To describe a rare case of cerebral amyloid angiopathy–related inflammation (CAA-ri) mimicking a low-grade brain tumor on brain magnetic resonance (MRI), highlighting the diagnostic challenges and the importance of advanced neuroimaging and clinical suspicion in differentiating CAA-ri from neoplastic processes.

Case Report and Literature review.

We report the case of a 74-year-old woman with congestive heart failure, monoclonal gammopathy of undetermined significance, Raynaud's and migraine presenting with lethargy in the setting of mild hyponatremia. Initial 1.5T MRI revealed a non-enhancing right parieto-temporo-occipital area suspicious of low-grade glioma. Serial MRIs, including 7T MRI, demonstrated progressive FLAIR hyperintensities with multiple new foci of susceptibility on GRE sequences, raising concern for CAA-ri. MR spectroscopy showed no significant hyperperfusion or choline elevation to suggest a high-grade glioma. The clinical course was significant for new onset seizures, fatigue, and mild cognitive impairment.  The patient underwent a right temporal brain biopsy which showed mild increased cellularity and no evidence of neoplasm. Beta-amyloid–positive plaques and vascular amyloid deposits confirmed CAA. High-dose steroid therapy was declined by the patient; nonetheless, follow-up MRIs demonstrated improvement of signal abnormality and presence of microbleeds, consistent with CAA-ri. 

This case highlights the potential of CAA-ri to closely mimic infiltrating gliomas radiologically. Advanced high-resolution neuroimaging revealed characteristic microhemorrhages not visible on conventional 1.5T MRI. Awareness of this overlap is critical to avoid misdiagnosis and unnecessary interventions, underscoring the value of multidisciplinary evaluation and clinical suspicion in atypical cases.