小脳橋角部脂肪腫の1例

Cerebellopontine Angle Lipoma : Case Report

　極めて稀な小脳橋角部脂肪腫の1例を報告する。症例は，47歳女性で，右三叉神経痛と右聴力低下を認めた。CTで，右小脳橋角部にCT値−104HU（Hounsfield units）の低吸収域病変を認めた。病変は，MRI，T1強調画像で高信号に描出された。Dixon法，opposed画像では，病変は描出されず，脂肪により構成されていることがわかった。右後頭下開頭により腫瘍を部分摘出した。腫瘍は，右第7,8神経を巻き込み，第5神経に付着していた。腫瘍と第7,8神経との癒着は強く，易出血性で完全摘出は困難であった。組織学的診断は，脂肪腫であった。自験例も含め，小脳橋角部脂肪腫の臨床症状，放射線学的特徴および治療について，若干の文献的考察を行った。

Intracranial lipomas are rare. Cerebellopontine angle lipomas are extremely rare. We report a case of right cerebellopontine angle lipoma. A 47-year-old woman has been suffering from right trigeminal neuralgia for about 1 year.Neurological examina-tion showed right 5th and 8th cranial nerve dysfunc-tion. MRI demonstrated the high intensity mass lesion at right cerebellopontine angle. The lesion was demonstrated as negative intensity in an opposed image by using Dixon's technique. CT showed the lesion as a very low density area (-104 Hounsfield units). Subtotal removal of the tumor was performed following right suboccipital craniectomy. Pathological diagnosis was lipoma.

We review the literature on this rare tumor and discuss the clinical symptoms, radiological findings and management.We suggest that the operation should be prudently performed for the case with only hearing disturbance because there is a high possibility that hearing disturbance will worsen.