Recurrent giant phyllodes tumor of the breast: a case report.

Background: Phyllodes tumors (PTs) account for 0.3-1.0% of all breast tumors and often occur in women aged 35 to 55. They are similar to giant fibroadenomas. PTs are famous for local recurrence. No more than 10% of PTs grow larger than 10 cm. The National Comprehensive Cancer Network (NCCN) guidelines recommend extensive resection with a margin of ≥1 cm for PTs, which is much larger than that required for breast cancer. Positive resection margin is associated with recurrence. However, little is known about whether all subtypes really require radical tumor negative resection margins. Case Description: We report on a 49-year-old woman with a giant borderline PT in her left breast. The tumor was greater than 10.5 cm × 7.0 cm. She had a bilateral benign PT excision in January 2014 and a left benign PT excision in December 2018. A chest computerized tomography (CT) scan and abdomen ultrasound did not reveal distant metastasis. Therefore, left breast mastectomy was performed. Wound healing was satisfactory. Pathological and immunohistochemistry findings showed a borderline PT. Conclusions: As the rare tumor of the breast, PTs pose a great challenge for surgeons. The initial evaluation of PTs relies on a triple evaluation of clinical, radiological, and histological examination. Local recurrence of PTs is more common than distant metastasis. The histology of recurrent tumors is usually identical to that of the primary tumor, or has a tendency to malignancy. Although most surgeons are uncomfortable with PTs with a positive margin, it is reasonable to adopt a "watchful waiting" strategy for benign PTs. The current recommendation that PTs should be extensively resected regardless of tumor size might be revised.