Internal Angular Dermoid Indenting on the Globe: Considerations to Achieve an Optimum Outcome

Angular dermoid cysts are common periorbital tumours of embryonic origin in children and adolescents; and arise along the bony sutures as a result of abnormal ectodermal sequestration during development. Usually present in early childhood, are characteristically small benign and slow-growing lesions. External angular dermoid present in the superotemporal quadrant is more common compared to internal angular dermoid in the superonasal quadrant. We report an unusual case of a large internal angular dermoid cyst indenting the globe in a 3-year-old girl who presented with a left upper eyelid mass at a medial angle since one year of age. There was mild mechanical ptosis but no displacement of the globe. Non-contrast computed tomography image revealed a well-defined rounded cystic lesion (15x14 x19 mm) medially in the extraconal region of the left orbit, indenting on the globe. The cyst was excised completely by anterior orbitotomy through a small superior lid crease incision. Cosmetic outcome after surgery was excellent with equal palpebral aperture height in both eyes.

Usually, mass effects on the globe and surrounding structures are features of deep orbital dermoid; can rarely occur in cases of large anterior periorbital dermoid, as was seen in this case. Early surgical excision is recommended and performed in the majority of cases, particularly to restore facial cosmesis and to avoid pressure effects from large dermoid cysts.