B細胞性悪性リンパ腫による傍腫瘍性辺縁系脳炎の1症例

A Case of Paraneoplastic Limbic Encephalitis Associated with Malignant B cell Lymphoma

はじめに

　傍腫瘍性辺縁系脳炎は，担がん患者に辺縁系障害を示唆する臨床症状で急性または亜急性に発症し，腫瘍の直接浸潤・栄養障害・感染などの明らかな原因がない脳炎・脳症である。肺小細胞癌，精巣癌，胸腺腫などでの報告が比較的多く，悪性リンパ腫に合併した報告は少ない。われわれは亜急性の性格変化・記銘力低下・食行動の変化で発症した，B細胞性悪性リンパ腫による傍腫瘍性辺縁系脳炎の62歳，男性例を経験した。傍腫瘍性辺縁系脳炎では潜在する悪性腫瘍による体重減少を伴う症例が多いが，本例のような体重増加を来した例は注目されておらず，貴重な症例と考えられた。悪性リンパ腫における傍腫瘍性辺縁系脳炎の臨床的特徴を文献例と併せて検討し，考察したので報告する。

Abstract

　We report a case of a 62-year-old man with limbic encephalitis associated with diffuse large B cell lymphoma.　He was hospitalized for the assessment of cognitive disturbance and changes in characteristics.　Neurological examination revealed disturbance of recall and recent memory.　Magnetic resonance (MR) imaging of the brain revealed bilateral atrophy of the medial temporal lobes.　Cerebrospinal fluid (CSF) examination revealed mononuclear pleocytosis and elevated protein levels.　Herpes simplex virus DNA was not detected in the CSF by the polymerase chain reaction.　Immunological investigation of the patient's serum samples showed no evidence of acute infection with herpes simplex virus or cytomegalovirus.　Chest computed tomography (CT) revealed a mass lesion on the right hilum of the lung.　Therefore, tumor resection was performed.　The pathological diagnosis was diffuse large B cell lymphoma.　We diagnosed this patient with paraneoplastic limbic encephalitis.　Chemotherapy was performed, but the patient's clinical symptoms failed to improve.

　We investigated 7 previously reported cases of paraneoplastic limbic encephalitis associated with malignant lymphoma in Japan.　We suggest that an early diagnosis of paraneoplastic limbic encephalitis with progressive symptoms such as changes in characteristics is important.　Early diagnosis and treatment of malignant tumors is desirable to facilitate clinical recovery and improve prognosis.

(Received: April 25,2008,Accepted: September 24,2008)