Histological and Immunohistochemical Evaluation of Ductal Carcinoma In Situ Co-Existing with Triple-Negative Carcinoma of the Breast

Background : Triple-negative breast carcinomas (TNBCs) are associated with high-grade histological tumor and a poor clinical outcome. In this study, we evaluated the histology and immunohistochemical features of DCIS co-existing with TNBC to determine the characteristics of the precursor lesions of TNBC. Methods: Among the 1,610 cases of breast carcinoma, we selected the TINBCs with DCIS (n=196), and compared the pathological and immunohistochemical findings of the DCIS with those of the invasive carcinoma areas. Results : Among the 1,610 breast carcinomas, the TNBCs accounted for 330 cases (20.5%) and there were 196 cases with DCIS. The TN-DCIS cases exhibited high nuclear (94.5%) and histological (94.5%) grades, comedo-necrosis (68.9%) and a small extent of the DCIS-involved area. Immunohistochemically, a p53 expression was present in 48.4% of the TN-DCIS cases and a high Ki-67 index was present in 31.5%. The same TN immunohistochemical profiles as the carcinoma were detected in 109 of the 124 (87.9%) cases, but different profiles were observed in 15 of the 124 (12.1%) cases. The 15 discordant cases were associated with a low histological grade (p=0.037), low p53-positivity (p=0.006) and a low Ki-67 index (p=0.026), as compared to the invasive carcinomas. Conclusions : The results of this study suggest that TN DICIS is a highly probable, but not obligate, precursor lesion of TNBC.