Brain Tumor/ Not a Brain Tumor

I had a close family member who recently passed away.  She was initially diagnosed with a malignant brain tumor and was awaiting results of what kind of cancer it was to determine treatment approach.  She ended up dying - they say her heart gave out but she never had indications to my knowledge of heart trouble.  This week the doctor called and said that her she didn't have cancer and that it wasn't a tumor.  Rather I understood that it had to do with something about the nerves and veins malforming or intertwining.  I know this isn't much information but could you share some possibilities of what this might have been so that we could read about it?

Thank you

[CCF-Neuro-M.D.-JT]

I'm sorry to hear about your family member's recent passing. What they may be talking about is an AVM or arterio-venous malformation. This is an abnormal collection of tangled blood vessels that can be located in or on the surface of the brain. Depending on certain anatomic features, its risk of bleeding is usually less than 5%. It can sometimes look like a mass on a scan, but neurologists and neuroradiologists should be able to tell the difference. Treatment consists of surgery or endovascular approaches. Hope that helps