Biopsy-Confirmed Cerebral Amyloid Angiopathy-Related Inflammation With Absence of Cerebral Microbleeds on T2* and Detectable Only by Susceptibility-Weighted Imaging

Cerebral amyloid angiopathy-related inflammation (CAA-ri) is a rare but treatable inflammatory condition in which there is amyloid-beta deposition in cortical and leptomeningeal vessels. Patients with CAA-ri often present with a high number of cerebral microbleeds (CMBs). Susceptibility-weighted imaging (SWI) is more sensitive than T2* for detecting these CMBs. However, SWI is not currently mandatory for the diagnosis of CAA-ri. Here, we present the case of an 82-year-old man with worsening confusion and bilateral visual loss. MRI revealed no CMBs on T2*, but a small number were detected using thin-slice SWI. Histopathology confirmed Aβ-related angiitis with inflammation and amyloid deposits in the vascular media. Steroid treatment improved clinical outcomes, but mild CMBs and increased cortical superficial siderosis were detected on follow-up MRI. As shown in this case, assessment of CAA-ri requires thorough evaluation of CMBs using SWI because T2* alone may be insufficient. If significant CMBs are minimal, leptomeningeal enhancement may indicate the need for biopsy for early diagnosis.