Cerebral Amyloid Angiopathy Related Inflammation Masquerading as Intracranial Neoplasms: A Biopsy Confirmed Diagnostic Challenge
Maria Muñoz1, Fatima Alao2, Marcos Mota1, Tal Eliav3, Maria V Diaz3, Rebecca Frawley3, Chloe Dominguez1, Nicole Heath3, David Hammer3, Aparna Prabhu3, Ryna Then3
1Instituto Tecnológico de Santo Domingo, 2Sarah Bush Lincoln Hospital Matoon, 3Neurology, Jefferson Einstein Philadelphia Hospital
Objective:

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.


Background:
Cerebral amyloid angiopathy (CAA) is a rare condition most often linked to lobar hemorrhage, but its inflammatory subtype, cerebral amyloid angiopathy–related inflammation (CAA-ri), may present as pure inflammatory CAA or amyloid β (Aβ)–related angiitis. Diagnosis requires clinical, radiological, and sometimes biopsy confirmation. CAA-ri can closely mimic low-grade gliomas radiologically, posing significant diagnostic challenges.
Design/Methods:

Case Report and Literature review.


Results:

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. 


Conclusions:

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.


10.1212/WNL.0000000000212833
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