Multiple presentations: a single pathology, primary central nervous system lymphoma (PCNSL). A multicenter study.

BACKGROUND: Primary central nervous system lymphoma (PCNSL) is an uncommon extranodal non-Hodgkin lymphoma confined to the brain, spinal cord, leptomeninges, and eyes. Despite its characteristic histology, its neuroimaging appearance is remarkably heterogeneous and often mimics other brain tumors or inflammatory diseases. METHODS: We performed a retrospective analysis of patients diagnosed with PCNSL by members of the Mexican Neuro-Oncology Group. Only cases with histopathological confirmation and pre-treatment contrast-enhanced MRI were included. Lesions were classified according to radiological pattern, number, enhancement characteristics, and anatomical location. RESULTS: A total of 133 patients met the inclusion criteria. The mean age was 51 years, and 54.2% were men. Seventeen distinct radiological presentation patterns were identified: snowball (58.2%), lymphomatosis cerebri (2.3%), ghost tumor (3.0%), subdural hematoma–like (0.8%), pachymeningeal (2.3%), Ring lesion (5.3%), intraventricular (1.7%), uveal–meningeal (5.9%), isolated intraocular (3.8%), CLIPPERS-like (1.5%), pseudo–multiple sclerosis (3.8%), pseudometastatic (6.0%), primary meningeal (1.5%), pseudoschwannoma (0.8%), pseudomeningioma (2.3%), pseudoadenoma (0.8%), and spinal cord form (0.8%). Deep or periventricular involvement was observed in more than half of the cases. CONCLUSIONS: PCNSL exhibits a broad spectrum of neuroradiological patterns that may complicate its recognition. Identifying these atypical presentations is essential to avoid diagnostic delays. Imaging alone is insufficient to establish the diagnosis, underscoring the need for histopathological confirmation. To our knowledge, this represents the largest Latin American series describing the neuroradiological heterogeneity of PCNSL.