15. Sebaceous Cysts in the Breast and Axilla
Sebaceous cysts, also referred to as epidermal inclusion cysts, are typically harmless, slow growing bumps felt under the skin. These can occur in many locations of the body, including the breasts and axillae (aka armpit area).
You may notice any of the following with a sebaceous cyst:
- Round bump under the skin
- Dark dot in the center of the bump
- Can grow slowly
- Skin discoloration (usually darker than your natural skin tone)
- Tender or warm to touch
- Thick, smelly, cheesy substance that leaks from the cyst
- Inflamed or infected bump (aka boil)
These typically form randomly when a hair follicle sebaceous gland duct gets blocked. The sebaceous gland produces an oily substance called sebum. If the duct is blocked, sebum continues to be produced but has nowhere to go, and the sebaceous cyst is formed.
Sebaceous cysts can occur at any age, but most frequently occur between 20-60 years of age. They are not contagious.
Sebaceous cysts can become inflamed or infected. This may result in the lump being swollen, painful, and discolored. Sebaceous cysts can also break open with a yellow (often stinky) fluid draining from the cyst.
All new lumps in the breast and armpit should be evaluated by your primary care provider. Your provider may monitor sebaceous cysts during regular breast exams and/or send you for breast imaging. Please follow up with your PCP if the cyst grows rapidly, breaks open, or is painful/looks infected.
A sebaceous cyst may get smaller/resolve on its own, but many will return. Most sebaceous cysts don’t cause problems or need treatment. It is important to NOT try to pop or drain the cyst yourself, as this can cause an infection, and it will likely grow back. If it bursts under the skin, the bacteria could infect the surrounding tissue and spread infection.
If imaging confirms that the lump is a sebaceous cyst, AND your PCP has evaluated the lump and is not concerned about infection, the following may be done at home to try and relieve the sebaceous cyst:
- Gently clean the affected skin with soap
- Apply a wet, warm washcloth for 20-30 min. When it cools, warm it up by dipping it in hot water. Be careful not to burn your skin. The warm compress shouldn’t be any hotter than bath water.
- Repeat 3-4 x a day until the lump comes to a head and starts to drain
- When pus starts coming out of the cyst, apply a clean bandage over the lump to prevent any infection from spreading. DO NOT squeeze to speed up drainage.
- Change the bandage daily until drainage stops.
If there is any concern that the sebaceous cyst is infected, please have your PCP evaluate the cyst. Antibiotics can be used to treat an infected cyst. Your PCP may also refer you to a breast surgeon or dermatologist for further evaluation and to discuss additional treatment options including possible surgical excision.
Written by Danielle Carroll, M.D.
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