Don't be crass. You obviously don't understand the level of investigation we're talking here. It is just not possible in a patient like this to examine every single piece of sampled tissue 100%, not unless you want to spend a day on every patient and reduce the wellbeing of the population, to eliminate an already very unlikely diagnosis. Do you know how small cells are? The sample's we're talking are many macroscopic lumps if tissue, cut in cross sections into many more slides, the granulomas we're talking about are groups of 30 or so cells. This could have been the only one. How long do you expect the doctors to look for it? It would be stupid to expect to look all over every sample.
And I find your example a bit hard to swallow - sorry the nurse shouldn't be TOLD the drugs, she should read them from the drug chart, to eliminate human error. Also, you imply that if he had used the right name then the nurse would have spotted the drug interaction? No, sorry, no nurse in the world will argue with a specialist about drug interactions - doctors and nurses are incredibly important in patient care, and they fulfil completely different roles - the nurses role is NOT to spot drug interactions, they are not taught about them, and the doctor knows best about these things. Similarly, I wouldn't expect the doctor to tell the nurse how to do aspects of her job.