Seborrheic keratosis

Seborrheic keratosis are benign (noncancerous) skin growths that develop from skin cells called keratinocytes. These growths have a waxy or greasy look and can be tan, brown or black. One distinguishing characteristic is that they look like they have been glued or stuck onto the skin. Over time, the growths become rough and crusty looking. Seborrheic keratosis are raised growths on the skin. Seborrheic means greasy and keratosis means thickening of the skin. There may be just one or clusters of dozens. They are usually start off light tan, and then may darken to dark brown or nearly black. They may be oval spots a fraction of an inch across, or form long Christmas tree like patterns on the torso inches long.

The consistent feature of seborrheic keratosis is their waxy, pasted-on or stuck-on look. The look is often compared to brown candle wax that was dropped onto the skin. They may be unsightly, especially if they begin to appear on the face.

Seborrheic keratoses do not cause pain or itching. They typically appear as light brown areas on the skin that appear to be "stuck on." Typically, the growth has a defined border that is raised compared to the surrounding skin. The surface can have an irregular appearance. Sometimes there are small white or black circles within the growth itself. These are known as "horn cysts." Some lesions can grow to a very large size and can appear very dark.

Treatment is usually not required unless the growths become irritated or are cosmetically displeasing. Removal is simple and doesn't normally cause scarring, although growths on the torso might leave lighter-colored skin. Keratoses can be removed surgically, frozen off with liquid nitrogen or burned or lasered off. Keratoses usually don't recur after they have been removed, but people who are prone to this condition might develop more.

A small seborrheic keratosis can be frozen with liquid nitrogen. Liquid nitrogen works by freezing and destroying the cells but leaving the connective tissue foundation intact. The lesion frozen forms a blister as the water is released from the now-dead cells then crusts over as that water dries. When the crust falls off after several days, the skin underneath has begun to repair itself. Liquid nitrogen can leave a scar as the repaired skin may have more or less pigment producing cells. The scar is usually flat though unless you have a tendency to form keloids.

Another way seborrheic keratoses can be removed is to shave them off. Because their attachment to the underlying skin covers less area than the lesion itself, shaving can be a viable option. Seborrheic Keratoses are shaved off with a flexible razor blade going just deep enough to get only the seborrheic keratosis cells and leave normal skin. Shaving too much normal skin off can leave a divot in the skin as a scar. After the lesion is shaved, a chemical agent such as aluminum chloride or silver nitrate is applied to the wound to stop any small surface bleeding. Silver nitrate is a dark brown color and the resulting wound after the shave is dark brown. This color will usually go away after the skin repairs but some of that pigment can remain. For this reason, silver nitrate is usually not used on the face.