What are variants 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

Variants include the following:

  • Dermatosis papulosa nigra: These lesions affect the face, especially the upper cheeks and lateral orbital areas. They are small, pedunculated, and heavily pigmented with a minimal keratotic element. The onset of these lesions generally is earlier than that of ordinary seborrheic keratoses. These lesions appear to be caused by a nevoid developmental defect of the pilosebaceous follicles. Histologically, they show irregular acanthosis and hyperkeratosis.

  • Stucco keratosis: Some adults develop large numbers of superficial gray-to-light brown flat keratotic lesions favoring the dorsa of the feet, the ankles, and the dorsa of the hands and forearms. Some investigators think these stucco keratoses are a variant of seborrheic keratosis. Histologically, horn cysts are not observed and a regular spiky papillomatosis with a loose lamellated hyperkeratosis capping the epidermis is prominent.

  • Melanoacanthoma: Melanoacanthoma is a deeply pigmented seborrheic keratosis in which an acanthotic proliferation of large dendritic melanocytes is identified. It probably represents a concomitant proliferation or activation of the dendritic melanocytes and epidermal cells.

  • Polypoid lesions: A clinical variant of the typical seborrheic keratosis is small polypoid lesions around the neck, under the breast, or in the axillae. They are commonly called skin tags, but different from smooth skin tags, these lesions have a furrowed rough surface. They have a predilection for points of chronic trauma.


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