Dumbbell-shaped intradiploic epidermoid cyst involving the dura mater and cerebellum.

A 55-year-old woman presented with an epidermoid cyst extending to the cerebellum manifesting as headaches and pain in the left eye. Magnetic resonance imaging showed an intradiploic part with ring enhancement and an intracerebellar part. Intraoperative inspection revealed erosion of the occipital bone and defective dura mater. The tumor was located both epidurally and subdurally and the cyst consisted of pearly white keratin. The tumor was totally removed and the patient was discharged with no neurological deficit. The intradiploic part of the tumor formed the body and the intracerebellar part was caused by inflammatory reaction, which resulted in the atypical enhancement of the intradiploic part.