Spectrum of Neuroimaging Findings in CNS Lymphoproliferative Disorders

Central nervous system (CNS) lymphoproliferative disorders comprise a heterogeneous group of rare entities that present major diagnostic and therapeutic challenges. Primary CNS large B-cell lymphoma (LBCL) is the most common form and the second most frequent primary CNS tumor after gliomas. The 5th edition of the World Health Organization Classification of Hematolymphoid Tumours introduced updated terminology, including primary LBCL of immune-privileged sites and lymphomas arising in immunodeficiency/dysregulation, along with less common variants such as intravascular large B-cell lymphoma, lymphomatoid granulomatosis, lymphomatosis cerebri, secondary CNS lymphoma, mucosa-associated lymphoid tissue (MALT) lymphoma of the dura, and T-cell/NK-cell lymphomas. Immune status, Epstein–Barr virus association, and imaging features may assist differentiation, although biopsy remains essential for definitive diagnosis. On MRI, lesions are typically periventricular or involve the basal ganglia, showing low T2 signal intensity, restricted diffusion, and intense enhancement. Spectroscopy demonstrates elevated choline/N-acetylaspartate ratios with lipids, and perfusion is generally lower than in other neoplasms. Corticosteroid administration before biopsy should be avoided due to potential cytolysis of tumor cells. Major differential diagnoses include glioblastoma, metastases, demyelinating lesions, and infections such as toxoplasmosis, fungal abscess, and tuberculosis. Treatment may cause neurotoxicity and immunosuppression, predisposing patients to opportunistic infections.