自然消失を来した中枢神経系原発悪性リンパ腫の1例

Spontaneous Regression of Primary Central Nervous System Lymphoma : A Case Report

　Ⅰ．はじめに

脳原発悪性リンパ腫は，原発性脳腫瘍の約1％を占め，神経膠芽腫や転移性脳腫瘍と同様に非常に予後の悪い脳腫瘍の1つとして認識されている^10,13)．今回われわれは，MRI上4カ月前は正常であった右小脳に突然出現した異常病変に対し脳生検術を施行した．病理所見および免疫電気泳動法による遺伝子解析の結果，悪性リンパ腫と診断された．その後，MRI上，病変は自然消退し約1年間再発徴候を示さない非典型的な悪性リンパ腫の1症例を経験したため報告する．

　A rare case of primary central nervous system lymphoma that regressed spontaneously as shown on serial cranial magnetic resonance imagings (MRI) is described.

　A 60-year-old woman was admitted to our hospital with a well-enhanced mass lesion in the cerebellum although MRI had demonstrated no abnormal findings 4 months before admission. On admission,She complained of headache,but no neurological deficits were observed. The patient underwent exploratory craniotomy and the tumor was partially removed on February 14. Pathologic examination suspected B-cell type of malignant lymphoma. Postoperative MRI performed on February 23,2001 showed disappearance of the mass lesion without further treatment. Different polymerase chain reaction (PCR) assays detected clonal immunoglobulin heavy chain gene rearrangements in paraffin-embedded tissues diagnosed as B-cell lymphoma. The patient was discharged without any neurological deficits for two weeks and was followed up on MRI. One year after operation,MRI revealed an abnormal finding in the cerebellum without apparent neurological deterioration. Radiation therapy of the whole brain and the local site was carried out with a total dose of 50Gy. MRI demonstrated complete remission of the tumor following radiation therapy. She was admitted again to our hospital with right hemiparesis on May,2003. Subsequently,systemic chemotherapy was carried out. The patient died 2 years and 10 months after her initial presentaion.