Abstract: Clinicopathological characteristics of two cases with malignant breast solitary fibrous tumor (SFT) in Peking Union Medical College Hospital were retrospectively analyzed with a review of relevant literature. Both cases presented with giant breast lumps. Surgical treatment was performed with wide local excision of breast tumor without axillary surgery. Immunohistochemical analysis revealed typical SFT histological features with CD34 (+) and S-100(-). The presence of hypercellularity and nuclear atypia supported the diagnosis of malignant SFT. Neither patient received adjuvant systemic treatment. One patient developed local recurrence six months after surgery. Until now, there has been no evidence of distant metastases for both patients. Tumor biopsy is crucial for the diagnosis of malignant breast SFT. Wide local excision and mastectomy remain the mainstay of surgical treatment. Up to now, there is no solid evidence that axillary lymph node dissection and adjuvant chemotherapy/radiotherapy could benefit patients for survival.