Immunohistochemically, the breast cancer cells were diffusely positive for AR (Fig. 3) and GCDFP-15 (Fig. 4c), positive for CK7 (Fig. 3), weakly and partially positive for p53 (Fig. 4d), and negative for CK20, CDX2, SATB2 (Fig. 3), ER, PgR, and HER2. The gene discussed is KRT20; the disease is breast carcinoma.