Skin Problems & Treatments Health Center

Seborrheic keratoses are common skin growths that usually cause no symptoms. They are benign, which means they are not cancerous. But they can itch, bleed easily, or become red and irritated when clothing rubs them.

Seborrheic keratoses can grow on any part of the body in clusters or singly. They occur most commonly on the back or chest. They often look like they have been pasted onto the skin. They can be flat or raised and can vary in appearance. Seborrheic keratoses:

• Range in color from white to light tan to black. Most are brown. Some are multicolored.
• Range in size from tiny to larger than 1 in. (3 cm) in diameter.
• Range in texture from waxy and smooth to velvety to dry, rough, and bumpy.
• May have dry scale, which you can easily pick off.
• Can have a surface that crumbles when picked.
• Can be dome-shaped with tiny white or black "horns" growing from the surface.
• Can be in a cluster of different-colored growths.
• Can resemble skin tags (small, soft pieces of skin that stick out on a thin stem).
• Can swell and turn red without apparent cause.
• Slowly grow over time, and seldom go away on their own.

The tendency to have seborrheic keratoses that grow in clusters seems to run in families and may be passed down from parent to child. In rare cases, a sudden growth of many seborrheic keratoses is related to cancer elsewhere in the body.

Several other skin conditions, such as warts and skin cancer, can look like seborrheic keratosis.