Phyllodes tumors are a rare fibroepithelial neoplasm of the breast occurring in approximately 2.1 in every 1 million women with no clear predilection for women of specific races. They are characterized by spindleshaped stromal cells with increased stromal cellularity and increased mitotic activity. The histologic characteristics are similar to that of cellular fibroadenomas making them frequently difficult to differentiate on core biopsy. We present a case of an 82-year-old female with a right breast mass which was initially diagnosed as a fibroadenoma in 2009. She was lost to follow-up and presented in 2021 with complaint of a right breast mass for which diagnostic imaging was performed. A diagnostic mammogram demonstrated a macrolobulated mass measuring 14×12×12 cm which corresponded to the palpable abnormality. The patient subsequently underwent simple mastectomy demonstrating a 14 cm mass with a fibroepithelial structure consistent with a borderline phyllodes tumor. The patient received adjuvant radiotherapy to minimize the likelihood of local recurrence. We concluded that reliable preoperative diagnosis and further studies regarding guidelines for adequate tumor margins and indication for adjuvant radiotherapy are crucial for proper surgical planning and follow-up after excision.