Related Disorders List

Information on the following diseases can be found in the Related Disorders section of this report:

• Malignant Melanoma
• Pigmented Basal Cell Carcinoma

Symptoms

Symptoms of Seborrheic Keratosis are limited to discolored skin lesions that appear to be "stuck on" the skin surface. These patches may appear suddenly, may vary in size, and tend to grow slowly. They may be round or oval-shaped, and vary in color from tan, yellowish-brown to black. They may be widespread over the trunk, back, and/or shoulders. Some may be large enough to be called “giants” while others may be limited to small areas of the temples or cheeks. The skin lesions may also be waxy, scaling or crusted. They tend to become darker and larger with age.

Causes

The exact cause of Seborrheic Keratosis is not known although researchers believe some forms may be inherited as a dominant trait. Human traits including the classic genetic diseases, are the product of the interaction of two genes for that condition, one received from the father and one from the mother. In dominant disorders, a single copy of the disease gene (received from either the mother or father) will be expressed "dominating" the normal gene and resulting in appearance of the disease. The risk of transmitting the disorder from affected parent to offspring is 50% for each pregnancy regardless of the sex of the resulting child.)

Affected Populations

Seborrheic Keratosis predominately affects middle aged individuals, although in very rare cases, it can be present at birth.

Related Disorders

Symptoms of the following disorders can be similar to those of Seborrheic Keratosis. Comparisons may be useful for a differential diagnosis:

Malignant Melanoma is a type of skin cancer characterized by rapid growth of the cells which form normal skin pigmentation (melanin). They can appear on any part of the body and, in the early stages, the lesions may resemble those found in Seborrheic Keratosis. A skin biopsy may be necessary to confirm the diagnosis.

Pigmented Basal Cell Carcinoma is characterized by localized, slow growing skin nodules which rarely spread to other parts of the body. These small, shiny and firm growths are associated with skin or hair follicle cells. Ulcerated, crusted lesions, and flat, scar-like plaques with hardened skin may also develop.

Standard Therapies

Since Seborrheic Keratosis is not a form of skin cancer, treatment is not essential and removal of lesions is usually performed only to enhance comfort and/or cosmetic appearance. Treatment of Seborrheic Keratosis consists of removal of the skin lesions by scraping (curettage), sealing off blood vessels or destruction of lesions (electrodessication) with local anesthetic, shave excision, or freezing with CO2 snow or liquid nitrogen. Trichloroacetic acid may be used to eliminate lesions. Dermabrasion removal may also be performed. In most cases, scarring is not associated with removal of these skin lesions.

References

Sowden JM, et al., The management of seborrheic keratoses by general practitioners, surgeons and dermatologists. Br J Dermatol. 198;139:348-49.

Pariser RJ., Benign neoplasms of the skin. Med Clin North Am. 1998;82:1285-1307, v-vi.

Lemperle G., Scratching off senile warts. Plast Reconstr Surg. 1998;101:546-47.

Marks, R, et al., Who removes pigmented skin lesions? J Am Acad Dermatol. 1997;36(5 Pt 1):721-26.