I don't mind being the bearer of bad news. I don't like it, but hey, it's part of the job.
But it really chaps me when a patient shows up "because Dr. Doofus said you'd tell me what the MRI showed". Most of the time Dr. Doofus hasn't even had the common courtesy to send me a copy of the damn report.
And in almost every case the studies are NORMAL. That's all. Or have some minor, benign variant like a harmless cyst. And so, because of human nature, the patients assume the worst. After all, Dr. Doofus is stonewalling them, and sends them to a specialist, so it must be time to draw up a bucket list.
Or they have a minor, benign, variant, and Dr. Doofus tells them it's either something horrible (because he has no idea what it is) or that it's sole the cause of ALL their symptoms, and Dr. Grumpy will know how to fix it. When in reality it's as relevant to their headaches (or whatever) as a hangnail would be.
I don't understand a lot of stuff in my own field, let alone outside of it. I don't expect other doctors to be any different. But if you don't know what it is or means, just be honest and say "I don't know!"
And DON'T tell them that they have to see me to get the results, then refuse to give them. They spend sleepless nights worrying about them. And when they invariably find out the test was normal, they get really pissed off at you. I've seen patients change doctors over that. And I don't blame them.