Intradiploic epidermoid cyst

Case contributed by Hoe Han Guan
Diagnosis certain


Occipital swelling for 2 years, gradual increase in size.

Patient Data

Age: 20 years
Gender: Female

A well circumscribed oval shape mass seen arising from the right occipital skull bone, associated with adjacent bony remodeling. This mass demonstrates isointense to grey matter ( brighter than CSF), hyperintense on T2WI and FLAIR sequences (brighter than CSF on FLAIR sequence). On DWI/ADC map, this mass demonstrates homogenous restricted diffusion. On post contrast administration, this mass does not show enhancement.

No blooming artefact on GRE sequence. It abuts the posterior superior sagittal sinus. No obvious filling defect seen within cerebral venous sinuses to suggest cerebral venous infiltration/thrombosis.

Case Discussion

MR features are suggestive of intradiploic epidermoid cyst. The other less likely differential diagnoses to consider include eosinophilic granuloma and lymphoma.

Surgical resection performed and pathologically proven epidermoid cyst.

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