A seborrheic keratosis (SK) is a benign (non-cancerous) skin condition that appears as a waxy brown, black, or tan growth. A seborrheic keratosis is one of the most common skin growths in older adults. While it's possible for one to appear on its own, multiple growths are more common. Seborrheic keratosis often appears on the face, chest, shoulders, or back. It has a waxy, scaly, slightly elevated appearance. No treatment is necessary. If the seborrheic keratosis causes irritation, it can be removed by a doctor.