Abstract
A 74-year-old woman was seen at our hospital because of a tumor in her right breast. A 3 cm elastic hard and smooth mass was palpated in the C area of her breast. Fibroadenoma was diagnosed by fine needle aspiration cytology, and we decided to follow her in the outpatient department. However, at the next visit to our hospital 18 months later, the right breast tumor had grown into a 7×4 cm mass. Probe lumpectomy was performed under general anesthesia. Pathological examination showed invasive ductal carcinoma arising in a borderline malignant phyllodes tumor. The adjuvant treatment was hormonal therapy (letrozole) for 5 years, and no apparent recurrence or metastasis was seen for 6 years after surgery.
It is very rare for invasive ductal carcinoma to arise in a phyllodes tumor, and only 17 cases including our present patient have been reported to date in Japan.
