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Keywords:

  • PHH3;
  • gastrointestinal stromal tumors;
  • prognosis

ABSTRACT

Background and aim

The biologic behavior of gastrointestinal stromal tumors (GIST) is a topic of continuing controversy. The assessment of accurate mitotic figures is known to be one of the major indicators for patients with GIST. However, it is not always easy to search for mitotic figures (MFs) and count them accurately on hematoxylin and eosin stained (H&E) slides.

Methods

In this study, phopho-histone H3 (PHH3), which is a recently described specific mitosis marker, was immunohistochemically examined and compared to the mitotic count on H&E sections (H&E-MI) and Ki-67 expression (Ki-67 PI). A hundred cases of histologically confirmed GISTs were reviewed based on counting MF on H&E slides. PHH3 positive MFs (PHH3-MI) were counted in the same way, and the Ki-67 PI was calculated for each case.

Results

A strong correlation was found between PHH3-MI and H&E-MI. Recurrence-free survival was correlated with risk category by National Institutes of Health (NIH) consensus criteria (P = 0.017), mucosal invasion (P = 0.005), H&E-MI (P = 0.002), Ki-67 PI (P = 0.005), and PHH3-MI (P = 0.000). None of these factors was an independent prognostic factor.

Conclusions

Among GISTs, PHH3 staining was primarily found to support grading by facilitating mitotic counting, and it might have a prognostic value in GISTs.