microhemorrhage
Small focal bleeding in brain tissue, typically less than 2mm in diameter. Often associated with cerebral amyloid angiopathy or hypertensive changes.
Full Definition
Microhemorrhages are minute focal areas of bleeding within the brain parenchyma, usually measuring less than 2 millimeters in diameter. They appear as small, dark red or brown spots grossly and show collections of red blood cells and hemosiderin-laden macrophages microscopically. These lesions are commonly associated with cerebral amyloid angiopathy, hypertensive arteriopathy, or trauma. Their distribution pattern can provide important clues about the underlying pathophysiology: cortical and subcortical microhemorrhages suggest amyloid angiopathy, while deep gray matter microhemorrhages indicate hypertensive microangiopathy. Detection requires careful gross examination and may be enhanced by iron stains.
Usage
Usage note: Document size, location, and distribution pattern for diagnostic significance.
In Context
- "Multiple cortical microhemorrhages were identified, supporting a diagnosis of cerebral amyloid angiopathy." — Neuropathology report
- "The distribution of microhemorrhages in the basal ganglia suggested hypertensive microangiopathy." — Forensic autopsy