Some people develop small, wart-like growths, a type of benign tumor called seborrheic keratoses. Though usually harmless, these lesions sometimes resemble more dangerous skin growths. Seborrheic keratosis is extremely common, though many people fail to notice the growths because they are asymptomatic.


A seborrheic keratosis is a benign, waxy, or wart-like tumor. While these growths can be irritating and cause self-consciousness, they are benign or non-cancerous and mostly harmless. For some people, clothing may irritate the lesions, leading to itching and bleeding. Dermatologists have reported swelling and inflammation near the growths in some cases. A single growth may develop, but it is more common to have multiple seborrheic keratoses.

seborrheic keratosis growths kwanchaichaiudom / Getty Images



Each growth has a round shape and ranges in size from a millimeter or less to over an inch in diameter. Seborrheic keratoses often resemble warts or moles. Their colors vary, with brown, yellow, and grey being most common. Growths usually begin as small, rough areas, before eventually developing harder, thicker surfaces. Many people describe seborrheic keratoses as having a “stuck-on” or “pasted” appearance because the tumors only involve the topmost layers of skin.

seborrheic keratosis growth zoom Lipowski / Getty Images



Most commonly, seborrheic keratoses form on the chest, stomach, back, neck, scalp, and face, though they can appear on almost any external body part except the palms or soles of the feet. The lesions also cannot grow on mucous membranes, such as those in the mouth, nose, or genital openings.

dermatologist back skin examination thodonal / Getty Images



Each seborrheic keratosis is the result of benign expansion of epidermal keratinocytes, the most common cells on the outer layer of the skin. While experts believe that there is an inheritable genetic component, no one knows the exact cause. Many researchers think mutations of certain receptors drive the development of the lesions.

genetic researcher lab nicolas_ / Getty Images


Risk Factors

Despite medical uncertainty around seborrheic keratoses, experts have linked the tumors to certain risk factors. People are generally more likely to develop the growths as they age, with those over age 50 having the highest chance. Additionally, people with a family history of the lesions are more likely to develop them. People with lighter skin are also at greater risk.

older adult dermatologist patient ChesiireCat / Getty Images



Diagnosing a seborrheic keratosis is often a simple matter. A dermatologist will observe the growths, noting their “stuck on” appearance and other unique characteristics. Because they often resemble warts and condylomas, a biopsy may be necessary to identify them. Due to variation in appearance and location, some experts classify seborrheic keratoses as different subtypes for more accurate diagnoses.

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The subtypes of seborrheic keratoses are:

  • Acanthotic
  • Hyperkeratotic
  • Clonal
  • Reticulated
  • Irritated
  • Pigmented

biopsy identification seborrheic keratosis Hailshadow / Getty Images


Other Diseases

Several diseases can occur alongside seborrheic keratoses, which means the growths sometimes serve as early warning signs.Basal cell carcinoma most commonly accompanies the growths, though rarely in the same location. Large numbers of seborrheic keratoses can make it difficult to diagnose other conditions. Dermatologists have found more dangerous tumors growing adjacent to or within a seborrheic keratosis.

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Most people with seborrheic keratoses do not need to seek treatment. However, if the growths rapidly multiply or expand, or if they are aesthetically or physically irritating, an individual may request removal. The most common options for treatment are:

  • Cryosurgery: Using liquid nitrogen to freeze and remove the growths
  • Curettage: Manual removal with a scalpel blade or scraping
  • Electrocautery: Destroying the lesion with a high-frequency current, which may leave scars
  • Ablation: Various laser treatments
  • Hydrogen peroxide: 40% solutions of hydrogen peroxide can manage raised growths, but should be used by professionals, only.

dermatologist curettage removal redhumv / Getty Images



Nearly all seborrheic keratoses are harmless, though many people find them unpleasant. Unless the growths are particularly large or in a difficult area, they have no impact on daily life. Treatments can leave small scars or decrease pigmentation in the treated area. In most cases, the removed growths do not return, though others may develop. A small amount of bleeding is common.


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