What are the five most costly diseases and their prevalence in the U.S.?

By “costly” I mean the expense of treatment, in dollars, not in terms of death rate, physical impairment, etc., and I mean on a per-patient basis, not an aggregated sum.

That is, if I have disease A, it is going to cost (me, insurance company, government, someone) $X to treat me, and if I have disease B it is going to cost $Y. And X is greater than Y. Per person. So in terms of costliness, it doesn’t matter whether everyone has the disease or only one person. I am speaking of individual cost.

And then, of those 5 most costly diseases, how do those rank in terms of number of cases in the U.S.? Are the most costly diseases the rarest ones? the most common? somewhere in between?

I tried to look this up through Google and found answers for “most costly” expressed in millions of dollars total, meaning what all the cases taken together cost “us,” and not case by case. This means that the total number of cases is a factor in the ranking; if enough people have the cheapest disease, it will be at the top. I’m trying to separate cost from number of cases and see which are the most expensive diseases a person can have.