Histopathology from biopsy and bilateral mastectomy demonstrated infiltration of large Paget’s cells in the epidermis of the areola with underlying lesions of invasive ductal carcinoma, diagnosed solid type with high nuclear grade and negative expression of estrogen receptor and progesterone receptor, with positive expression of human epidermal growth receptor-2(HER2) and Ki-67 (45%). The gene discussed is ERBB2; the disease is invasive ductal breast carcinoma.