Seborrheic keratoses are noncancerous (benign) skin growths that some people develop as they age. They often appear on the back or chest, but can occur on any part of the body. Seborrheic keratoses grow slowly, in groups or singly. Most people will develop at least one seborrheic keratosis during their lifetime.
The appearance of seborrheic keratoses can vary widely. They may be light tan to brown or black. The most common texture is rough, with a bumpy, grainy surface that crumbles easily. However, they also may be smooth and waxy. They usually look like they've been stuck onto the skin. While some are tiny, others grow larger than 3 cm in diameter.
Seborrheic keratoses may be mistaken for warts, moles, skin tags, or skin cancer.