How do histopathologists look at slides?

When a histopathologist looks down a light microscopy we have very little idea of what different patterns of observing might happen. As trainees we probably did a lot of work on double-headed microscopes with experienced consultants so we would get some idea of the methods they used, I was always very impressed by how very good diagnostic pathologists could zoom in on a diagnostic Reed-Sternberg cell or a tongue of microinvasion after a very quick scan over the slide at low power. With the introduction of digital images in diagnostic histopathology it is possible to record the actions of pathologists as they observe slides and to look for any recurrent patterns in those actions. Molin et al. in this month’s Histopathology look at the patterns of observation of five pathologists looking at four cases (some of which had multiple slides with immunohistochemistry). They found, and elegantly illustrate, a number of different patterns including directed panning, cover panning, sporadic panning and dip zooming – giving us a whole new vocabulary for the way we look at slides. They show that pathologists do use methods of looking at digital images that cannot be used down the light microscopy and so are showing adaptation to the new technology. There is probably scope for a lot more related studies as histopathology moves towards full digital reporting.