Ventricle-predominant primary CNS lymphomas: clinical, radiological and pathological evaluation of five cases and review of the literature.

Primary central nervous system lymphomas (PCNSLs) are typically intraparenchymal. A subset of PCNSLs predominantly arises in the ventricles, with minimal parenchymal involvement. We review the clinical, radiological, and pathological features of ventricle-predominant PCNSLs (VP-PCNSLs) in 40 previously reported cases and report 5 additional cases. Including all cases of VP-PCNSLs (n = 45), 38% were diffuse large B-cell lymphomas (DLBCL), 11% were Burkitt lymphomas, 7% were MALT lymphomas, 4% were T-cell lymphomas, and 40% were lymphomas, not otherwise classified. VP-PCNSLs show rapid clinical progression. Patients present at a median age of 60.5 years. Unique clinical and radiological features distinguish them from other intraventricular tumors, including advanced age, edema, multifocality, hyperdensity, early and avid post-contrast enhancement, restricted diffusion, and positron emission tomography (PET) hypermetabolism. Including our cases, which were all DLBCL, and all previously reported DLBCL cases (n = 10), 8 of 10 show germinal center B-cell-like (GCB) phenotype, contrasting the high prevalence of non-germinal center B-cell-like (non-GCB) phenotype of parenchymal DLBCL PCNSLs. MYD88 L265P mutation was detected in three of our five cases. Ventricle-predominant PCNSLs are clinically and radiologically distinct, and the DLBCLs may be pathologically distinct. Further recognition of this entity may help to evaluate the role of therapies, possibly including surgical resection.