What is seborrheic keratoses?

Seborrheic keratoses are skin growths that typically first appear when you reach middle age. They often show up on your temples or torso. People with darker skin can experience multiple seborrheic keratosis growths on their cheekbones called dermatosis papulosa nigra

The size of seborrheic keratoses can vary, and they tend to grow slowly. They are often round or oval-shaped and can be brown, black, or flesh-colored. Their texture can vary from person to person and be waxy, crusty, scaly, or velvety. 

Seborrheic keratoses are caused by a build-up of skin cells in your epidermis (the top layer of your skin), including cells called keratinocytes. Older cells typically get replaced by newer cells when they flake off. Sometimes the keratinocytes in this layer grow faster than normal, resulting in a keratosis

Seborrheic keratoses are usually benign, but they can look similar to cancerous growths.

Signs of seborrheic keratoses

Seborrheic keratoses may:

  • Have a raised surface
  • Appear to be pasted on 
  • Look similar to a wart or a scaly skin growth
  • Stand out from surrounding skin

Seborrheic keratoses can range in color from white to black, but most are tan or brown. Some people develop a cluster of growths in one area.

The condition can be mistaken for other skin issues like moles, skin tags, or warts. Seborrheic keratoses can also itch or become irritated when clothing rubs against them.

Causes of seborrheic keratoses

There is no known cause of seborrheic keratoses. However, some research has found common factors among those who experience them. The growths appear to run in families. Exposure to the sun also seems to play a role in developing seborrheic keratoses.

While seborrheic keratoses are most common in older people, they can appear as early as adolescence. Women who are pregnant or have taken estrogen may also develop them. Seborrheic keratoses rarely occur in children. 

If you develop large seborrheic keratoses or they grow rapidly, you could have cutaneous paraneoplastic syndrome. This condition appears in patients diagnosed with cancerous tumors elsewhere in the body. 

The disorder is often found in people with the following kinds of cancer:

When to see the doctor for seborrheic keratoses

You may want to see your doctor if you notice any of the following:

  • New skin growths
  • Moles that appear to be getting wider
  • Growths that appear uneven
  • Moles with blurry borders
  • Itchiness in an older mole
  • A diagnosed seborrheic keratosis that starts looking differently

It can help to write down any questions you have about your skin growths. Make sure to bring your medical history, and inform your doctor of any medications you are taking that could affect the appearance of your seborrheic keratoses. 

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Diagnosis for seborrheic keratoses

To diagnose your seborrheic keratoses, your doctor will look at them. If your doctor suspects that your growths may be cancerous, they may order a skin biopsy to confirm a diagnosis.

Treatments for seborrheic keratoses

You should not attempt to remove a seborrheic keratosis on your own. You could misdiagnose it, which could allow a more serious medical condition to go undiagnosed. You could also cause an infection.

Most seborrheic keratoses do not require treatment. If a growth becomes uncomfortable, your doctor may recommend one of the following:

  • Liquid nitrogen — Your doctor may use this compound to freeze seborrheic keratoses, causing them to fall off  
  • Surgery — Your doctor may use a numbing cream and a scalpel to cut off the growth or burn the growth off with electricity

Growths removed using one of these methods usually do not grow back. If they do return, your doctor may want to biopsy your skin to make sure the lesions are not cancerous. 

Your skin may appear lighter in the area where a seborrheic keratosis was removed. This can fade with time or may be permanent

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Medically Reviewed on 3/11/2021
References
American Academy of Dermatology Association: "Seborrheic Keratoses: Diagnosis and Treatment."

American Academy of Dermatology Association: "Seborrheic Keratoses: Overview."

American Academy of Dermatology Association: "Seborrheic Keratoses: Who Gets and Causes."

Cedars-Sinai: "Seborrheic Keratosis."

Kaiser Permanente: "Seborrheic Keratoses."

Merck Manual: "Paraneoplastic Syndromes."

Merck Manual: "Seborrheic Keratoses."