@article {439636, title = {A Hyalinized Trichilemmoma of the Eyelid in a Teenager.}, journal = {Ophthal Plast Reconstr Surg}, volume = {32}, number = {1}, year = {2016}, month = {2016 Jan-Feb}, pages = {e9-e12}, abstract = {A 16-year-old African American male, the youngest patient to date, presented with a well-circumscribed upper eyelid lesion. On excision, the dermal nodule was contiguous with the epidermis, displayed trichohyalin-like bodies in an expanded outer root sheath, and was composed chiefly of small cellular clusters separated by a prominent network of periodic acid Schiff -positive hyaline bands of basement membrane material. The tumor cells were positive for high molecular weight cytokeratins (CK) 5/6, CK14, and CK34βE12 and were negative for CK7, carcinoembryonic antigen and epithelial membrane antigen. Negative S100, glial fibrillary acidic protein, and smooth muscle actin immunoreactions ruled out a myoepithelial lesion. The Ki-67 proliferation index was \<10\%. The diagnosis was a hyalinized trichilemmoma, contrasting with the more common lobular type. As an isolated lesion, trichilemmoma does not portend Cowden syndrome.}, issn = {1537-2677}, doi = {10.1097/IOP.0000000000000389}, author = {Jakobiec, Frederick A and Stagner, Anna M and Sassoon, Jodi and Goldstein, Scott and Mihm, Martin C} }