It’s easy to panic when you notice a lump on your skin. You may wonder if it’s melanoma or another type of skin cancer.

But sebaceous cysts — slow-growing bumps under the skin that can appear on the ears, scalp, face, torso, back, or groin area — are typically harmless. And while they can be irritating (or unsightly), they are not cancerous. Here’s what you need to know — and do — if you have a sebaceous cyst.

The first thing to know is that the term “sebaceous cyst” is often used to describe what is actually an epidermoid cyst. The terms are used interchangeably, but there’s a difference, notes the Cleveland Clinic.
True sebaceous cysts are caused by the glands that secrete the oily matter (sebum) that helps lubricate your skin and the hair, per the Mayo Clinic.They are not as common as epidermoid cysts, which occur when skin cells accrue under the skin instead of being shed from its surface. This article will mainly focus on epidermoid cysts.

Signs and Symptoms of an Epidermoid Cyst

These dome-shaped cysts can be pea-sized, or grow to a few inches or larger. They grow very slowly, and they’re not painful. If you touch them, you should be able to move them around. They often have a central small black dot, or punctum, through which sebum accumulates.

Sometimes, however, they can become inflamed, infected, or suddenly rupture, which can increase the risk of infection (more on that later). Occasionally, they occur on a site that is constantly irritated, such as a cyst on your neck that rubs against your collar, or one on your back under a bra strap.

Whatever the cause, if you notice redness, tenderness or warmth, that can indicate that the cyst has become infected. You may also notice that the cyst excretes a cheese-like liquid that has a foul smell.
Unpleasant as that may seem, cysts can disappear on their own without treatment, according to Harvard Health.But if a cyst is bothering you, or becomes painful, it makes sense to see your doctor.

Causes and Risk Factors of an Epidermoid Cyst

The surface of your skin, known as the epidermis, consists of thin layers of cells that are constantly shedding. Sometimes, though, when the cells move deeper into the skin, instead of shedding, they can multiply, leading to cyst formation.

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Acne can contribute to their development, as can damaged or swollen hair follicles.

Sometimes, injury to the skin may cause a sebaceous cyst.

And as for that secretion that can emerge from the cyst? It comes from the cells that form the walls of the cysts. Those cells secrete a protein, known as keratin. These cysts are also made of fat, and it’s often that substance, or infection, that makes the smell, according to American Family Physician.

Duration of Epidermoid Cysts

Cysts can remain small for years or they can keep growing larger. Sometimes, as noted above, a sebaceous cyst can disappear on its own, but surgery is usually necessary to remove them.

Complications of Epidermoid Cysts

Epidermoid cysts can become infected, as already noted. The telltale signs of infection are redness, inflammation, and skin that feels warm to the touch.

If the cyst ruptures, it can also lead to infection, so it’s important to get treatment right away.

In most cases, however, cysts don’t cause problems, and it’s rare for complications or side effects to occur after treatment or surgery.

RELATED: What Is a Skin Lump?

Black and Hispanic Populations and Cysts

Sebaceous cysts are among the most common dermatologic diagnoses in white, Black, and Hispanic individuals, according to a review, published in the Journal of Drugs in Dermatology, of 16 years of data collected from patient visits to U.S. physicians.

Resources We Love

The Cleveland Clinic offers has a quick and clear guide to how these cysts develop and how they’re treated.

While these cysts aren’t skin cancer, if you want to know more about what is and isn’t skin cancer, the National Cancer Institute has a wealth of information, including a tool that can help you recognize the signs. But remember: A doctor is the only one who can tell you for sure.

Additional reporting by Paula Derrow and Kathleen Doheny.

Editorial Sources and Fact-Checking

References

  • Sebaceous Cysts. Cleveland Clinic.
  • Zito P, Scharf R. Epidermoid Cyst. StatPearls. September 2020.
  • Weir C, St. Hilaire N. Epidermoid Inclusion Cyst. StatPearls. August 2020.
  • Epidermoid Cysts. Mayo Clinic.
  • Epidermoid Cysts. Harvard Health Publishing. July 2019.
  • Zuber T. Minimal Excision Technique for Epidermoid (Sebaceous) Cysts. American Family Physician. April 2002.
  • Kim KT, Sun H, Chung EH. Comparison of Complete Surgical Excision and Minimally Invasive Excision Using CO2 Laser for Removal of Epidermal Cysts on the Face. Archives of Craniofacial Surgery. April 2019.
  • Davis S, Narahari S, Feldman S, et al. Top Dermatologic Conditions in Patients of Color: An Analysis of Nationally Representative Data. Journal of Drugs in Dermatology. April 2012.
  • Kawase M, Egawa K, Ishiji T, Nakagawa H. Human Papillomavirus Type 6/11 Identified in an Epidermoid Cyst of the Scrotum. The Journal of Dermatology. February 2018.

Sources

  • Aaron D. Cutaneous Cysts. Merck Manual Consumer Version. September 2020.
  • Agnetta V. Boards Fodder: Cysts. Directions in Residency. Winter 2018.
  • Epidermoid and Pilar Cysts. British Association of Dermatologists. March 2020.

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