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Facts about the skin from DermNet New Zealand Trust. Topic index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Seborrhoeic keratoses

Seborrhoeic or seborrheic keratoses are very common harmless skin lesions that appear during adult life. Seborrhoeic keratoses may also be called basal cell papillomas, senile warts or brown warts.

Seborrhoeic keratoses are harmless and rarely or never become malignant.

Despite the name, they do not have sebaceous origin.

What do they look like?

They begin as slightly raised, skin coloured or light brown spots. Gradually they thicken and take on a rough, warty surface. They slowly darken and may turn black. These colour changes are harmless but may result in the lesion looking like a melanoma (a type of skin cancer).

They appear to stick on to the skin like barnacles.

Seborrhoeic keratoses appear on both covered and uncovered parts of the body. There may be one or many of them.

Seborrhoeic keratosis Seborrhoeic keratosis Seborrhoeic keratosis Seborrhoeic keratosis
Seborrhoeic keratosis Seborrhoeic keratosis Seborrhoeic keratosis
Seborrhoeic keratoses

What causes seborrhoeic keratoses?

The cause of seborrhoeic keratoses is not known. The name is misleading, because they are not limited to a seborrhoeic distribution (scalp, mid-face, chest, upper back) as in seborrhoeic dermatitis, nor are they formed from sebaceous glands as is the case with sebaceous hyperplasia.

Seborrhoeic keratoses are considered degenerative in nature, appearing as part of the skin aging process. As time goes by, seborrhoeic keratoses become more numerous. Some people inherit a tendency to develop a very large number of them.

They are not generally caused by exposure to the sun, although they can follow sunburn or other irritating skin conditions including dermatitis.

Skin cancers are sometimes difficult to tell apart from seborrhoeic keratoses, so if you are concerned or unsure about any skin lesion consult your doctor.

Very rarely, eruptive seborrhoeic keratoses may denote an underlying internal malignancy. The syndrome is known as the sign of Leser-Trelat.

Other types of seborrhoeic keratosis

Variants of seborrhoeic keratoses include:

Stucco keratosis
Stucco keratoses
Dermatosis papulosa nigra
Dermatosis papulosa nigra
Irritated seborrhoeic keratosis
Irritated seborrhoeic keratosis
Benign keratoses

What is the treatment for seborrhoeic keratoses?

Seborrhoeic keratoses can easily be removed. The usual reason for removing a seborrhoeic keratosis is your wish to get rid of it. For example it may be unsightly, itch or rub against your clothes. Occasionally your doctor may recommend its removal because of uncertainty of the correct diagnosis.

Methods used to remove seborrhoeic keratoses include:

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If you have any concerns with your skin or its treatment, see a dermatologist for advice.