Seborrheic keratoses are raised growths that appear on the skin. They are non-cancerous, completely benign, and one of the most common tumors to occur in older individuals. They are called many different names: wisdom spots, maturity spots, age spots, senile warts, and sometimes, humorously, barnacles. In dermatologist speak they are referred to simply as SKs. The name originates from the term “seborrhea” which means excess sebum or grease and from the term “keratosis” which is a thickening of the skin. 

The most common reason for people to get seborrheic keratoses is genetics. Typically if one or both parents have been affected there is a strong likelihood that a patient will develop these. Unlike true warts, they are not caused by a virus, they are not contagious, and they do not spread. Occasionally, these growths can grow during pregnancy, after other hormonal alterations, and in response to underlying medical problems. They do tend to get very dark when sunless tanner is applied, but this is not associated with any increased risk.



Seborrheic keratoses can appear anywhere on the body. Some individuals may have just one or two, but it is far more common to have multiple seborrheic keatoses. They may appear in clusters on the body in a “Christmas tree” pattern because of the skin cleavage lines. They can range in color from white to black, but typically they start off as light tan and gradually darken to darker brown or nearly black.

The most consistent characteristic of seborrheic keratoses is their waxy, “stuck-on” appearance. They look as if someone pasted them onto the skin, and in truth, they do not extend past the epidermis into the dermis. They may take on a warty appearance with time, and on close examination, they can exhibit tiny white cysts and pore-like opening on the surface.

There are a few common variants of seborrheic keratoses that are typical of certain skin types. Darker-skinned individuals can develop what’s called dermatosis papulosa nigra, which are small dark brown to black seborrheic keratoses clustered on the cheeks and sometimes neck and chest. Lighter-skinned individuals may have small, white stuck-on papules on the lower legs that are referred to as stucco keratoses because of their resemblance to the building material.

Learn about how these benign lesions are treated here.



A seborrheic keratosis can be diagnosed by examination alone. A board-certified dermatologist is trained to recognize a seborrheic keratosis just by looking at it. Occasionally, if it has turned very dark black in color, a skin biopsy may be done to ensure that it is not an atypical nevus or a melanoma. 

These growths do not turn into skin cancer, and despite their irregular appearance, there is no risk of melanoma arising from these lesions. Therefore, treatment is aimed at cosmetics purposes. Since they can be unsightly at times, some patients prefer to have them removed. Also, at times they can become rubbed or traumatized, or they can become inflamed on their own. If this happens, it is a good idea to have them removed.

If seborrheic keratoses are being removed because of inflammation or irritation in just one or two spots, insurance companies will typically cover the cost of the removal. However, if they are being removed for cosmetic purposes, the patient is responsible for the cost of removal.

Because seborrheic keratoses are just on the surface of the skin, removal does not usually result in a great amount of scarring. The most common method of removal and the method that is used when there are multiple lesions to be treated is with liquid nitrogen therapy. This results in the lesions turning red, making a small blister, and then ultimately scabbing off. If there is just one or two irritated or troublesome lesions, these may be removed with curettage, which is scraping off the lesion after local anesthetic is administered. There is minimal downtime, and usually there is minimal scarring.