Fibroadenoma is a commonly found benign tumor of the breast; however carcinoma in a fibroadenoma is rarely encountered. In this paper we described a case of fibroadenoma difficult to differentiate from carcinoma. A 17-year-old woman visited our hospital complaining of a left breast lump. Ultrasonography showed a well-defined and hypoechoic ovoid mass. Excisional biopsy was done and diagnosed as fibroadenoma; however it was difficult to differentiate histologically from carcinoma. The features of fibroadenoma have been greatly changed by the transition of the hormonal environments in Japanese women.
Medical Subject Headings: skin and connective tissue diseasesbody regions