EXPRESSION OF SIALYL-TN IN FINE-NEEDLE ASPIRATES FROM MAMMOGRAPHICALLY DETECTED BREAST-LESIONS - A MARKER OF MALIGNANCY

Malignant transformation is frequently associated with abnormal expres sion of cell surface carbohydrates. Sialyl-Tn (STn) is a core carbohyd rate antigen of tumor-associated mucin formed by the premature 2-6 sia lylation of N-acetylgalactosamine. In an attempt to verify whether thi s antigen is restricted to malignant cells, we studied 30 cases of fin e-needle aspiration (FNA) cytology from mammographically detected brea st lesions. The rationale for choosing this material was the acknowled ged difficulty in diagnosing cytologically small breast lesions, espec ially epithelial intraductal proliferations. The cases were divided in benign lesions (two fibroadenomas and ten ductal hyperplasias) and ma lignant lesions (16 ductal carcinomas). Ten of sixteen malignant cases (62.5%) were positive for STn. Five of fourteen benign cases (35.7%) were also positive for STn (two fibroadenomas and three ductal hyperpl asias). The most consistent positive results in benign lesions resulte d from cases that displayed apocrine metaplasia, although positivity h as also been observed in ductal cells without metaplasia. We did not f ind statistical significant differences among STn expression in benign and malignant breast lesions detected by FNA (P = 0.14). Thus, we con clude that STn is neither specific nor sensitive for detection of mali gnancy in FNA from mammographically detected breast lesions. (C) 1998 Wiley-Liss, Inc.