I was under the impression that hypochondria is a relatively well understood thing in that we know for certain that it is a mental disorder and not some as of yet understood illness like fibromyalgia or chronic fatigue syndrome.

Are you suggesting that all hypondriacs have some sort of underlying physical ailment and not a mental disorder?

I took their meaning to be that people with undiagnosed health issues which might be hard to diagnose/understand/treat are frequently dismissed as hypochondriacs. The implication being that it’s the assignment of “hypochondriac” by lay people distant from the actual medical situation is the ignorant jump to conclusions, not the people seeking medical attention despite being ignored and dismissed.

The use of the category mental disorder is dated; disorders often have mental components but since the body has no clear separation of the brain and body, it's falling out of use. Also, it wouldn't be the first time a mental disorder turned into a 'regular' disorder, or that is was more of a stigma than an actual diagnosis. Which is why I think find it an interesting option.

As I said, the type of symptoms is broad, so it's unlikely to be one thing. But, I do believe medicine is slowly getting more serious about analyzing also the not clearly apparent symptoms.

I thought hypochondria was mostly manifesting symptoms by the power of suggestion