The utility of phosphohistone H3 in early prediction of benign and borderline phyllodes tumor recurrence

Abstract

Objective Phyllodes tumors (PTs) have an increased potential for local recurrence even if histologically benign, and some may follow a malignant course. PTs are often treated with simple surgical excision without margins (enucleation), rendering them more liable for local recurrence. Therefore, the analysis of tumor recurrence according to histologic grade would be especially useful in clinical practice. Grading of PTs is based on several histological parameters, but mitotic count (MC) is the only one that can be quantified, unlike most other histological criteria. Manual counting of mitotic figures is time consuming, and there are some difficulties in identifying mitotic figures. The aim of this study was to assess the reliability of phosphohistone H3 (PhH3) in detecting and counting mitotic figures instead of manual MC in benign and borderline PTs and correlation with manual MC and Ki67 in prediction of tumor recurrence.Materials and methods In all, 92 cases of PTs were selected from Tanta Pathology Department Database Section, Tanta University, Egypt, within the period from March 2014 to March 2019 after regrading the tumors based on counting mitotic figures manually at the highest stromal cellular area at 10 adjacent high-power fields. Benign and borderline PTs with free or close margins (<1 cm) were included, whereas malignant cases and cases with infiltrative margins were excluded from this study. Afterward, the selected cases were immunostained for both PhH3 and Ki67 for further correlation with manual MC.Results Of the studied 92 cases, 17 (18.5%) cases had local recurrence after resection of the primary tumor. On correlation of clinicopathological and histological features, Ki67 labeling index (LI), PhH3 MC, and manual MC with recurrence, it was found that there is a significant positive correlation of tumor size, tumor margin, and PhH3 MC with recurrence (P=0.019, 0.000, and 0.000, respectively). Manual MC and Ki67 LI showed a positive correlation with recurrence in studied cases but was statistically insignificant. Moreover, a significant positive correlation was found between both manual MC and Ki67 LI and PhH3 MC (r=0.884, P<0.001, and r=0.785, P<0.001, respectively).Conclusion PhH3 MC was superior to manual counting mitotic figures in recurrence risk stratification of PTs. Tumor histologic grading using PhH3 is as crucial as resection margin status in predicting tumor recurrence in benign and borderline PTs.