Primary Central Nervous System B-Cell Lymphoma Presenting with Fluctuating Basal Ganglia and Cortical Lesions.

A 68-year-old woman presented with progressive hemiparesis and dysphagia, initially presumed to have subacute stroke. Serial MRI revealed fluctuating FLAIR hyperintensities and enhancing lesions in the basal ganglia and cortex, ultimately leading to the diagnosis of high-grade primary CNS B-cell lymphoma. The case highlights the importance of integrating clinical evolution with imaging features in atypical neurological presentations. Teaching point: In cases of fluctuating FLAIR hyperintensity and contrast-enhancing brain lesions, primary CNS lymphoma should be considered, even in the absence of typical imaging features.