[Diagnosis of a Non-Invasive Ductal Carcinoma, Assisted by Long-Term Follow-Up of Spontaneous Nipple Discharge - A Case Report].

We report a case of a non-invasive ductal carcinoma revealed on long-term follow-up of spontaneous nipple discharge. The patient, a 36-year-old woman, had noticed spontaneous nipple discharge from both breasts over a 3-year period. Mammography and ultrasonography did not reveal any lesions in the breasts. The nipple discharge from her left breast stopped 36 months after initial clinical assessment. However, the nipple discharges from her right breast transformed into a bloody discharge from a single duct. Ultrasonography showed a tumor, 6mm in diameter, in the upper-outer quadrant of her right breast. A core needle biopsy for breast tumor led to a pathological diagnosis of non-invasive ductal carcinoma. We conducted a whole-body clinical examination but no metastatic lesions were detected. Subsequently, we performed breastconserving surgery and sentinel lymph node biopsy. The pathological diagnosis was non-invasive ductal carcinoma in situ. The tumor was positive for estrogen and progesterone receptors, but negative for HER2/neu. The Ki-67 labeling index was 5%. The surgical margin was negative. We diagnosed the tumor as TisN0M0=Stage 0. Endocrine therapy comprising tamoxifen (20mg/day)was initiated. Four years after surgery, she was well without any metastases.