Dear P-girl....your dad's lesion began much as mine did, exc. when it presented itself as a lesion with, as you call it, "a red, blistery rash," my dentist did not recognize it. I realize that this is one, individual practitioner who was not properly educated and motivated to diagnose oral cancer, and that most are more alert than that. This was a young-ish dentist....not brand new, not elderly.....has young children, 6-10 yrs. old.....recently trained.....There is simply no excuse. It's a good thing I am not the suing type, because this is a clear case of "failure to diagnose," when a practioner does not perform within the reasonable expectation of his specialty. He allowed my clearly visible lesion to remain for over 8 months, not recognizing it even when it was classic, as you father's was. I had to insist on more attention, and then he reluctantly sent me to the periodontist....still not the right place to be......and that dr. sent me immediately to the oral surgeon for a biopsy.