A Case of Trichilemmal Carcinoma Which Invaded into the Parotid Gland with Perineural Involvement of the Facial Nerve, and Showed Distant Metastasis to the Lung

Abstract

Trichilemmal carcinoma is a rare malignant adnexal neoplasm originating from outer root sheath of hair follicle. It is usually located on sun-exposed, hair-bearing areas of the skin of elderly. Although the tumor may be purely intraepidermal, more commonly it is associated with an invasive component, which may extend to the deep dermis or even into subcutaneous fat. However, involvement of muscular layer or tissue deeper than subcutaneous fat is extremely rare. In general, this tumor appears to have an indolent course. Perineural or perivascular invasion is exceedingly rare. And there are just few cases with local or distant metastasis reported in the literature. We report a case of trichilemmal carcinoma primarily occurring in infraauricular skin with invasion into the parotid gland. It showed perineural involvement of the facial nerve by tumor cells and eventually metastasized to the lung during the period of follow up. Korean J Otorhinolaryngol-Head Neck Surg 2010;53:116-20 Key WordsZZTrichilemmal carcinoma·Lung·Distant metastasis.