Fig. 2

Example of sampling error and suboptimal frozen section. a No invasive component is found in the frozen section slide, hematoxylin and eosin (H&E), ×100. b A large size of invasion is found in the paraffin-embedded section, H&E, ×100. c Unclear staining of cell structure in frozen section slides, H&E, ×100. d Invasive component was found in paraffin-embedded section, H&E, ×100