This should be made known - the fact that a blank section was found. Doing this, more people are aware of the fact that there seems to be something missing, something which could cause an issue later on. Another thing that can be done is going back to the source and finding out why there is a blank section in the medical report in the first place.
If it's getting annoying or is in any way inappropriate, cut it off now. However, if he is not completely mean, wait. You don't want to be unkind. Funniest thing to do would be to say "You're like a brother to me," But that would be mean and awkward, so it's best to just wait it out...
Maybe in your job you have to sit for awhile. Or driving something like that.
hope I helped.
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