Primary central nervous system lymphoma (PCNSL) is an onco-hematological malignancy affecting the central nervous system (CNS), meninges or eyes. It is a rare pathology, forming part of the spectrum of diffuse large B-cell lymphomas (DLBCL). PCNSL is currently estimated to account for up to 1% of lymphomas, 4–6 % of all extra nodal lymphomas and about 3% of all central nervous system (CNS) tumors [1].

Prognosis and treatment of this disease have evolved considerably in recent years, in favor of prolonging patient survival despite its aggressive nature. Today, IV high-dose methotrexate plays a central role in the treatment of this pathology, and may be accompanied by other systemic chemotherapies, and possibly encephalic radiotherapy [1], [2]. Innovative treatments can also be considered an evolution of the current standard of care. CAR-T cell therapy has shown promising results in treating DLBCL and could offer a new approach to PCNSL treatment [3].

Diagnostic suspicion is mainly based on clinical presentation, prompting the performance of injected MRI brain imaging. To date, confirmation of this diagnosis remains, in most cases, based on anatomopathological data following a brain biopsy (stereotactic or neuronavigation-assisted).

However, several biological and cytological markers can be used to characterize this pathological entity. Immunophenotyping of cerebrospinal fluid (CSF) lymphocytes, in addition to cytological studies, can reveal clonal B lymphoma cells. Immunological markers such as interleukins (IL) 6 and 10, and their levels, are important diagnostic elements in patients with an atypical radiological presentation and/or a lesion that is difficult to access by brain biopsy [4]. In addition, indirect information such as radiological criteria or ophthalmological damage can be used to aid diagnosis.

This observational study will retrospectively describe the diagnostic features of patients newly diagnosed and treated for a primary cerebral lymphoma at the CHRU de Tours from 2017 to 2023. We will study the results of performed complementary examinations such as MRI characteristics; ophthalmological test; anatomopathological data obtained through brain biopsy and biomarker results obtained by lumbar puncture or vitrectomy (cytology, immunophenotyping and interleukin assays).