When a glabellar dermoid cyst is not the whole story: the significance of MRI in excluding intracranial segments.
Rebekka Wiedenhoefer, Ursula Feige, Mukesch Shah et al.
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Case in brief
A 14-month-old boy underwent removal of a glabellar dermoid cyst considered extracranial. He remained asymptomatic, but surveillance MRI 10 months later showed a right frontal parasagittal intracranial lesion, subsequently resected and diagnosed as an epidermoid cyst. Retrospective review suggested that a very small intracranial component might have been faintly visible on the initial MRI, although it was not recognized at the time. The report’s review also noted that intracranial extension occurs particularly in craniofacial midline lesions, but is not limited to them.
What made this case unusual
An intracranial epidermoid cyst was detected after surgery for a glabellar dermoid classified as extracranial; the subtle component was not recognized on the initial MRI despite imaging having been performed.
Diagnostic / clinical pearl
A negative or apparently extracranial preoperative MRI interpretation may not exclude a subtle deeper component. Carefully assess lesion extent and consider imaging follow-up when operative findings raise concern for intracranial extension.