小脳に原発し脳神経に沿って進展した悪性リンパ腫の1例

Primary Central Nervous System Malignant Lymphoma Originating from the Cerebellum and Extending along the Lower Cranial Nerves

I．はじめに

　中枢神経系原発性悪性リンパ腫（primary cen-tral nervous system malignant lymphoma；PCN SML）は近年，後天性免疫不全症候群（acquired immunodeficiency syndrome；AIDS）の増加とともに急増しており，種々の報告，研究がなされている．しかし本邦ではAIDSの発生率が欧米に比べて低いにもかかわらず，PCNSMLの発生は増加している^1）．PCNSMLは一般的に脳実質から発生するとされており実質外に発育するものはきわめて稀で，髄外にPCNSMLを認めた例は，発育形式を問わず小脳橋角部に発生したものも含めこれまで14例が報告されているに過ぎない^10）．今回われわれは，小脳半球に原発し下位脳神経に沿って髄外に進展，発育した稀なPCNSMLの1例を経験したので文献的考察を加え報告する．

We report a case of primary central nervous system (CNS) malignant lymphoma of the central nervous system originating from the cerebellum and growing along the lower cranial nerves. A 67-year-old woman presented with hoarseness, vertigo, nausea, and vomiting. Gd-DTPA enhanced MRI showed a homogene-ous enhanced mass lesion extending from the cerebellum to the medulla oblongata around the jugular fora-men on the right side. Although pre- and intra-operative diagnosis had been schwannoma, histopathologic-al examination revealed a B-cell, diffuse malignant lymphoma. The growth pattern of malignant lymphoma in the present case, which extended extra-axially, is considerd to be rare. We discuss here the growth pat-terns and difficulties of diagnosis of primary CNS malignant lymphoma in this area.