Identification of Phosphohistone H3 Cutoff Values Corresponding to Original WHO Grades but Distinguishable in Well-Differentiated Gastrointestinal Neuroendocrine Tumors

Figure 1

Mitotic figures (Arrows) in a rectal neuroendocrine tumor (a, d, g) and a colonic neuroendocrine tumor (b, e, h) stained with H&E (a)–(c), Ki-67 (d)–(f), and PHH3 (g)–(i). (d)-(e) Ki-67 is more frequently positive in tumor cells, whereas (g)-(h) PHH3 highlights mitosis-specific nuclei, aiding in recognition. (c) Apoptotic bodies (Dotted arrows) mimicking mitosis are found in gastric neuroendocrine tumors. (f) Faint Ki-67 staining in an apoptotic nucleus, apparently false-positive. (i) Lack of PHH3 staining of apoptotic cells.

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