Seborrheic Keratoses – So Odd, So Common

Seborrheic keratoses (seb-o-REE-ik care-uh-TOE-sees), referred to as “SKs,” are among the most common skin growths. Although benign, they usually look suspicious and concerning, which sends people running to the dermatologist. These growths generally appear in middle-aged and older adults. They have an autosomal dominant mode of inheritance in about half of patients, which means they’re often a family trait, and sunlight seems to be a factor in their development, as well. While some people get a solitary lesion or a limited number of SKs, it’s much more likely that a person has a cluster or collection of them. They can spontaneously arise anywhere on the skin, sparing the palms, soles, and mucous membranes, but predominately appear in areas most exposed to sunlight – the face, chest, shoulders, and back.

SKs are not contagious, and they are usually asymptomatic (without symptoms), meaning they may go unnoticed. However, they can become itchy or mildly tender, particularly in areas of repeated friction like the bra area, groin creases, and upper back.

Most SKs start as small, waxy or velvety bumps. Over time, individual lesions typically thicken and develop a rougher surface. They range in color from off-white to pink to dark brown or even black. Darker skin usually means darker SKs.

Common Signs & Symptoms

  • Range of colors
  • Round or oval-shaped
  • “Stuck-on” look with sharply defined margins
  • Flat or slightly elevated with a scaly surface
  • Range from very small to more than one inch wide
  • Asymptomatic but may itch or hurt

When to Make an Appointment

It’s important to have these lesions assessed by a trained eye because they can mimic warts, moles, actinic keratoses (pre-cancers), and skin cancer. Since their texture is an important clue, dermatologists will feel these lesions during evaluation. Causes for concern include:

  • Many growths develop within a few weeks to a few months. Normally, SKs appear one or two at a time over several years.
  • A lesion becomes irritated with friction from clothing or handbags, particuarly if bleeding occurs. This is a good reason for removal.
  • You notice ANY suspicious changes in your skin, such as new sores or growths that grow rapidly, bleed or hurt, or don’t heal. Any of these signs can indicate skin cancer.

SK Removal

Most dermatologists do not advise removal unless a SK (or group of SKs) becomes painful/irritated or unsightly. An SK or group of SKs that is red, swelling, causing an itchy or burning sensation, or possibly bleeding may be diagnosed as “inflamed” or “irritated,” and this situation usually warrants prompt removal. An inflamed SK may be confused with or difficult to differentiate from a malignant melanoma or a squamous cell carcinoma. A dermatologist will biopsy (cut out some or all of) the lesion for a definitive diagnosis if she has any doubt.


An classic, inflamed SK

Examples of inflamed or very dark SKs that might prompt biopsy due to their irregularity:


There are several methods of removal, including:

  1. Freezing with liquid nitrogen (cryosurgery). LN may not work on large, thick growths, and it may cause temporary or permanent discoloration of the treated or surrounding skin.
  2. Burning, or electrocautery or hyfrecation. Burning an SK with an electric current can be very effective, but it may leave discoloration or even scars, and it usually takes more in-office time than other removal methods.
  3. Scraping, or curettage. Sometimes curettage is used along with the freezing or burning to fully remove any SK left behind.
  4. Laser removal, or ablation. Different types of laser treatments are available. A dermatologist may apply a dark pigment with a marker to help attract and concentrate the laser light, which makes the procedure more effective.

The frustrating reality is that there is no way to prevent new SKs from appearing. No matter the removal technique, elimination of a single or group of SKs may be short-lived, as the potential for new growth of SKs is strong – at the treated site or a distal area. Thus, those who elect to remove clusters of SKs often do so on a rotational schedule with periodic “maintenance” visits, eradicating new batches as they arise.


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