頭蓋内primary leptomeningeal lymphomaの1例

A Case of Intracranial Primary Leptomeningeal Lymphoma

Ⅰ．はじめに

　中枢神経系原発の悪性リンパ腫は稀であるが，高齢者を主体として増加傾向にある腫瘍の1つである．全国脳腫瘍統計調査によれば，全原発性脳腫瘍の約3.1%を占め²⁾，治療もmethotrexate（MTX）を中心とする化学療法と放射線治療により確立されてきている．その中で，極めて稀な発育様式として脳表の髄膜を主体とし，脳表に沿って拡がるタイプのリンパ腫も報告され，primary leptomeningeal lymphoma（PLML），leptomeningeal lymphomatosisまたはleptomeningeal marginal zone lymphomaなどと呼ばれるものがその範疇に入るものと考えられる^{1,3-5,8-14,17-20)}．報告例が少なく，統一した呼称や分類は確立していないが，現在のところ最も多く使われているPLMLと以下は略する．今回われわれはけいれん発作で発症したPLMLと考えられた1例を経験したため，文献的考察を加え報告する．

　Primary leptomeningeal lymphoma（PLML）is a neoplastic meningitis of lymphomatous origin without parenchymal central nervous system（CNS）disease or a systemic tumor. We report a case of PLML that presented with epileptic seizure, and review relevant literature. A 27-year-old man was brought to the emergency department with an epileptic seizure. Two months later, he was again brought to the emergency department with an epileptic seizure. MRI showed enhanced lesions on the surface of the right cerebellar hemisphere, right parietal sulci, and interhemispheric surface of the frontal lobes. We performed an open biopsy and diagnosed the patient with diffuse large B-cell lymphoma of the leptomeninges on the basis of histological findings. The patient was initially treated with chemotherapy including high-dose methotrexate（MTX). Because remission was not achieved by chemotherapy, the patient was treated with whole-brain radiation therapy. After onset, the patient survived for 2 years without recurrence. PLML is a particularly rare type of primary CNS lymphoma. The outcome of PLML, compared with general primary CNS lymphoma, is reported to be very poor because chemotherapy including MTX is ineffective.