Background: To distinguish between a benign and malignant phyllodes tumor before surgery is difficult. Wide excision or mastectomy with adequate free margins is necessary in the case of a malignant phyllodes tumor. However, repairing the skin defect after removal of a giant malignant phyllodes tumor is a great challenge for the breast surgeon.
Case report: We report the case of a 45-year-old Taiwanese woman with a giant malignant phyllodes tumor measuring 30 x 25 x 22 cm. Prior to surgery, we carefully designed a flap to cover the skin defect, following standard mastectomy with at least 2 cm free margins. Postoperatively, the patient recovered well without any wound infection or flap necrosis. During follow-up at our outpatient department, there was no evidence of local relapse or distant metastasis.
Conclusion: Giant malignant phyllodes tumors can be treated by total mastectomy with adequate free margins, using a flap technique to cover the skin defect.