Co-existence of Primary Glioma and Lymphoma: An Unusual Case Report.

Composite or collision tumors in the central nervous system can significantly impact disease progression and metastasis, potentially affecting treatment efficacy. Studying the mechanisms associated with these tumors can provide neuro-oncologists with insights into tumor diversity, progression, and aid in the development of novel treatments. We encountered an 84-year-old female with memory disturbance who presented with tumors consistent with wild-type isocitrate dehydrogenase high-grade glioma and low-grade B-cell lymphoma at the same site. Magnetic resonance imaging revealed a solid enhanced mass in the right frontal lobe. A pre-operative suspicion of primary central nervous system lymphoma led to a brain biopsy. Histologically, 2 types of lesions were observed; the first consisted of atypical glial cells with diffuse infiltration and mitoses, positive for glial fibrillary acidic protein and negative for anti-isocitrate dehydrogenase 1 (IDH1)-R132H, characterized by partial amplification of PDGFRA and homozygous deletion of CDKN2A. The second type consisted of small atypical lymphoid positive forCD20, showing immunoglobulin heavy chain(IgH) rearrangement, and minimal invasion of vessel walls while filling the perivascular space. Based on these findings, collision neoplasms of high-grade gliomas and marginal zone B-cell lymphomas were suspected. To our knowledge, this is the first reported co-existence of a glioma and intracranial lymphoma.