Seborrheic keratosis

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A seborrheic keratosis is a non-cancerous (benign) skin tumor that originates from cells, namely keratinocytes, in the outer layer of the skin called the epidermis. Like liver spots, seborrheic keratoses are seen more often as people age. The tumors (also called lesions) appear in various colors, from light tan to black. They are round or oval, feel flat or slightly elevated, like the scab from a healing wound, and range in size from very small to more than 2.5 centimetres (1 in) across. They are often associated with other skin conditions, including basal cell carcinoma. Sometimes, seborrheic keratosis and basal cell carcinoma occur at the same location. At clinical examination, a differential diagnosis considers warts and melanomas. Because only the top layers of the epidermis are involved, seborrheic keratoses are often described as having a "pasted-on" appearance. Some dermatologists refer to seborrheic keratoses as "seborrheic warts", because they resemble warts, but strictly speaking...

Read on Wikipedia · Image James Heilman, MD, CC BY-SA 3.0