A case report of fibroadenoma of the breast with characteristic cystic change on a cut surface.

Fibroadenoma with remarkable cystic change is very unusual. Opinions differ as to the interpretation of this lesion. Furthermore, there have been few reports focusing on its macroscopic view. We herein report a case of fibroadenoma in a 43-year-old woman. The patient presented herself to a medical doctor's office due to a rapidly growing breast tumor. Based on a core needle biopsy, a benign lesion was suspected, and the tumor was surgically resected. On a macroscopic study, the cut surface of the tumor revealed a remarkably cystic and well-circumscribed lesion with an intracystic polypoid component. Microscopically, a variety of findings of epithelial and stromal proliferation were observed. This is an interesting case not only because a fibroadenoma with prominent cystic change is unusual but also because the breast tumor showed a characteristically cystic appearance on its macroscopic view.