Keratosis, seborrheic: A benign skin disorder due to excessive growth of the top layer of skin cells, usually found in persons over 30 years old. They may appear as just one growth or in clusters. They are most often brown but can differ in color and range anywhere from light tan to black. They come in different sizes, anywhere from a fraction of an inch (or centimeter) to an inch (2.5 cm) in diameter. The telltale feature of seborrheic keratoses is that they look like they have been pasted on the skin or just stuck on it. They may look like a dab of warm brown candle wax that dropped on the skin. Almost everybody eventually develops at least a few seborrheic keratoses since they tend to become more common and more numerous with age. They are sometimes referred to as "barnacles of old age." The development of seborrheic keratoses is sometimes triggered by pregnancy, estrogen therapy or certain medical conditions.
Seborrheic keratoses are most often found on the chest or back but can be found on the scalp, face, or neck or almost anywhere on the body. When they first appear, the growths usually begin one at a time as small rough bumps. Eventually they thicken and develop a rough, warty surface. Although seborrheic keratoses may first appear in one spot and seem to spread to another, they are not catching. As people age they may simply develop a few more. These growths may be unsightly, especially if they begin to appear on the face. They can get irritated by clothing rubbing against them. Because they may grow larger over the years, removal is sometimes recommended especially if they get irritated and bleed easily. A seborrheic keratosis may turn black and may be difficult to distinguish from a skin cancer. Sometimes such a growth must be removed and studied under a microscope to determine if it is cancerous or not.
Salves, ointments or medication can neither cure nor prevent seborrheic keratoses. Most often seborrheic keratoses are treated by one of three methods: