An epidermoid cyst is a benign growth that develops under the skin, usually on the face, neck, chest, or back. It is also known as a sebaceous cyst, keratin cyst, or epidermal inclusion cyst.
In epidermoid cysts, keratin accumulates on the outer skin, hair, and nails, causing a sac-like structure that forms over time. Keratin can get trapped in hair follicles or small openings in the skin, causing the cyst to grow. Sebum, an oily substance that lubricates the hair and skin, may also be present in the cyst.
Some factors that may increase the risk of developing epidermoid cysts are:
Trauma or injury to the skin
Acne or other skin infections
Hormonal changes
Genetic conditions, such as Gardner syndrome or Gorlin syndrome
Epidermoid cysts are usually painless and slow-growing. They may vary in size from a few millimeters to several centimeters. They typically have the following characteristics:
A round, dome-shaped bump that can be moved under the skin
A smooth, yellowish or whitish surface
A central opening or punctum that may ooze a foul-smelling, cheese-like material
Inflammation, redness, or tenderness if the cyst becomes infected or ruptured
In addition to examining a cyst with a magnifying glass or a dermatoscope, a device that allows a closer look at the skin, a doctor may also use a dermatoscope to diagnose an epidermoid cyst. To rule out other skin conditions, such as skin cancer or cystic acne, a biopsy may also be performed.
Epidermoid cysts do not usually require treatment unless they cause discomfort, cosmetic concerns, or infection. Some of the treatment options are:
Antibiotics, if the cyst is infected
Steroid injections, to reduce inflammation and swelling
Drainage, to remove the contents of the cyst
Surgical excision, to remove the entire cyst and prevent recurrence
Epidermoid cysts cannot be completely prevented, but some measures that may help reduce the chances of developing them are:
Keeping the skin clean and moisturized
Avoiding excessive sun exposure and using sunscreen
Avoiding squeezing, picking, or scratching the cysts
Seeking medical attention if the cysts become inflamed or infected
A cyst on the epidermis is a common and harmless skin growth that can be treated easily if necessary. If the cyst changes in size, shape, color, or texture, or if it bleeds or causes pain, it should be evaluated by a doctor.
