小脳橋角部に発生したmeningeal melanocytomaの1例

A Case of Meningeal Melanocytoma in the Cerebellopontine Angle

Ⅰ．はじめに

　頭蓋内発生のmeningeal melanocytomaは2005年までに31例しか報告がないなど珍しい腫瘍であり，その中でも小脳橋角部での発生は極めて稀少である^4,5)．今回，われわれは小脳橋角部に発生したmeningeal melanocytomaの1例を経験したので，文献学的考察を加え報告する．

　Meningeal melanocytomas are uncommon intracranial tumors and extremely rare in the cerebellopontine angle (CPA). The tumors are generally considered to be benign because they lack malignant features in histological examination,but several literatures describe malignant behavior of the tumors such as high frequency of local recurrence,malignant transformation with leptomeningeal seeding. We describe a case of meningeal melanocytoma in the CPA and discuss the features of the tumor.

　The case was a 43-year-old woman with a right CPA exta-axial mass suffering from vertigo and nausea. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a mass in the right CPA. The mass was hyperintense on T1-weighted images and hypointense on T2-weighted images. Surgical removal was done and pathological diagnosis was made as meningeal melanocytoma. Twenty months after the first surgery,MRI revealed local recurrence of the tumor and subtotal resection was performed.