It has often been stated that pathology is primarily a visual discipline. The observation, not always meant as a compliment, has a component of truth, in the sense that a large segment of pathology practice consists in the interpretation of images of one type or another. The magnification range of the images that the pathologist has been asked to evaluate has increased exponentially over the years, from the gross to the microscopic, down to the ultrastructural and cytogenetic; but the basic purpose has remained the same: to extract from the visible structural features all the necessary information in an attempt to ascertain the nature and mechanism of formation of the abnormalities present.