A benign skin lesion or non-cancerous tutmor resulting from excessive growth of the top layer of skin cells: Seborrheic keratosis is composed of squamous and basaloid cells that are arranged in various patterns to produce a brown papule, studded with yellow collections of keratotic material giving the sores a greasy appearance.

Seborrheic keratosis is usually found in persons over 30 years old and may be only a few or even numerous.