免疫抑制状態に合併したEpstein-Barr Virus Associated Malignant Lymphomaの1例

Epstein-Barr Virus-Associated Malignant Lymphoma in an Immuno-deficiency Patient : a case report

I．はじめに

　免疫不全状態にある患者にはしばしば悪性リンパ腫が合併する^1,5,6）．免疫不全には，先天性免疫不全症，臓器移植に際しての免疫抑制療法によって生じる免疫不全症，腫瘍等に対する化学療法に合併する免疫不全症，そしてAquired ImmunoDeficiency Syndrome（AIDS）などが含まれる^7）．欧米ではAIDS患者が多いため，これに伴う悪性リンパ腫に遭遇する機会も多いが，日本ではAIDS症例が少ないため，脳神経外科医が免疫不全に伴う悪性リンパ腫に遭遇する頻度は少ない．しかしながら，日本でも移植医療は活発に行われており，今後免疫抑制剤を使用する機会はさらに増加すると思われる．今回われわれは，骨髄移植に際する免疫抑制療法によって生じた悪性リンパ腫の症例を経験したので，文献的考察を加え報告する．

Human infection with Epstein-Barr (EB) virus occurs commonly, and EB virus exists in the B cell as acryptic infection. Infected B cells become immortal by expressing both the EBNA2 and the LMP1 genesderived from the Bi virus. Under normal condition of cellular immunity, the T cells recognize the EBNA2and LMP1 as foreign proteins and attack the immortal B cells. However, under the condition of immuno-deficiency, the immortal B cells can proliferate and form a tumor. We report a case of malignant lymphomaassociated with immuno-deficiency which may correspond to this mechanism.

A 33-year-old woman, who bad an immuno-deficiency due to treatment for leukemia, had a progressinghemiparesis on her left extremities. Magnetic resonance imagings revealed a ring enhanced tumor withmassive brain edema in the right fronto-parietal lobe. Stereotactic biopsy was performed and histologicalexamination showed it to be a malignant lymphoma. The tumor cells were positive for L26 cellmarker), CD79a, LMP1, and EBNA2. Tbev were negative for UCHL-1 and CD3 (T cell marker). Accord-ing to these results, this lymphoma was caused by EB virus infection under the condition of immuno-de-ficiency.