A rare case of nonenhancing primary central nervous system lymphoma mimic multiple sclerosis

Primary central nervous system lymphoma (PCNSL) is reported to have increased in the last decades. Early diagnosis is crucial for proper management of this tumor. We report a case of a 48-year-old man who was initially diagnosed with multiple sclerosis. Magnetic resonance imaging of the brain revealed multiple lesions with hypersignals in the bilateral basal ganglia and brain stem in T2-weighted image and non-enhancement, while positron emission tomography showed a low uptake of ¹⁸F-fluorodeoxyglucose in the affected brain, indicative of demyelination. However, this individual was correctly diagnosed with PCNSL after biopsy and further histological analysis. Primary central nervous system lymphoma must be considered even when nonenhancing, diffuse lesions are seen on MRI. A visible tumor on imaging is essential to ensure an early brain biopsy and histological diagnosis.Primary central nervous system lymphoma (PCNSL) accounts for 3.3% of all brain tumors.1 Primary central nervous system lymphoma in immunocompetent patients is non-Hodgkin lymphomas of germinal B-cell origin in the vast majority of cases, which arise from the brain, spinal cord, cerebrospinal fluid (CSF), or eyes in the absence of systemic disease.1,2 Because of its ambiguous clinical manifestation, neuroradiographic, and CSF cytology, PCNSL can be easily misdiagnosed. Our objective in presenting this particular case is to highlight that PCNSL should be considered even when non-enhancing, diffuse lesions are seen on MRI.