I have a sister-in-law who has a lot of hypochondria symptoms, although I don't believe she's ever been officially diagnosed with it. Every new ache or pain she gets is a cause for panic with her. It can never be anything minor or easily treatable. If she gets a stomach pain, it must be stomach cancer and she's going to be dead in six months. If she develops a cough, she knows for a fact it's an incurable lung disease.
She will schedule very expensive medical procedures, like an open MRI, if she doesn't agree with her doctor's diagnosis. He may think her headaches are triggered by stress or allergies, but she knows for a fact that it's really a brain tumor. She'll demand that he schedule a series of brain scans to rule it out. I think she's a true hypochondriac, because she will not listen to reason. Once she's convinced she's sick, nobody can change her mind.