MACROSCOPIC DESCRIPTION: A rectangular fragment of brain tissue with attached vessels 10 x 6 x 3mm.
MICROSCOPIC DESCRIPTION: The section shows cerebellar parenchyma in which there is a nidus of vascular channels which extend into the subarachnoid space. These are predominantly venous in type but show an arrangement of elastic fibres within their walls consistent with arterialisation. Several small arterial vessels are also seen. The features are consistent with arteriovenous malformation. No evidence of tumour is seen.
DIAGNOSIS: Features consistent with arteriovenous malformation.