Two ideas:
Firstly to stress the need to choose the right doctor;
Secondly: to realise that a second oppinion is necessary when the diagnostic is extreme.

Read the following short story, where a Man awaits death when his problem is that his collar is too small

Simple diagnosis

A young man told his doctor, «I get headaches, my ears burn, I see spots before my eyes, and I can’t breathe.»
The doctor examined him thoroughly and told him, «Your brain isn’t getting enough blood and oxygen. At this rate, you’re going to lose consciousness and go into a coma. No surgery or medicine can help you. I suggest that you quit your job and spend your few remaining days enjoying yourself.»
So the poor fellow followed his doctor’s advice. He quit his job, withdrew his savings from the bank, and bought a ticket for a flight around the world. The day before he left, he went to a men’s clothing store to buy some new shirts. The salesman asked him his neck size.
«Fifteen,» he said. Just to make sure, the salesman slipped a tape measure around his
neck. «It looks like you actually wear a 15 and 112 collar,» he said. «No,» insisted the doomed man. «I wear a 15 collar. I always have.» «Well, okay,» the salesman shrugged. «I’ll sell you shim with size 15 collars, but do you know what will happen? They will cut off your circulation to the brain. You’ll get headaches and your ears will burn. You’ll see spots before your eyes, and you won’t be able to catch your breath…»
The customer stood speechless. A shirt salesman had solved his medical problem, which a professional doctor had given up.
Some problems have simple solutions.