LAUSR

BACKGROUND Primary central nervous system lymphoma (PCNSL) is a relatively common tumor of the central nervous system. Although PCNSLs generally arise from the parenchyma, lymphomas arising primarily from the dura are termed dural lymphomas (DLs). Mucosa-associated lymphoid tissue is the most unique histological feature of DLs. Because of its rarity, the clinical characteristics of and treatments for DL have not been fully elucidated to date. CASE DESCRIPTION A 31-year-old man with no past medical history presented with numbness in his left upper limb. Magnetic resonance imaging revealed a dural-based tumoral lesion and cervical lymphadenopathies. The lesion was diagnosed radiologically as a meningioma, and tumor resection was planned. However, an intraoperative pathological diagnosis showed neoplastic lymphocytes, and the planned total tumor resection was halted. Histologically, the tumor was characterized by areas of poorly defined follicular architecture consisting of medium and large centroblasts. These tumor cells were immunohistologically positive for CD10 and CD20 and negative for B-cell lymphoma (BCL) 2 and BCL6. Fluorescence in situ hybridization did not show evidence of an Immunoglobulin H/BCL2 fusion. The lesion was subsequently diagnosed as a pediatric-type follicular lymphoma (PTFL). Six cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone) plus 2 cycles of rituximab were administered. The patient showed no evidence of relapse at 12 months after diagnosis, and follow-up was ongoing at the time of this report. CONCLUSIONS This very rare case of DL was originally diagnosed as a PTFL. The tumor could be treated by immunochemotherapy alone.