[A Case Report of Breast Cancer Followed Up as Intraductal Papilloma].

The patient was a 50-year-old woman. She had been diagnosed with bilateral breast tumors at another hospital 5 years previously and was followed up every 2 months. Ultrasonography showed hypoechoic masses in her breasts. The largest tumor in the right breast was 15mm in diameter and located in region A, while that in the left breast was 8mm in diameter and located in region B. Magnetic resonance imaging(MRI)showed multiple bilateral breast tumors. The largest tumor was 12mm in diameter and was suggestive of breast cancer. Core needle biopsies(CNB)of the largest tumors in both breasts were performed. Intraductal papilloma(IDP)and low-grade intraductal papillary carcinoma were diagnosed in the right and left breasts, respectively, on immunohistochemical staining. We performed left nipple-sparing mastectomy with sentinel lymph node biopsy and right tumor excision for diagnoses of carcinoma of the left breast(cTisN0M0)and IDP of the right breast. The histopathological diagnosis of the left breast tumor was pT1aN0M0, triple negative breast cancer with extensive intraductal components, and that of the right breast tumor was IDP with atypical ductal hyperplasia. Chemotherapy was administered postoperatively. Several studies have reported that peripheral IDP often coexists with or follows the development of carcinoma. Therefore, we should also closely follow-upthe patient's right breast.