Fig. 1: Schematic representation of the cases included and analyses conducted in this study.

Depiction of the cases evaluated in this study, encompassing breast papillary lesions including tall cell carcinomas with reverse polarity (n = 14), intraductal papillomas (n = 13), solid papillary carcinomas (n = 16), and encapsulated papillary carcinomas (n = 5) subjected to Sanger sequencing analysis of the IDH2 R172 hotspot locus and of exons 9 and 20 of PIK3CA, and to the immunohistochemical analysis for IDH2 R172 (clone 11C8B1). Triple-negative breast cancers (n = 226) were subjected to immunohistochemical analysis of IDH2 R172 expression using tumor microarrays.