated trauma to the area. Some cysts reach a certain size and then stop growing altogether, while others continue to slowly enlarge over many years. Rapid growth, especially when accompanied by other concerning symptoms like bleeding, hardness, or irregular borders, should prompt immediate medical evaluation to rule out other conditions.
7. Mobility Beneath the Skin
A defining characteristic of epidermoid cysts is that they are typically mobile, meaning they can be moved slightly when you press on them. This mobility occurs because the cyst is not firmly attached to deeper tissues beneath the skin.
When you gently push on the cyst, you should be able to feel it shift position slightly under your finger. This is different from other types of growths that may be fixed to underlying structures and don’t move when pressed.
However, if a cyst becomes inflamed or infected, it may temporarily lose some of this mobility due to swelling and inflammation of surrounding tissues. A cyst on the face or other areas with less subcutaneous tissue may also feel less mobile than one located in areas with more fatty tissue, such as the back or neck.
Main Causes of Epidermoid Cysts
Understanding what causes epidermoid cysts can help you better comprehend why these growths develop and potentially identify risk factors. Here are the primary causes:
Blocked Hair Follicles: The most common cause of epidermoid cysts is blockage of hair follicles or damaged hair follicles. When a follicle becomes obstructed, skin cells can become trapped beneath the surface and begin to multiply, forming a cyst.
Skin Trauma or Injury: Damage to the skin from cuts, surgical wounds, acne, or other injuries can cause skin cells to be implanted deeper into the dermis. These displaced cells continue to multiply and produce keratin, eventually forming a cyst. This is why epidermoid cysts are sometimes called epidermal inclusion cysts.
Developmental Factors: Some epidermoid cysts are present from birth or develop due to developmental abnormalities during fetal development. These congenital cysts occur when skin cells become trapped during the formation of various body structures.
Genetic Predisposition: Certain genetic conditions, such as Gardner’s syndrome, increase the likelihood of developing multiple epidermoid cysts. People with a family history of these cysts may also be more prone to developing them.
Acne and Skin Conditions: Individuals with a history of severe acne are at higher risk of developing epidermoid cysts, particularly on the face and back. The inflammation and damage caused by acne can contribute to cyst formation.
Age and Hormonal Factors: Epidermoid cysts are most common in adults, particularly during and after puberty when hormonal changes affect the skin. They are rare in children and elderly individuals.
Prevention Strategies
While it’s not always possible to prevent epidermoid cysts entirely, especially those related to genetic factors or developmental causes, certain strategies may help reduce your risk:
Avoid Skin Trauma: Protect your skin from unnecessary injury. When you do experience cuts or wounds, ensure they are properly cleaned and allowed to heal correctly to minimize the risk of skin cells becoming trapped beneath the surface.
Don’t Squeeze or Pick at Skin: Avoid squeezing pimples, blackheads, or any existing cysts, as this can damage the skin and increase the risk of new cyst formation or infection of existing ones. If you already have an epidermoid cyst, resist the temptation to squeeze or puncture it yourself.
Maintain Good Skin Hygiene: Keep your skin clean and healthy by washing regularly with gentle cleansers. This helps prevent follicle blockage and reduces the risk of infection if you already have cysts.
Manage Acne Properly: If you’re prone to acne, especially on your face, back, or neck, seek appropriate treatment to minimize scarring and skin damage that could contribute to cyst formation. Consult with a dermatologist for proper acne management.
Protect Your Skin from Sun Damage: While sun exposure isn’t a direct cause of epidermoid cysts, maintaining overall skin health through sun protection can support your skin’s normal function and healing processes.
Regular Skin Checks: Monitor your skin for any new growths or changes to existing lumps. Early identification allows for prompt evaluation and management if needed.
Frequently Asked Questions
Are epidermoid cysts dangerous or cancerous?
No, epidermoid cysts are benign (non-cancerous) growths and are not dangerous in most cases. They very rarely become cancerous. However, you should have any new or changing skin lumps evaluated by a healthcare provider to confirm the diagnosis and rule out other conditions.
Can epidermoid cysts go away on their own?
Epidermoid cysts typically don’t disappear on their own. While they may occasionally drain and temporarily shrink, the cyst wall remains and will likely refill. Complete removal usually requires a minor surgical procedure performed by a healthcare professional.
What’s the difference between an epidermoid cyst and a sebaceous cyst?
Although the terms are often used interchangeably, they are technically different. Epidermoid cysts are filled with keratin from skin cells, while true sebaceous cysts (which are much rarer) originate from sebaceous glands and contain oily sebum. Most cysts people refer to as “sebaceous cysts” are actually epidermoid cysts.
Should I squeeze or pop an epidermoid cyst?
No, you should never attempt to squeeze, pop, or drain an epidermoid cyst yourself. This can lead to infection, inflammation, scarring, and may make the cyst more difficult to remove later. If a cyst is bothersome, consult a healthcare provider for proper evaluation and treatment options.
When should I see a doctor about a cyst?
You should see a doctor if your cyst becomes painful, red, swollen, warm, or starts draining pus (signs of infection); if it grows rapidly; if it’s in a cosmetically concerning location; if it interferes with daily activities; or if you’re simply unsure whether the lump is actually a cyst. Any new or changing skin growth should be evaluated by a healthcare professional.
Can epidermoid cysts come back after removal?
If the entire cyst, including the cyst wall, is completely removed during a surgical procedure, recurrence is unlikely. However, if any part of the cyst wall remains, the cyst can grow back in the same location. Proper surgical removal by a qualified healthcare provider minimizes the risk of recurrence.
How long do epidermoid cysts last?
Without treatment, epidermoid cysts can persist indefinitely. Some remain the same size for years, while others slowly grow over time. They do not have a natural life cycle that leads to spontaneous resolution, which is why surgical removal is often recommended for cysts that are symptomatic or cosmetically concerning.
References:
- Mayo Clinic – Epidermoid Cysts
- American Academy of Dermatology – Epidermoid Cysts
- National Center for Biotechnology Information – Epidermoid Cyst
- NHS – Epidermoid Cysts
- Cleveland Clinic – Epidermoid Cysts
The information on this page is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions related to your health.
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