An immunohistochemical study of cytokeratins (CK) in a case of trichilemmal carcinoma (TLC). CK expression showed the presence of CK 1, 10, 14 and 17, suggesting that TLC differentiates toward follicular infundibulum. In a comparison of CK expression between TLC and trichilemmoma, the absence of CK 15 and 16 in TLC may be related to transformation from trichilemmoma to TLC. Trichilemmal carcino...