Abstract

Trichilemmoma is a hamartomatous proliferation derived from the outer root sheath of the hair follicle, first described by Headington and French in 1962. Trichilemmoma commonly occurs on the face and nose, followed by eyebrow and eyelids being the most common locations. Trichilemmoma has a variable clinical appearance thus mimicking other benign or malignant skin lesions such as basal cell carcinoma (BCC) or squamous cell carcinoma (SCC). A histological variant, desmoplastic trichilemmoma (DT) is characterized by a central area of desmoplasia, thus necessitating histopathological examination to rule out invasive lesions. Due to clinical and histopathological resemblances between trichilemmoma and other skin malignancies, making the correct diagnosis of trichilemmoma can sometimes be challenging. CD 34 is a critical immunostain which has diagnostic value in differentiating DT from SCC and BCC. The association of SCC and BCC with DT has been described in terms of diagnostic challenges and histological and immunohistochemical appearance, but no correlation has been made thus far in literature. Herein, we present a case of SCC arising in DT. The purpose of this study is to evaluate the association between SCC and DT and make clinicians aware of the possibility of DT to serve as a precursor to SCC and the implications for treatment and prognosis.

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