Desmoplastic Trichilemmoma of the Facial Region Mimicking Invasive Carcinoma

Abstract

Trichilemmoma is a hamartomatous proliferation arising from cells of hair follicle. Its desmoplastic variant simulates an invasive carcinoma. In this tumor, the cell of origin seems to be located in the superficial level of the hair follicle just below the basement membrane at the sebaceous gland level. We present a similar case which presented with an asymptomatic nodular lesion in the region above the upper lip on left side. Fine needle aspiration cytology raised the cytological possibility of a malignancy for which the lesion was excised. On histopathology the lesion was diagnosed as desmoplastic trichilemmoma. The case highlights the difficulty encountered in differentiating a benign adnexal tumor from malignant lesion based on cytology alone. Moreover, the extensive desmoplasia on histopathology raises the suspicion of invasive malignancy which requires to be carefully excluded. The superficial features of trichilemmoma and lack of cellular atypia is a useful diagnostic clue in such a situation. Positivity of CD34 can also be used to differentiate from basal cell carcinomas. The case reported here had a solitary lesion, but follow up is required for development of more lesions or multiple hamartomas in other organs as a part of Cowden's disease.

Desmoplastic Trichilemmoma—A Report of Successful Treatment with Mohs Micrographic Surgery and a Review and Update of the Literature

“…We identified 19 publications worldwide reporting a total of 81 distinct individual cases of DT. 1,[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Epidemiology…”

“…A comprehensive literature review was conducted by searching the PubMed database using the keyword “desmoplastic trichilemmoma.” References to additional publications not indexed in PubMed were also followed to obtain a complete record of published data. We identified 19 publications worldwide reporting a total of 81 distinct individual cases of DT …”

Trichilemmoma of the perioral area – Case report

“…There is a lobular proliferation of small uniform cells to the dermis from the epidermis, and the presence of clear cells containing glycogen is the most notable alteration. [1][2][3][4] The relationship between trichilemmoma and common wart is controversial, and trichilemmomas are actually often clinically diagnosed as warts. On the other hand, areas histologically similar to trichilemmomas are often found in warts.…”

“…28,29 Solitary trichilemmomas should be surgically excised, with a peripheral margin of 2 mm and reaching the fullest depth extent of the tumor. 4,30,31 The differential diagnosis of conventional or desmoplastic trichilemmomas should include other benign or malignant tumors of the skin or cutaneous appendages. However, all these entities have distinctive architectural patterns and, unlike trichilemmomas, do not have clear cells or a thick basement membrane.…”

“…It sometimes exhibits central ulceration as well as keratinization of the epidermal surface, which may be sufficient for the formation of pearls or a cutaneous horn. 3,4 It may also involve other locations, such as the neck, scalp, thoracic skin or vulva. 2,3 It presents a slow, progressive growth, and the evolution over time can vary from months to years, with its diameter rarely exceeding 1 cm.…”