MICROSCOPIC DESCRIPTION: The section shows fragments of blood clot consisting predominantly of red blood cells with a small amount of fibrin. At one edge there are several small calibre blood vessels. These show thickening and hyalinisation of their walls. Immunohistochemistry shows strong staining for A-beta protein within vessel walls. The features are of amyloid angiopathy. No evidence of tumour is seen.
FINAL DIAGNOSIS: A-beta amyloid angiopathy with haemorrhage.