Seborrheic keratoses are thickened areas of skin seen in adults.
Although they can occur anytime after puberty, almost every elderly human has these and they increase in number with age. Some families have an inherited tendency to grow multiple lesions. Dark-skinned people are less affected a variant seen in blacks is called dermatosis papulosa nigra.
They start as light brown to skin-colored, flat areas, which are round to oval and of varying size (usually less than a half inch, but sometimes much larger). As they grow thicker they may become dark brown to almost black with a “stuck on” appearance. They don’t occur on palms, soles, and mucous membranes (eg, in the mouth or rectum). They do not go away. They do not turn into cancers.
No treatment is needed unless there is irritation from friction or for cosmetic reasons. Removal can be accomplished with freezing (cryosurgery), scraping (curettage), burning (electrocautery),lasers, or with acids.