Proliferating trichilemmal tumour of the eyelid in a 7-year-old girl

Abstract

Proliferating trichilemmal tumours (PTTs) are rare cutaneous adnexal tumours derived from the hair shaft outer root sheath. We are reporting the first case of PTT in a young child. In this case, a 7-year-old girl presented with trichilemmal keratinisation consistent with PTT. The patient was monitored with no signs of recurrence. PTT is a rare tumour occurring primarily in adults and we present this case so that young patients with PTT can be diagnosed and treated appropriately with a painless, mobile, rapidly growing mass on the right upper eyelid. CT imaging showed well-circumscribed, heterogenous mass measuring 1.6 cm with fluid-filled appearance and no tissue invasion. Surgical excision was performed and pathology revealed an unencapsulated, well-demarcated tumour.

Keywords: dermatology; head and neck surgery; otolaryngology / ENT; pathology; plastic and reconstructive surgery.

Figure 1

(A, B) Proliferating trichilemmal tumour.

Figure 2

CT image of showing right preorbital mass measuring 1.6 cm demonstrating predominant fluid density and internal heterogeneous contrast enhancement with no invasion of surrounding structures.

Figure 3

Postoperative photograph.

Figure 4

(A, B) Lower power views of the tumour: the tumour is well demarcated and composed of basaloid cell nests that form multiple irregular lobules. Central spaces and rare hair follicles are noted. (C, D) In the centres of the tumour nests, the basaloid tumour cells are undergoing an abrupt change into keratinised epithelial cells and further transform into amorphous keratin materials. (E, F) Brisk mitosis (white arrows) and moderate nuclear pleomorphism are present (E), and Ki-67 immunostain shows its high proliferative index.