Sarcomatoid tumours of the breast in Denmark from 1977 to 1987. A clinicopathological and immunohistochemical study of 100 cases.

One hundred sarcomatoid breast tumours, which had been diagnosed and registered in Denmark from January 1977 to January 1987, were subclassified using a combination of conventional morphological evaluation and immunohistochemistry, and the diagnosis was in each case related to clinical follow-up of 5-14 years or until death of the patient. Conventional histological examination resulted in 36 benign, 19 borderline and 18 malignant phyllodes tumours, 1 angiosarcoma and 26 non-specified sarcomatous tumours, 6 with small carcinoma-like foci. Immunohistochemical staining revealed that 23 of the non-phylloid sarcomatous tumours showed a tumour cell reaction for epithelial markers, predominantly cytokeratin and, therefore, the tumours were interpreted as metaplastic carcinomas. Clinical follow-up showed for phyllodes tumours and for the three cytokeratin-negative sarcomatous tumours local recurrence rates of 21 and 33%, respectively, whereas metastases only occurred from the angiosarcoma and from one borderline phyllodes tumour with five recurrences (5%). In contrast, metaplastic carcinomas gave rise to distant metastases in 50% of cases but no local recurrences. Axillary lymph nodes had been examined in 28 cases, 13 from metaplastic carcinomas. Only two of these showed metastatic spread, both with a pattern similar to the primary tumour. The differences in survival between patients with metaplastic carcinoma and patients with a borderline/malignant phyllodes tumour or a cytokeratin-negative sarcomatous tumour has in this study proven to be highly significant (P < 0.0001), and we find it of importance to use immunohistochemistry in the subclassification of sarcomatous breast tumours for appropriate surgery, reliable prognostic outlook and optimal postoperative therapy.