A complex case of moyamoya disease mimicking vasculitis: diagnostic challenges and systemic complications in a young adult.

Moyamoya disease (MMD) is a rare, chronic cerebrovascular disorder that can mimic vasculitis, making diagnosis challenging. We present a 35-year-old Filipino woman with occipital headache, left-sided facial weakness, and transient left arm numbness. Initial CT was unremarkable, but MRI showed multifocal ischemic infarcts; MRA later revealed bilateral MCA and ACA occlusions with collateral vessels, confirming MMD. Laboratory testing was negative for inflammatory markers, and PET-CT excluded vasculitis. The patient received antiplatelet therapy and blood pressure control, but her course was complicated by myocardial infarction and acute kidney injury, precluding surgical intervention. This case underscores the importance of early advanced imaging and comprehensive evaluation in young patients with recurrent strokes to distinguish MMD from vasculitis, enabling timely and appropriate management.