Blood vessel tumour. Light micrograph of a capillary angioma (arteriovenous malformation), in connective tissue. This is a benign (non- cancerous) tumour formed by a clump of dilated capillaries. Angiomas are most often found in the brain or spinal cord. The tumour may burst, causing haemorrhage, or compress areas of the brain or spinal cord, causing complications such as epilepsy. Due to this the tumour may be surgically removed or destroyed by having its blood supply cut off.