The traditional “manual macrodissection” method for dissecting formalin-fixed paraffin-embedded (FFPE) tumor slides is no simple task: Pathologists first determine where in an H&E-stained slide tumor cells abound, trace that area to demarcate it, and direct the lab to use that annotated slide as a reference for dissecting the area of interest (AOI) for serial slides. Subsequently, lab techs are expected to interpret and replicate the AOI specified by the pathologist faithfully: They place the reference slide underneath the serial section slide from the same paraffin block to align the two, then trace the AOI onto the serial slide with a marker pen, and finally use a scalpel to carefully scrape off the tissues within the marked AOI for downstream molecular analysis.1
Such a manual method for tumor dissection, though common, has several drawbacks. For starters, an innocuous factor such as the thickness of the marker pen used to trace can change the precision by a millimeter! The manual method, on top of being physically demanding, can also introduce errors from extrapolation during overlapping of slides, and can suffer from misinterpretation of hand-written notes and poor documentation practices.2