[Amyloid β-related angiitis (ABRA) with dural contrast enhancement]

An 82-year-old woman presented with a rapidly progressive decline in cognitive function, which had previously been worsening over several months. Brain MRI revealed a lesion predominantly involving the leptomeninges of the right parietal lobe. Based on the presence of leptomeningeal-predominant lesions, cerebral microbleeds, and superficial siderosis, amyloid β-related angiitis (ABRA) was suspected. However, due to atypical findings such as dural enhancement, we performed a brain biopsy, leading to a definitive diagnosis of ABRA. Steroid therapy resulted in improvements in both clinical symptoms and imaging findings. Imaging findings in this case suggest that inflammation originating in the leptomeninges extended bidirectionally into both the brain parenchyma and the dura mater. This progression pattern is of particular interest for understanding the pathophysiology of ABRA and may offer a future possibility of avoiding brain biopsy by identifying characteristic imaging features.