A 13‐Year Review of Non‐Diffuse Large B Cell Lymphomas of the Central Nervous System at a Tertiary Hospital: A Case Series Study

ABSTRACT

Non‐diffuse large B‐cell lymphomas (non‐DLBCL) of the central nervous system (CNS) are rare and diagnostically challenging. This study aims to characterize the clinical, radiological, and pathological features of non‐DLBCL CNS lymphomas diagnosed at a tertiary care center over 13 years, highlighting diagnostic pitfalls. A retrospective review was conducted of non‐DLBCL CNS lymphoma cases diagnosed at Sunnybrook Health Sciences Centre, Toronto, from 2010 to 2022. Clinical, demographic, and radiological data were extracted from medical records. Imaging was reviewed by a neuroradiologist, and histopathological slides and molecular data were re‐evaluated by a pathology team. Additional tests were performed to update classifications per the 5th edition of the WHO Classification of Haematolymphoid Tumors. Seventeen cases were identified (11 males, 6 females; age 38–76), compared to 72 DLBCL cases during the same period. Nine cases were extra‐axial and eight intra‐axial. Eight were primary and nine secondary CNS lymphomas. B‐cell lymphomas ( n  = 13) included extra‐nodal marginal zone lymphoma ( n  = 6), follicular lymphoma, mantle cell lymphoma, CLL, intravascular large B‐cell lymphoma ( n  = 2), EBV+ LBCL, and polymorphic PTLD. T‐cell lymphomas ( n  = 4) included PTCL, NOS ( n  = 2), ALK‐negative ALCL, and secondary mycosis fungoides. Imaging revealed four major patterns, and symptoms were largely due to mass effect. This case series emphasizes the considerable heterogeneity of non‐DLBCL CNS lymphomas and the diagnostic challenges they present. It highlights key features that can aid recognition and improve diagnostic accuracy for these rare CNS entities.

Trial Registration: SUN‐5771