What Is a Seborrhoeic Keratosis?

A seborrhoeic keratosis is a benign growth of the outer layer of skin. It is one of the most common skin lesions in adults, and becomes increasingly prevalent with age — by the time people reach their sixties and seventies, most will have at least one, and many will have dozens.

Clinically, seborrhoeic keratoses are often described as looking "stuck on" — as if someone has pressed a blob of wax onto the skin surface. They tend to be well-defined, slightly raised, and can range from pale tan to very dark brown or even black.

They can appear almost anywhere on the body, though they are most common on the trunk, face, and extremities. They do not typically appear on the palms or soles.

Why dermoscopy matters here

With the naked eye, seborrhoeic keratoses are usually straightforward — but not always. Darkly pigmented examples can raise concern for melanoma. Flat variants can resemble solar lentigo or even early melanoma. And irritated or traumatised lesions can lose their classic appearance.

Dermoscopy cuts through this uncertainty. The dermoscopic features of seborrhoeic keratosis are among the most distinctive in all of dermoscopy — a constellation of structures that, when present together, allow confident identification.

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