Keratosis is a noncancerous benign skin growth that originates in keratinocytes. Like liver or brown spots, seborrheic keratoses are seen more often as people age. In fact, they are sometimes humorously referred to as the "barnacles of old age". The lesions appear in various colors, from light tan to black. They are round or oval, feel flat or slightly elevated (like the scab from a healing wound), and range in size from very small to more than 2.5 centimeters across. They can resemble warts, though they have no viral origins. They can also resemble melanoma skin cancer, though they are unrelated to melanoma
Because only the top layers of the epidermis are involved, seborrheic keratoses are often described as having a "pasted on" appearance. Keratosis often requires several treatments with the skin classic depending on the thickness of the lesion.