Seborrheic keratosis.Seborrheic keratosis is a benign proliferation of the epidermis. Many names are applied to this lesion (senile wart, melanoacanthoma), but seborrheic keratosis is the most widely accepted. Considered one of the most common skin lesions, it usually occurs in older patients; there is no predilection for either sex. The lesions appear "stuck on" the skin, usually on sun-exposed skin. They can be tan, brown, or black. Frequent irritation or friction may cause a papule/nodule to become red and scaly and result in a clinical misdiagnosis. Many variants of seborrheic keratosis are recognized clinically and histologically, but they have no management implications. Seborrheic keratosis is considered to represent a clonal expansion, so the lesion qualifies as a neoplasm. The keratinocytes proliferate to form a well-defined endophytic endophytic /en·do·phyt·ic/ (en?do-fit´ik) 1. pertaining to an endophyte. 2. growing inward; proliferating on the interior of an organ or structure. , flat, or exophytic nodule of tumor cells. There is usually a well-defined border with the underlying dermis. Broad sheets of small to medium cells are separated by horn cysts (figure, A). Surface keratinization keratinization /ker·a·tin·i·za·tion/ (ker?ah-tin?i-za´shun) conversion into keratin. ker·a·tin·i·za·tion n. The conversion of squamous epithelial cells into a horny material, such as nails. (hyperkeratosis hyperkeratosis /hy·per·ker·a·to·sis/ (-ker?ah-to´sis) 1. hypertrophy of the stratum corneum of the skin, or any disease so characterized. 2. hypertrophy of the cornea. ), papillomatosis (papillary projections), or acanthosis (wide rete pegs) are common features of seborrheic keratosis. Different patterns or histologic features result in variants, such as reticulated reticulated /re·tic·u·lat·ed/ (-lat?ed) reticular. reticulated reticular. , pigmented (figure, B), clonal, irritated, hyperkeratotic, and flat. Occasionally, these benign tumors need to be separated from verruca vulgaris (wart), solar lentigo lentigo /len·ti·go/ (len-ti´go) pl. lentig´ines [L.] a flat brownish pigmented spot on the skin, due to increased deposition of melanin and an increased number of melanocytes. , squamous cell carcinoma squamous cell carcinoma n. A carcinoma that arises from squamous epithelium and is the most common form of skin cancer. Also called cancroid, epidermoid carcinoma. , and melanoma, but separation is usually straightforward, relying on deeper levels cut into the block rather than on special studies. Shave biopsy, electrodessication, or cryotherapy result in cure. [FIGURES A-B OMITTED] Suggested reading Andrews MD. Cryosurgery for common skin conditions. Am Faro Physician 2004:69:2365-72. Elgart GW. Seborrheic keratoses, solar lentigines lentigines /len·tig·i·nes/ (len-tij´i-nez) plural of lentigo. , and lichenoid keratoses. Dermatoscopic features and correlation to histology and clinical signs. Dermatol Clin 2001 : 19:347-57. Lester D.R. Thompson, MD, FASCP From the Department of Pathology, Woodland Hills Medical Center, Southern California Permanente Medical Group, Woodland Hills, Calif. |
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