Peritumoral CD117 Immunopositive Mast Cell Density in Prostatic Adenocarcinoma and Its Correlation with the New Gleason Score.

CD117 immunopositive mast cells play an important role in prostate cancer tumorigenesis. Most of the trials on the use of imatinib in prostate cancer have relied on the anti-PDGFR (anti-platelet-derived growth factor receptor) activity of imatinib. The CD117 immunohistochemistry on intratumoral and peritumoral mast cells was performed using the archival blocks of 40 patients with prostatic adenocarcinoma. The mast cells within and at the periphery of the tumor were counted in three areas with the highest mast cell density chosen by scanning the entire specimen section at low magnification, first on hematoxylin and eosin and then on the immunohistochemistry slide. The mean mast cell counts per high power field (× 40) were calculated by taking the mean of 10 high power fields. Then, the mean mast cell count of the case was calculated by taking the mean of all the tissue blocks of the case. The samples were graded histopathologically using the new Gleason scoring system (WHO 2016). The Kruskal-Wallis H test showed that there is a significant association between immunoexpression of CD117 in peritumoral mast cells and different grade groups of the new Gleason scoring system (2016). The p-value for this correlation is 0.02. Peritumoral CD117 immunopositive mast cell density in prostatic adenocarcinoma correlates with the new Gleason score. It may be useful in patient selection for future trials of imatinib for low-grade prostatic adenocarcinoma.