側頭骨錐体部に発生した類上皮腫の2症例

Two Cases of the Epidermoid on the Petrous Bone

I．はじめに

　類上皮腫は全頭蓋内腫瘍の1.3％を占め^5），ほとんどが硬膜内に発生し好発部位は小脳橋角部・傍鞍部である．頭蓋骨板間層などの硬膜外からの発生は全類上皮腫の約10％と少なく，約半数が側頭骨錐体部に発生する．今回，末梢性顔面神経麻痺で発症した側頭骨錐体部類上皮腫の稀な2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．

Epidermoids known as cholesteatomas, are congenital benign tumors and originate in the embryonic ectoderm. They account for 1.3% of all intracranial tumors. They are often found in the cerebellopontine angle and the paraseller region, but rarely in the petrous portion of the temporal bone. Epidermoids of the petrous bone tend to slowly present progressive facial palsy and hearing disturbance.

In this article, two cases of epidermoids involving the petrous bone are reported. A 55-year-old male pre-sented left facial palsy, left hearing disturbance and decreased gustation in the left side of the tongue. MRI revealed a non-enhanced mass on the petrous portion of the left temporal bone, and bone-window CT showed bone destruction in the same region (Case 1). A 71-year-old female was aware of left facial palsy and left hearing loss for 15 years. MRI showed a non-enhanced mass on the petrous bone, and bone-win-dow CT demonstrated extensive bone erosion of the petrous bone and the middle cranial fossa (Case 2). In both cases, total removal was performed via the middle cranial fossa approach. Both tumors existed ex-tradurally and had pressed against the genicurate ganglion of the facial nerve. The facial palsy of the for-mer case recovered 12 months after surgery.

We discuss the problems of diagnosis and treatment of epidermoids of the petrous bone.