ectasia

mediastinm: Mild ectasia aorta probably approaches 3.7 cm.  No mediastinal or hilar lymphadenophy. No pericardial abnormality.
What does this mean?

[bypeep]

Your doctor would be able to give you definitive answers, however a quick Google search on 'ectasia aorta' brings up results referring to a mild dilation of the aorta - which is the large artery leading out of the top of your heart and eventually down into your abdomen. Since it says mediastinm, this means this finding is in your thoracic cavity (chest area) as opposed to your abdominal.  It could be any number of things really.

The other results are "normal" - you don't have enlarged lymph nodes (lymphadenopathy) in the area they observed and they also found no pericardial abnormalities (area around your heart).  

I'm assuming this was from a CT scan or MRI?  

When you have a follow-up about this test with your doctor, jot down some notes as to your concerns and have them answer each one for you.  Bring the report with you, I always find that's helpful when I forget to bring things up.