A case of an elderly individual with breast cancer diagnosed as Paget's disease after mastectomy

We report here a case of a 78-year-old woman, who underwent mastectomy for breast cancer. Mammography showed a mass in the right MO area with an unclear boundary. Ultrasound examination revealed an irregular mass of 40×29×19 mm in the right C region. Dynamic contrast-enhanced MRI showed a 34 mm tumor with contrast effect in the C area of the right breast. We performed a core needle biopsy on the mass, and the histopathological diagnosis was apocrine carcinoma (ER-, PgR-, HER2 3+, and Ki-67 30%) of clinical T2N0M0, stage HA. Right mastectomy and sentinel lymph node biopsy were performed. In the postoperative pathological examination, the main lesion was apocrine carcinoma (ER-, PgR-, HER2 3+, Ki-67 20%) and Paget's disease (ER-, PgR-, HER2 3+, Ki-67 30%). After surgery, the patient was given trastuzumab therapy.