Improved malignancy prediction by B3 breast lesions subclassification.

Core-needle biopsy (CNB) of breast lesions can be classified into 5 categories according to lesion type and associated risk of malignancy. B3 category (lesion of uncertain malignant potential) constitutes a challenging problem in clinical decision, with most ending in excisional biopsy. Therefore, the aim of this study was to establish the incidence of malignancy on excision biopsy of B3 lesions and assess if subclassification (in B3a and B3b categories) according to the presence of atypia in otherwise B3 lesions better predicts malignancy on excision. Forty-eight cases with diagnosis of B3 lesion on CNB and matched surgical excision specimen were included to evaluate the positive predictive value (PPV) and odds for malignancy in CNB. All cases were further subclassified into B3a and B3b categories. B3 category lesions had an overall PPV for malignancy of 12.5% and significant low odds of malignancy of 0.14. When subclassified, B3b (lesions with atypia) demonstrated a higher PPV for malignancy (36.36%) with a nonsignificant odds. Inversely, B3a (lesions without atypia) demonstrated a PPV for malignancy of only 5.41% and a significant low odds of malignancy of only 0.06. The described low rate of malignancy in some of B3 lesions additionally reinforces the practice of avoiding surgical excision in selected patients and provides data that additionally support B3 lesion subclassification according to the presence of atypia. Subclassification of B3 category can further refine the current classification of associated risk of malignancy with possible implications in clinical management.

Cancer stem cells markers CD44, CD24 and ALDH1 in breast cancer special histological types.

AIMS: CD44, CD24 and ALDH1 are the most consistently used biomarkers to identify and characterise the breast cancer stem cell (CSC) phenotype. However, most studies performed until now analysed samples of invasive ductal carcinomas of no special type (IDC-NST). Therefore, prevalence and clinical significance of these CSC markers in breast carcinomas of special histological types (SHT) is largely unknown. For that reason, this study aims to determine the distribution of the breast CD44, CD24 and ALDH1 CSC markers among a series of invasive breast carcinomas of SHT, in comparison with a series of IDC-NST. METHODS: 117 invasive SHT breast carcinomas were analysed for the expression of CD44, CD24 and ALDH1, by immuhohistochemistry. The distribution of these CSC markers was evaluated among the distinct histological special types, and the results were compared with a series of 466 IDC-NST. RESULTS: The expression prevalence of the breast CSC markers differed between special types and IDC-NST. Medullary, papillary and tubular carcinomas were enriched in the CSC phenotype CD44(+)/CD24(-/low) (80.0%, 100.0% and 100.0%, respectively, vs 45.3% in IDC-NST). Considering the ALDH1 cytoplasmic tumour expression, only medullary and metaplastic carcinomas displayed significant increase in CD44(+)/CD24(-/low)/ALDH1(+) CSC phenotype frequency (36.4% and 28.6%, respectively, vs 4.8% in IDC-NST). CONCLUSIONS: The expression distribution of breast CSC markers is largely dependent on histological type. Interestingly, within the distinct SHT, medullary and metaplastic carcinomas are the two types highly associated with high-grade carcinomas, basal-like and claudin-low molecular subtypes, and to the CSC phenotype CD44(+)/CD24(-/low)/ALDH1(+).