[Epstein-Barr virus-associated malignant lymphoma in an immuno-deficiency patient: a case report]

Human infection with Epstein-Barr (EB) virus occurs commonly, and EB virus exists in the B cell as a cryptic infection. Infected B cells become immortal by expressing both the EBNA2 and the LMP1 genes derived from the EB virus. Under normal condition of cellular immunity, the T cells recognize the EBNA2 and LMP1 as foreign proteins and attack the immortal B cells. However, under the condition of immunodeficiency, the immortal B cells can proliferate and form a tumor. We report a case of malignant lymphoma associated with immuno-deficiency which may correspond to this mechanism. A 33-year-old woman, who had an immuno-deficiency due to treatment for leukemia, had a progressing hemiparesis on her left extremities. Magnetic resonance imagings revealed a ring enhanced tumor with massive brain edema in the right fronto-parietal lobe. Stereotactic biopsy was performed and histological examination showed it to be a malignant lymphoma. The tumor cells were positive for L26 (B cell marker), CD79a LMP1, and EBNA2. They were negative for UCHL-1 and CD3 (T cell marker). According to these results, this lymphoma was caused by EB virus infection under the condition of immuno-deficiency.