Atheromas are fairly common benign cysts in the skin. They are also known as epidermal cysts, reflecting the fact that the cyst itself is made up of cells from the top layer of the skin (epidermis). Atheromas typically occur in middle-aged individuals and are seen twice as often in men as in women. They have no specific cause, but certain forms (including atheromas in the scalp) have a degree of hereditary predisposition. There are also rare genetic disorders that can lead to a larger number of atheromas.
Atheromas appear and feel like small to medium-sized skin lumps. They usually lie fairly deep in the skin. Occasionally, a central "pore" can be seen, representing a blocked duct. In terms of size, they can vary from a few millimeters to several centimeters (as large as an egg). Atheromas can occur anywhere on the body, including the face, back, scalp, and genitals. They are most commonly found in areas with hair growth.
Typically, atheromas are soft, painless, and freely movable. The contents, consisting of keratin (skin proteins) and fatty substances, may feel somewhat lumpy. This content usually remains within the capsule but can drain spontaneously onto the skin surface, appearing as a cheesy mass with an unpleasant odor.
Atheromas can also become inflamed and/or infected (bacterial infection). In such cases, they become red, swollen, and tender. The contents of the atheroma are mixed with pus. The diagnosis is primarily based on its appearance. Additional diagnostic tests such as biopsy (tissue sample), ultrasound, or swab for bacterial culture are generally unnecessary. However, further evaluation may be indicated in cases of diagnostic uncertainty.
Atheromas occur when parts of the outer layer of skin (epidermis), often associated with a hair follicle, become trapped beneath the skin. This can happen by chance or due to damage to the skin surface. Overtime, a capsule is formed that pushes away and produces the atheroma masses. Consequently, a continually growing cyst develops in or just beneath the skin.
Atheromas are not dangerous and do not require treatment. They typically grow slowly over many years and change very little over time. Occasionally, they may resolve on their own. It is not possible to squeeze an atheroma to empty it and make it disappear. In that case, the capsule itself would remain, and the sebaceous material could accumulate again.
Atheromas must be completely removed through a minorsurgery under local anesthesia. This is done for cosmetic reasons, discomfort or pain, location concerns, or recurrent infections. The tissue that is removed is always sent for microscopic examination (histopathology) to confirm the diagnosis and rule out other causes. In cases of severely inflamed or infected atheromas, it may be necessary to make an incision in the atheroma to drain its contents. This can prevent the spread of infection, formation of abscesses, and promote healing.
Lipomas (fatty lumps) resemble atheromas. They consist of fatty tissue and have a similar nodular texture.
