Table of Contents

Trichilemmoma – low magnification

LEGEND

Tumor with differentiation of the follicular sheath

  • Lobular proliferation with a sharp demarcation between the keratinocytes of the spinous layer and the paler cells of the trichilemmoma. The cells appear paler because their cytoplasm is filled with glycogen.

  • Broad attachment of the lobular proliferation to the epidermis

  • Basal membrane keratinocytes are arranged in a palisading pattern (as seen in basal cell carcinomas) with thickening of the basement membrane (pink appearance)

Trichilemmoma – verrucous aspect

LEGEND

  • Verrucous surface with hyperkeratosis, papillomatosis, and some hypergranulosis

Trichilemmoma – warty appearance -high magnification

Trichilemmoma – high magnification

LEGEND

Unlike trichilemmoma, clear cell acanthoma is not an endophytic tumor. It is characterized by psoriasiform hyperplasia with clear cells and neutrophils in the stratum corneum.

  • Differentiation into outer root sheath cells that are filled with glycogen