Epidermoid rarely appears in the cavernous sinus.

see Interdural dermoid cyst.

A 41-year-old man with left abducens nerve palsy. A round-shaped, low-density lesion on CT was located lateral to the left cavernous sinus with a compressed and thinned lateral wall of the sphenoid sinus.

Part of the tumor capsule and its pearly contents were removed with an intradural subtemporal approach, and an inner membranous layer with cranial nerves and a tumor capsule were seen at the bottom of the tumor cavity. Postoperatively, complete cure was achieved. Reviewing similar cases, 18 cavernous sinus epidermis were found

Extracavernous type in 5;interdural in 10;and intracavernous in 3. The interdural type could be further divided into two subtypes:superficial cavernous sinus and inner membranous types.

Frontotemporal and subtemporal procedures via both intra- and extradural approaches are relatively safe for lesions except for the intracavernous type, because cranial nerves are not located in the lateral wall of the tumor. MRI provides more useful information on cranial nerves and aid in choosing a better treatment strategy ¹⁾.