Multiple breast carcinomas showing intratumoral heterogeneity: a comparison between histological features of the primary tumor and lymph node metastasis

Abstract

Background Our study aims to analyze the histological profile of lymph node metastases in multiple breast tumors in which primary tumor foci have different histological features. Methods We reassessed slides from consecutive multiple breast carcinomas surgically treated between 2007 and 2012, with complete axillary lymph node dissection. We selected cases with multiple foci displaying different histology and compared them with cases displaying similar histology. Results 155 (19.23%) of 806 cases had multiple breast cancer, of which 23 cases (14.83%) had foci with different morphology and 132 cases had similar morphology. Of the latter, 99 cases had axillary lymph node metastases morphologically identical to the originating breast tumors. Nineteen of the 23 cases with dissimilar morphology (82.6%) had axillary lymph node metastases. In most of these cases (17/19) (89.47%), the metastases had the same histological features as the tumor with the highest histological grade (G3). In 5/19 cases (26.31%), metastases had the features of one of the smaller tumor foci. Conclusions The histology of axillary lymph node metastases in multiple breast carcinomas corresponds to the highest histological grade and/or most aggressive histological type of the primary tumor, which is not necessarily the largest one.