[Breast cystosarcoma phyllodes. A clinicopathologic study of twenty-seven cases].

Twenty-seven cases of cystosarcoma phyllodes (CSP) diagnosed at the Veterans General Hospital, Taipei, were reviewed. Of the twenty-seven cases, seventy per cent were benign, thirty per cent were malignant. One of the malignant cases was transformed from benign one. Of the benign CSPs, one had multifocal lesions and eight were associated with other breast lumps, including fibroadenoma and fibrocystic disease. The mean age of patients with benign CSP was 33 years old, and with malignant CSP, 52 years old. The most frequent location was in upper outer quadrant. We found no positive correlation between tumor size, clinical symptoms, tumor epithelial carcinoembryonic antigen, hypervascularity, mixed mesenchymal components, and benign or malignant CSP. Estrogen and/or progesterone receptors were positive in five benign CSPs detected, but malignant CSP was negative. Variable degrees of epithelial hyperplasia, squamous metaplasia, and apocrine metaplasia, were found in both benign and malignant CSPs. Part of the epithelial component in CSP may be derived from normal breast lobule and duct being trapped into the tumor during tumor infiltration. The mesenchymal differentiation in malignant CSPs include fibrosarcoma, malignant fibrous histiocytoma, liposarcoma, and collision of chondrosarcoma and malignant fibrous histiocytoma. One of the malignant CSPs was found within an old, calcified fibroadenoma. When benign CSP was excised under impression of fibroadenoma, the recurrent rate was 50%. In view of this, we recommend a wide excision for a benign CSP. No axillary lymph node metastasis was detected in malignant CSP, so radical mastectomy was not indicated.