Frequency of deep-seated cerebral microbleeds in patients with lobar hemorrhages and histopathological evidence for cerebral amyloid angiopathy

BACKGROUND: Cerebral amyloid angiopathy (CAA) is a common disease and the most common cause of lobar hemorrhages in the elderly. Usually, deep-seated microhemorrhages preclude the diagnosis of CAA. In this study, we sought to estimate the frequency of deep-seated microbleeds on MRI in patients with lobar hemorrhages and histopathological evidence for cerebral amyloid angiopathy. In addition, we describe a cohort of patients with cortical and deep-seated microbleeds on MRI and a histopathological specimen available from lobar hematoma evacuation. METHODS: Retrospective database search for histopathological specimens from lobar hematoma evacuation and review of imaging findings (CT and MRI) and patient charts was performed. RESULTS: Between 1 January 2012 and 31 December 2020, 88 specimens from 88 patients were available. A total of 56 specimens were excluded (no brain tissue in the specimen n = 4, other diagnosis n = 8, no MRI n = 43, and no BOLD-based sequence n = 1). Of the remaining 32 patients, 25 patients (78%) did not harbor deep-seated lesions on MRI, of which 17 patients had histopathological features of CAA. A total of seven patients harbored deep-seated CMB. Of these seven patients, three (3/20, 15%) had histopathological features of CAA. CONCLUSION: Approximately 15% of patients with histopathologically diagnosed CAA harbor deep-seated microbleeds. This finding may add to the discussion on how to identify patients with CAA and deep-seated CMB.