Abstract: Gan Zhonghua, Tang Bo, Wang Hongfei, Gao Jie Department of Pathology, Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou 646000, Sichuan, China Corresponding author: Gan Zhonghua, Email: ganzh868@126.com 【Abstract】 A 67-year-old male patient presented with a plaque on the top of the head for more than 1 year. Physical examination showed an annular pale red plaque sized about 1.5 cm × 1 cm on the top of the head. It had a depressed center and papule-like elevated faint yellow boundaries, and there was no hair on the surface of the lesion. Histopathologic examination revealed milder epidermal hyperplasia, a small area of epidermal depression, confluence and hyperplasia of multiple sebaceous glands in the dermis, many keratinous cysts and funicular basophilic epithelial cells surrounded by hyperplastic collagen fibers in the superficial dermis. Immunohistochemical study showed positive staining for CD34（hair mesenchymal cells）, epithelial membrane antigen （EMA）, cytokeratin 20 （CK20）, but negative staining for bcl-2, P53, CD56 and collagen Ⅳ, with the proliferation index Ki-67 of 2% - 5%. Based on the pathological results, the patient was diagnosed with desmoplastic trichoepithelioma complicated by sebaceous hyperplasia.

Key words: Sebaceous gland diseases, Desmoplastic trichoepithelioma