ML-14 LOW INVASIVE APPROACH FOR PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMA TREATMENT INVOLVING RITUXIMAB–METHOTREXATE + PROCARBAZINE + VINCRISTINE AND TRIPLE INTRATHECAL INJECTION

INTRODUCTION Although the treatment outcomes of primary central nervous system lymphoma (PCNSL) with multiple treatment regimens involving high–dose methotrexate (MTX)–based multiagent chemotherapy have improved compared with the outcomes with high–dose methotrexate therapy in recent years, its regimen has not been established. Additionally, it is controversial whether intrathecal (IT) MTX injection can be included in a regimen. Our facilities treat PCNSL with R–MPV (rituximab–methotrexate + procarbazine + vincristine) and triple IT injection (methotrexate + Ara C + prednisolone). Here we report a low invasive approach for PCNSL treatment involving R–MPV therapy and triple IT injection. CASE DESCRIPTION A 58–year–old woman complained of prolonged headache and had undergone a medical checkup at our department. Head computed tomography revealed a mass lesion with edema near the right anterior horn of the lateral ventricle. After being hospitalized, biopsy was performed via a small craniotomy for the mass lesion near the right anterior horn of the lateral ventricle, which was suspected to be PCNSL. Multipurpose Head Frame 2 (Mizuho Co., Ltd.) was used for four points of head fixation. Vertek Biopsy Kit (Medtronic Co., Ltd.) was attached to it, and needle biopsy guided by neuronavigation was performed. Finally, biopsy samples were obtained from the lesion. Changes in the entry and target points could be easily made through the operative procedure, which was performed uneventfully. The diagnosis was B–cell–related lymphoma. Subsequently, an Ommaya reservoir was placed via lumbar puncture on postoperative day 7. Finally, the patient was successfully treated with R–MPV therapy and triple IT injection, thereby avoiding repeated lumbar puncture and reduced pain associated with IT injection. CONCLUSION We have reported the diagnosis of PCNSL with needle biopsy guided by neuronavigation and its treatment with R–MPV therapy and triple IT injection after lumbar Ommaya reservoir placement. This approach was associated with reduced invasion and pain in the patient.