What are Seborrheic Keratoses?

Seborrheic keratoses are formed when normal cells build up on top of each other, creating rough bumps that appears to be pasted onto the skin. They are often flesh-colored or have a darker pigment. They typically occur on the back and chest, but are also found on the scalp, face, arms, and legs as well. You may have heard flat seborrheic keratoses be referred to as “liver” or “sun spots.” These spots are so common, many people will have at least one area of them by the time they are 40 or 50. Although we do not know exactly why seborrheic keratoses form, they are most often found in environments where sun exposure is high.

Although seborrheic keratoses are normally found on healthy, mature skin, our patients tend to view their cosmetic appearance as undesirable. 

Due to how common seborrheic keratoses are, many do not seek treatment for these spots from their dermatologist unless they feel it has an odd appearance or experience itching.  Occasionally, we find that very dark colored seborrheic keratoses can mimic melanoma skin cancer to the naked eye, so we recommend getting these and any other suspicious spots examined. 

 

Treatment

Removal is not necessary, but if a patient chooses to have seborrheic keratoses removed several options are available:

  • Cryotherapy: Seborrheic keratoses may be frozen lightly with liquid nitrogen which creates a blister at the site of the lesion that then peels off in about a week. This method causes minimal discomfort, but carries a slight risk of scarring. The risk of scarring is greater in darker skinned patients.
  • Curettage: In this technique, the seborrheic keratosis will be treated with local anesthesia (usually an injection of lidocaine), followed by scraping with a surgical tool called a curette. Once the keratosis is removed in this manner, a base of clean skin is left behind which lowers the risk of scarring. 
  • Shave excision: In shave excision, the seborrheic keratosis is treated with an injection of lidocaine for anesthesia, and a flat blade is used to shave the spot off flat with the surrounding skin, leaving behind a small round lesion. The seborrheic keratosis may then be sent to a pathologist to ensure that it is in fact benign.
  • Less invasive option: A 40% uric acid cream or lactic acid lotion may be applied to help soften or thin out keratoses, and a mild steroid cream or menthol-containing lotion may also be applied to relieve itching.