Multiple (multicentric and multifocal) cancers in the ipsilateral breast with different histologies: profiles of...

Chromosomal numerical abnormality (CNA) is a characteristic of breast cancer as with other common solid cancers. Multiple mammary carcinomas are also sometimes encountered in the ipsilateral breast. Deciding whether they are multicentric (arising independently) or multifocal (of the same origin) has been a continued challenge to clinicians and pathologists.

We experienced two cases of macroscopically distinct double carcinomas in the ipsilateral breast, in which two cancers had a different histopathological morphology. Centromere probes identifying 17 different and specific centromeres were used to obtain the profile of CNA for each tumor, with a microwave-assisted FISH protocol. For comparison, a case of three lesions, two of which had the same and the other different histology was also studied.

Contrary to our expectations, in spite of the particular difference in the histopathological picture of these tumors, the CNA profile was the same in one case and different in the other. The gain of chromosome 1 and loss of chromosome 15 are representative features shared by multifocal cases. On the other hand, the multiple cancers with the same histology had mostly the same CNA profile.

CNA profiling is useful to identify the lineage of multiple breast cancers. As shown here, regardless of the histological features, a certain common CNA profile can define the same origin of some multiple cancers.