Placebos are an extremely powerful treatment for many medical conditions. Although you have asked for case reports, a paper published in 2015 by Espay and colleagues in Neurology is one of my favorite papers of all time.
In it, the authors randomized participants with Parkinson disease (a neurologic disease characterized by tremor, slow movement and rigidity) to receive a placebo which they referred to as a "novel injectable dopamine agonist". One of the first line treatments for Parkinson disease is dopamine. Half were randomized to be told the drug was "cheap" and the other half were told it was "expensive". They assessed motor function and did some brain imaging blinded to the randomization status. Then they crossed the participants over to the other group (that is the cost branch they had not yet received) and repeated the process.
As can be seen in Figure 2, the "expensive" placebo, but not the "cheap" placebo significantly improved the motor function of the participants. There were also fMRI changes, but the results are more complicated.
Still, salt water that the participants thought was expensive actually made them tremor less and move more easily.
Think about that the next time you take some acetaminophen.
You don't state in your question the time scale you are interested in, but this is a report of 12 people with Parkinson disease who saw concrete benefits from placebo for a day.
