Trichilemmal keratosis. A clinicopathologic and immunohistochemical study of two cases.
Trichilemmal keratosis (TK) is an uncommon epidermal tumor that exhibits a keratinizing surface with the formation of a cutaneous horn and that clinically resembles a hyperkeratotic actinic keratosis. Histologically, there is verrucous hyperplasia of the epidermis with orthokeratotic hyperkeratosis. TK is characterized by abrupt keratinization without formation of a granular cell layer, in the same manner as that in which the outer root sheath keratinizes (trichilemmal keratinization). The epidermis is acanthotic and contains pale-staining keratinocytes. Epithelial lobules and small trichilemmal cysts are connected to the thickened epidermis. We describe the clinical, histologic, and immunohistochemical findings of two cases of TK.
Poblet
E
E
Departments of Pathology, Hospital Universitario de Getafe, Madrid, Spain.
Jimenez-Reyes
J
J
Gonzalez-Herrada
C
C
Granados
R
R
D000368:Aged; D018952:Antigens, CD34 / Q000032:analysis; D005260:Female; D006197:Hair; D006801:Humans; D007642:Keratosis / Q000276:immunology / Q000473:pathology*
D018952:Antigens, CD34