Radiologic mimicry: CNS lymphoma mimicking meningioma on CT and MRI

Meningiomas, which represent the majority of primary intracranial tumours, are characterized by typical imaging features such as a well-defined shape and homogeneous contrast enhancement. However, clinical practice necessitates the inclusion of rare neoplasms capable accurately mimicking them in the differential diagnosis. This study aims to present in detail the case of a 69-year-old male with a tumour in the cerebellar vermis, which on magnetic resonance imaging (MRI) demonstrated strong, homogeneous contrast enhancement, initially suggesting a meningioma. Crucial atypical imaging elements that challenged this diagnosis were the lesion’s irregular shape, its poor demarcation from the surrounding brain tissue, and significant restricted diffusion on diffusion-weighted imaging (DWI) sequences. The decisive clinical evidence, however, was the spectacular regression of the volume of the tumour following empirical corticosteroid therapy, which strongly suggests lymphoma of the central nervous system. Final confirmation of a disseminated lymphoproliferative process was obtained through the biopsy of a concomitant kidney lesion, with histopathological results consistent with diffuse large B-cell lymphoma. This case vividly illustrates radiologic mimicry in neuro-oncology and underscores the critical importance of analyzing subtle, atypical imaging features and the response to steroid therapy. The conclusion drawn from this report is the necessity of including SCNSL – secondary central nervous system lymphoma – in the differential diagnosis of every dural-based mass, which prevents diagnostic errors and an unnecessary, burdensome craniotomy in favour of implementing appropriate systemic treatment.