According to Drugs.com, seborrheic keratoses, noncancerous, benign tumors caused by the abnormal growth of skin cells, do not normally require any treatment; however, they can be surgically removed if they become irritated or itchy or if they start bleeding. They do not usually heal on their own.
Drugs.com adds that seborrheic keratoses may have a greasy or waxy aspect and a brown, dark or tan color. They can become crusty or rough in appearance in time. They usually appear on the chest and back; however, they may develop on any part of the body. Their cause is unknown; however, they become more common with age.