%0 Journal Article %A John Tawasil %A Edna May L Go %A Julia Y S Tsang %A Yun-Bi Ni %A Chun-Wai Ko %A Gary M Tse %T Associations of epithelial c-kit expression in phyllodes tumours of the breast %D 2015 %R 10.1136/jclinpath-2015-202921 %J Journal of Clinical Pathology %P 808-811 %V 68 %N 10 %X Background Mammary phyllodes tumours (PT) are rare biphasic neoplasms but have important clinical significance. Both epithelial and stromal components participate in PT development. Despite a number of studies on stromal c-kit in PT, little is known about the role of its epithelial expression.Objective To further evaluate the stromal and epithelial expression of c-kit in a cohort of patients with PT.Method and results Expression of c-kit in both epithelial and stromal components was examined and correlated with histological features in PT. Stromal c-kit expression was associated positively with stromal cellularity (median expression=10.0, 30.0 and 50.0 from mild to severe cellularity; p=0.019). Conversely, a significant negative trend between epithelial c-kit expression with stromal pleomorphism (median expression=55.0, 30.0 and 2.5 from mild to severe pleomorphism; p=0.043) and mitosis (median expression=70.0 and 20.0 for low and high mitosis respectively; p=0.003); and a trend of negative correlation with increased PT grade was found. Despite these reverse associations, epithelial and stromal c-kit expressions were positively correlated with each other. Notably, the correlation of stromal c-kit expression with malignant histological features appeared to be stronger in cases with low epithelial c-kit expression but not in those with high epithelial c-kit expression.Conclusions This study demonstrated the association of epithelial c-kit expression with stromal histological features and stromal c-kit. Interestingly, epithelial c-kit expression affected the strength of the correlation of stromal c-kit with these histological features. These findings provide further evidence of the interaction between the epithelial and stromal components in PT. %U https://jcp.bmj.com/content/jclinpath/68/10/808.full.pdf