Phyllodes tumor is a benign breast cancer with a malignant potential. It is very rare in Saudi Arabia and also rare around the world. Malignant phyllodes tumors originate from the connective tissue of the breast, so they are histologically sarcomas. We report the largest phyllodes tumor ever seen in Saudi Arabia, a 41-year-old female who presented with a huge breast mass occupying the whole breast with areas of ulceration. Her history had started 14 months previously with a slowly growing left breast swelling, ultimately the lump ulcerated and became necrotic. Mastectomy with partial resection of the pectoral muscles was done. The tumor specimen measured exactly 30×20×13 cm in size, and weight of 5.4 kg, and with the closest margin of resection 0.5 cm away from the tumor the histopathology report came back as malignant phyllodes tumor. The patient was sent for radiotherapy and chemotherapy. We concluded that accurate preoperative pathological diagnosis is very important for management of phyllodes tumor, and allows correct surgical planning and avoidance of reoperation.
Keywords: Breast; Malignant; Phyllodes tumor; Prognosis.