Histology Look-a-like #151
Seborrheic keratosis v Sphynx cat
Seborrheic keratosis is one of the most common skin growths in older adults. It is a brown, black or tan growth that has a waxy, slightly elevated appearance. As a result, the growths have often been referred to by the politically incorrect as ‘senile wart’ or ‘barnacles of the elderly’.
Despite their appearance, seborrheic keratoses are neither cancerous nor transmitted by a virus like warts. However, they can be mistaken for melanoma, and are thus worth getting checked out by a specialist. They are very different from a melanoma. Melanomas involve the uncontrolled division of melanocytes (pigment synthesizing cells) in the epidermis and is a deadly cancer if not caught early enough. Seborrheic keratosis only involves the outer layer of keratinocytes (skin cells) in the epidermis.
Interestingly, and despite the fact that the growths themselves are non-cancerous, an onset of keratoses has been associated with internal malignancies like colon cancer - most likely triggered by a storm of cytokines and/or growth factors released by the growing cancer. This onset of seborrheic keratosis due to cancer is known as Leser-Trélat sign.
(Kilickap and Yalcin, 2007)
The keratoses themselves are normally painless and require no treatment, although they may itch or become irritated by clothing. Some patients as a result may opt to have them removed for comfort or cosmetic reasons.
Kilickap, S., and Yalcin, B., 2007, The sign of Leser-Trélat, N. Engl, J, Med., 356:2184
Pathology Outlines, Hale. C., Non-melanocytic skin tumors