The patient was a 41-year-old, premenopausal woman with a chief complaint of well-circumscribed palpable, right breast mass without nipple discharge. Although she noticed the lump 3 months previously, the size of the tumor (1.1 × 0.9 cm(2)) had been stable. The patient's mother suffered from gastric cancer. Her previous history of the triple different malignancies was as follows: (1) left osteosarcoma [amputation of left lower leg at 15 years old (y/o)]. After the operation, she was treated with various kinds of anticancer drugs including a total of 45 g ifosphamide and 342 g methotrexate; (2) tongue cancer (right radical neck resection; 23 y/o); and (3) thyroid cancer (right lobectomy; 40 y/o). There was no evidence of recurrence of these malignancies at the present consultation. At the time of tongue cancer operation, chromosome abnormality was investigated, but the results were normal. Physical examination showed a well-delimited, elastic-firm, mobile tumor in the central outer right breast. Regional lymph nodes were not palpable. Mammography showed a focal asymmetry in the right upper breast on the mediolateral oblique view. Ultrasonography revealed a hypoechoic mass with irregular margins. Distant metastases could not be detected by whole-body computed tomography scan. The histology of the Mammotome(®) (vacuum-assisted core needle biopsy) specimen revealed that this tumor was low-grade ductal carcinoma in situ (DCIS). She underwent breast-conserving surgery with sentinel lymph node biopsy. On permanent histopathological examination, the diagnosis of the tumor was intracystic papilloma with low-grade DCIS. Surgical margin was negative, and sentinel lymph node metastases could not be observed. Estrogen and progesterone receptor (ER/PR) were strongly positive, but human epidermal growth factor receptor-2 (HER-2) overexpression was not tested because the lesion was DCIS. She has received no adjuvant therapy and is currently disease free 3 months after surgery.