ESR1 and breast carcinoma: FOXA1 regulates the transcriptional activity of ER and may function cooperatively in the tumorigenesis of breast cancer.<h4>Methods</h4>We performed immunohistochemical staining for FOXA1 and ER using tissue samples from 16 patients with EMPD.<h4>Results</h4>The nuclei of Paget cells isolated from each of the 16 patients with EMPD (100%) were strongly FOXA1-positive, and the FOXA1 staining intensity was similar across all samples.