側頭骨錐体部類上皮腫の1例

Diploic Epidermoid on the Petrous Bone:A case report

I．はじめに

　Epidermoidは全中枢神経系腫瘍の約1％を占める^13）が，硬膜外に発生するdiploic epidermoidの頻度はさらに低く，なかでも側頭骨錐体部のdiploic epidermoidは極めて稀とされる^{6,8,10,14,19）}．

　最近，われわれは突発性難聴にて発症した右側頭骨錐体部のdiploic epidermoidの興味ある1症例を経験したので若干の文献的考察を加えて報告する．

An unusual case of a congenital petrous bone epidermoid which resulted in a sudden deafness is re-ported.

The patient was a 25-year-old man who suddenly de-veloped a right deafness and tinnitus. Neurological ex-amination on admission revealed slight hearing disturb-ance in the high sound area. Plain craniogram showed a destructive bone lesion in the middle portion of the petrous bone on the right side. Bone-window CT scan disclosed a bony destructive mass in the petrous bone, and enlargement of the internal auditory canal. The mass lesion was almost isodense on plain CT scan and was not enhanced by contrast media. T1 weighted im-aging of MRI demonstrated an isointense mass in the petrous bone, and T2 weighted imaging demonstrated hyperintensity. Gd-DTPA MRI revealed no enhance-ment. Angiogram did not reveal abnormal findings. Right lateral suboccipital craniectomy was performed to remove the posterior wall of the internal auditory cannal. The tumor existed extradurally originating from the diploe of petrous bone. The tumor appeared pearly and fragile. The pathological examination of the speci-men was diagnosed as epidermoid. The postoperative course was uneventful except for right hearing loss on the 4th postoperative day.

Epidermoid arising in the middle portion of the pet-rous bone is quite rare, so this case was hereby re-ported with some references.