[A case regarded as an occult breast cancer treated without mastectomy].

A 51-year-old woman was admitted to our hospital with a chief complaint of left axillary tumors. No such tumors were detected in bilateral breasts by ultrasonic tomography, mammography, computed tomography, and magnetic resonance imaging. The core needle biopsy from the left axillary lymph node was examined, and the specimen revealed an occult breast cancer, because the microscopic findings resembled the breast cancer organization and immunochemistry revealed positivity of the estrogen receptor. The radical left axillary dissection was operated. Tamoxifen and FEC 100 6 cycles were selected as adjuvant treatment. At one year after operation, she has no recurrence. Carcinoma cells had portedly been recognized in the mammary gland with 82.7% of the cases who had undergone mastectomy for occult breast cancer. However, in many cases, the patient's consent for mastectomy was not obtained like as in this case, and the choice of treatment is often difficult. We considered that the case's accumulation was necessary to verify the possibility of the mastectomy omission to an occult breast cancer, presented the case report.