Primary Multi-focal Central Nervous System Lymphoma Masquerading as a High-grade Insular Glioma - A Rare Case Report

Primary central nervous system lymphoma (PCNSL) is a rare brain tumor, typically arising in deep cerebral structures. We report an unusual case of PCNSL involving the insular cortex and perisylvian region in a 70-year-old immunocompetent female, initially misdiagnosed as a high-grade glioma based on imaging. Magnetic resonance imaging revealed a large heterogeneous lesion with mass effect, leading to surgical resection. Histopathology and immunohistochemistry confirmed a high-grade B-cell lymphoma with double expression of BCL2 and BCL6. This case highlights the diagnostic challenge posed by atypical PCNSL presentations mimicking gliomas, emphasizing the critical role of tissue diagnosis. Surgical resection, although uncommon in PCNSL, was essential due to lesion size and mass effect. The awareness of such rare presentations facilitates the accurate diagnosis and timely lymphoma-directed therapy.