Fig. 1: Examples of cases with perfect and 2-step discordance.

A Whole-slide scanned image of case with perfect overall grading concordance shows a homogenous tumor lacking any tubule formation. B On higher magnification, the carcinoma shows pronounced nuclear pleomorphism. The presence of apoptotic debris (circles) did not affect enumeration of the conspicuous mitoses (arrows). C Whole-slide scanned image of case with two-step overall grading discordance shows a tumor with variable tubule formation. D While nuclear pleomorphism was predominately intermediate, occasional higher grade cells were present (not shown). In this case, differentiating mitoses (arrows) from apoptotic debris (circles) likely contributed to a two-step discordance in mitotic rates amongst the six pathologists. E Whole-slide scanned image of case with two-step overall grading discordance amongst pathologists shows a tumor with heterogeneous tubule formation. F Nuclear pleomorphism scoring was split evenly amongst pathologists between grades 2 and 3. Both heterogeneity in mitotic activity and difficulties in differentiating mitoses (arrows) from apoptotic debris (circles) likely contributed to a two-step discordance in mitotic rates amongst the six pathologists.