Just a couple of thoughts. I agree, I think that's the most natural way to read it, but physicians often speak without precision when it comes to language itself, so I can also see them perhaps meaning it neutrally so both false positives and false negatives: "incorrect diagnosis" period. But perhaps they're speaking precisely here and they just mean what you say. I'm inclined to read it like you, at least naturally, but I can't be sure. Regardless, it's worth asking about this and noting that one has a preference for one over the other, given this information. Also, since they look for morphology on these biopsies too, it's worth noting that improper handling may degrade both the nerve fiber density and the morphology of the sample, I don't know.

Thanks for posting this. Before my biopsy I had read that often the results can be influenced by poor handling, but I didn't know the solution mattered in this way.