Periorbital Dermoid Cyst With Unique Trichilemmal Differentiation.

The authors describe a 4-year-old girl presenting with a 2-year history of a superomedial eyelid "bump" that appeared cystic on MRI. The clinical diagnosis was dermoid cyst, possibly of conjunctival origin. Following excision, histology showed a cyst that contained keratin and lanugo hairs in its lumen with sebaceous glands and chronic inflammation in its fibrous wall. An unanticipated finding was the presence of a trichilemmal (pilar) variety of epithelial lining that stained positively for calretinin, an immunostain that identifies trichilemmal epithelium. To the authors' knowledge this is the first case of a dermoid cyst with trichilemmal lining. This study was conducted in compliance with the rules and regulations of the Health Insurance Portability and Accountability Act and in conformity with the Oslo declaration. (C) 2016 by The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc., All rights reserved.

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