Purpose

A 20-month-old presented to clinic with a swelling on the lateral aspect of the right upper eyelid. His parents reported the mass had been present from birth but had gradually increased in size. He was born at 40+5 via a C-section and his past medical history was unremarkable. There were no concerns with his visual attention or behaviour.

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Methods

On examination, visual acuity was 0.2 unaided (uncrowded Cardiff cards), and orthoptic examination was normal. There was a smooth, well-circumscribed lesion positioned on the right internal orbital rim, which was not particularly mobile. Magnetic resonance imaging of the orbits demonstrated a small, lobulated lesion measuring 8mm by 5mm in keeping with a dermoid cyst, internal to the right frontozygomatic suture. 

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Results

Intraoperatively, a well-circumscribed dermoid cyst was identified and excised intact. On further dissection, a second cystic lesion was visualized deeper to the first, tethered to periosteum. The second cyst was excised, and histology confirmed the diagnosis of two separate dermoid cysts.

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Conclusion

Dermoid cysts are typically unilateral, are usually well-circumscribed, but may have atypical shapes. The dumbbell configuration describes two lobes of the same cyst, separated by a bony canal. However, in this case, both lesions were clearly well-circumscribed, with no adjoining tissue and not bridging bone, representing two discrete cysts. Multiple dermoid cysts are extremely rare, with only two other cases described in the literature. In both of these cases, two cysts were visualized on radiological imaging. In this case, the MRI described only one lesion. Clinicians are alerted to the fact that there may be a second cyst intra-operatively, not identified on pre-operative examination or imaging.

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Additional Authors

First name	Last name	Base Hospital / Institution
Maureen	Dumba	North Middlesex Hospital
Miles	Kiernan	North Middlesex Hospital

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