All considered, I feel being diplomatic, is good training. When some one says "I think this is a benign ulcer", instead of retorting "No I think it is malignant" - it does not take much effort to say " It could be.. it is of course possible, but I think it is almost certainly malignant'. You friend will get the idea and ask for a biopsy. He will not send a sleepless night over how he had made a fool of himself. One needs to be particularly careful especially when discussing "mistakes" committed by fellow physicians in front of patients. When it is a honest error, or mistake and not a case of negligence, there is no need to rub it in; gently explain to the patients how such things can and do occur - after all no one is God.. Remember, one day the shoes may be on the other foot,