Which histologic findings are characteristic of seborrheic keratosis?

Updated: Oct 14, 2020
  • Author: Arthur K Balin, MD, PhD, FACP; Chief Editor: William D James, MD  more...
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Answer

These lesions are raised above the skin surface, and they show a papillomatous epithelial proliferation containing horn cysts without any tendency toward malignancy. The proliferating cells are epidermal and have a basaloid appearance. The number of epidermal basal cells is greatly increased. The acanthotic pattern (see the images below) is the most frequent, in which a thick layer of basal cells is observed interspersed with pseudo-horny cysts. Invaginations to form keratin-filled pseudocysts are present. Some of these cells contain melanin.

Acanthotic type of seborrheic keratosis. Acanthotic type of seborrheic keratosis.
Higher-power view of the cells in an acanthotic se Higher-power view of the cells in an acanthotic seborrheic keratosis.

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