Our study aimed to compare the histological tumour type and Nottingham histological grade of invasive tumour foci in multifocal/multicentric breast carcinomas with those in corresponding axillary lymph node (LN) metastases.
We reassessed slides from consecutive multiple breast carcinomas surgically treated with axillary LN dissection (2007-2012).
155 (19.23%) of 806 cases had multiple breast cancer, of which 115 (74.19%) cases had identical morphology. Of these, 85 (73.91%) cases had axillary LN metastases morphologically identical to the originating breast tumours. 32 of the 40 (80%) cases with different morphology had axillary LN metastases; in most heterogeneous cases with differences in grade (87.5%), the grade of metastases was identical to the grade of the tumour foci with the highest histological grade, and in 33.33% of cases the grade in LN was concordant with the grade of smaller foci. Among the 18 cases heterogeneous in histological type with axillary metastases, 33.33% presented heterogeneous histological types in LN, and 22.22% of them were only concordant with the histological type of the smaller tumour foci.
The morphological aspects of axillary LN metastases correspond to the highest histological grade and/or histological tumour type with unfavourable prognosis, which does not necessarily appear in the largest tumour focus.