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Orbital Extension of a Frontal Bone Intradiploic Epidermoid Cyst

Diniz, Stefania B. M.D.*; Chahud, Fernando M.D.; Cruz, Antonio A. V. M.D.*

Ophthalmic Plastic and Reconstructive Surgery: November/December 2019 - Volume 35 - Issue 6 - p e158
doi: 10.1097/IOP.0000000000001358
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*Division of Oculoplastics and Orbit, Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery

Department of Pathology and Forensic Medicine, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil

Accepted for publication February 7, 2019.

The authors have no financial or conflicts of interest to disclose.

Address correspondence and reprint requests to Antonio A. V. Cruz, M.D., Department of Ophthalmology, Hospital das Clínicas de Ribeirão Preto-CAMPUS. School of Medicine of Ribeirão Preto, University of São Paulo, Av Bandeirantes 3900, 14049–900 Ribeirão Preto, São Paulo, Brazil. E-mail: aavecruz.fmrp@gmail.com

A 23-year-old man presented with progressive right proptosis and diplopia (Fig. A). Five years ago, he had undergone a right orbitotomy through the lid crease for excision of an orbital cyst. On examination, his right eye was proptotic (Hertel’s exophthalmometry: 24 mm OD and 16 mm OS) and displaced downward with upgaze movement limitation. His visual acuity was 20/20 OU. MRI revealed a heterogeneous soft-tissue mass in the diploe of the right frontal bone, extending into the orbit through a tortuous bony defect (Fig. B). A coronal approach was employed to unroof the bony canal, allowing complete excision of the cyst (Fig. C). Histopathology of the specimen demonstrated stratified squamous epithelium without skin appendages with abundant layers of keratin debris toward the center of the cyst (Fig. D). The resulting bony defect was repaired with a periosteal flap. The outcome was excellent, with resolution of diplopia and proptosis. Orbital intradiploic epidermoid cysts are uncommon lesions described in the past as “orbital cholesteatomas.” This term is a misnomer because the cyst does not contain cholesterol (chole) nor fat (steato). Because the cyst is filled with keratin, MRI allows a precise delineation of the pathway of the lesion. To prevent recurrence, its intraosseous component must be completely excised.

© 2019 by The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc., All rights reserved.