Colocalization of Tau but Not β-Amyloid with Cortical Superficial Siderosis in a Case with Probable CAA

Cortical superficial siderosis (cSS) is a common feature in patients with cerebral amyloid angiopathy (CAA). The correlation between β-amyloid and/or tau pathology and the occurrence of cSS is unclear. We report on an 80-year-old male patient who was diagnosed with probable CAA according to modified Boston criteria and underwent longitudinal magnetic resonance imaging, amyloid positron emission tomography (PET), and additional tau PET imaging. Amyloid deposition presented predominantly in the contralateral hemisphere not affected by cSS. In contrast, tau deposition was predominantly overlapping with brain regions affected by cSS. Amyloid deposition was not different in the vicinity of cSS whereas tau depositions were elevated in the vicinity of CSS-affected regions compared to non-cSS-affected brain regions. This case of probable CAA suggests that cSS may be associated with a locally elevated tau pathology but not with increased fibrillary amyloid deposition.