Sebaceous Cysts and When to Worry

They usually disappear without treatment but can get infected

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Sebaceous cysts are common skin cysts that can pop up really anywhere on the body but are more frequently seen on the head, back of the ears, neck, and trunk. 

They are believed to result from a clogged hair follicle or skin trauma. In addition, some genetic disorders like Gardner's syndrome may predispose a person to develop sebaceous cysts. 

Some confusion arises around "sebaceous cysts" as these cysts contain keratin, and not sebum (oil) because they originate from the outer layer of the skin (the epidermis) and not the sebaceous glands.

In fact, the true name for sebaceous cyst is an epidermoid cyst, although many people, even health care professionals, still erroneously use the term sebaceous cyst. 

For the purpose of this article and given that the term sebaceous cyst is still often used in the medical community, we will refer to the cyst as such in this article.

What Does a Sebaceous Cyst Look Like?

Sebaceous cysts are painless, soft lumps or bumps that grow slowly just under your skin. They usually have a visible hole in the middle (called a central punctum) and can move freely when touched.

You can see the keratin if the cyst becomes inflamed and breaks open. Keratin is a "pasty" or "cheesy" looking substance that may have a foul odor.

Some sebaceous cysts remain stable in size with time whereas others grow larger which may be uncomfortable and painful, especially if the cyst becomes inflamed.

It's important not to touch or try to remove the substance inside a sebaceous cyst to prevent infection, although this can occur simply on its own.

Signs and symptoms that may indicate an infection of a sebaceous cyst include:

  • Redness
  • Tenderness
  • Increased temperature of the skin over the cyst (it feels warm)

Diagnosis of Sebaceous Cysts

Sebaceous cysts, to the trained eye, are usually easily diagnosed by their appearance. In some cases, a biopsy or skin culture may be necessary to rule out other conditions with a similar appearance.

For instance, an abscess (a collection of pus underneath the skin) or a lipoma (a non-cancerous mass of fatty tissue) can resemble a sebaceous cyst.

To ensure a correct diagnosis, you should see your doctor to receive a formal evaluation.

Treatment of Sebaceous Cysts 

Sebaceous cysts most often disappear on their own and are not dangerous. As stated, however, they may become inflamed, tender, and even infected. 

Sometimes sebaceous cysts grow large enough that they may interfere with your everyday life. When this happens, surgical removal may be necessary, and this procedure can be done at your doctor's office.

Inflamed cysts can often be treated by your doctor who will inject a steroid into the cyst to calm and shrink it. But if your doctor suspects the cyst is infected, it needs to be incised and drained to remove the infected material. Due to the fact that an infected cyst can be painful, your doctor will likely inject an anesthetic (for example, 1 percent lidocaine) around the cyst to numb the area first before draining it.

If an infected sebaceous cyst is not promptly treated, the infection can spread into the surrounding skin. This is called cellulitis, which is a more serious condition, often requiring an oral antibiotic in addition to incision and drainage.

For complete surgical removal of the cyst, including the cyst wall, a doctor will usually wait until the cyst is not inflamed or infected before excising it, as recurrence of the cyst is then much less common.

Besides excision (cutting out the cyst surgically), a study published in the Archives of Plastic Surgery reports on a CO2 laser treatment to remove sebaceous cysts with minimal scarring and low recurrence rates. This may be a good option for people with a cyst on their face or other visible areas.

A Word From Verywell

The big picture here is that it's important to consult your healthcare provider any time you notice any type of growth, bump, or lump on your body.

Although sebaceous cysts are benign, your doctor should examine you to ensure that another more worrisome concern is not present.

Sources:

Goldstein BG, Goldstein AO. (2017). Overview of benign lesions of the skin. In: UpToDate, Dellavalle RP (Ed), UpToDate, Waltham, MA. 

Higgins JC, Maher MH, Douglas MS. Diagnosing common benign skin tumors. Am Fam Physician. 2015 Oct 1;92(7):601-07.

Song SW, Burm JS, Yang WY, Kang SY. Minimally invasive excision of epidermal cysts through a small hole made by a CO2 laser. Arch Plast Surg. 2014 Jan;41(1):85-88.

University of Maryland Medical Center. (April 2015). Sebaceous Cyst.

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