The analysis of DNA, RNA and proteins obtained from diagnostic specimens, is currently revolutionizing the practice of surgical pathology and heralds a new era of diagnostic and prognostic tests that will greatly influence our day to day clinical decision making. The diagnosis of cancer and many other diseases is fundamentally based on the microscopic study of cells and tissues. Nevertheless, the era of the pathologist relying entirely on the examination of tissue sections stained by histochemical methods is gradually being replaced by a time when advanced immunologic and molecular techniques...