How can we better distinguish metastatic tumors from primary tumors in the breast?

Thus, combined results of breast-related and extramammary organ/tumor-specific markers can be helpful to distinguish between primary and metastatic tumors and to indicate the possible primary site or tumor type of metastatic tumors. The prior/concomitant cancer history, histology, I in situ i carcinoma component, and immunophenotype constitute four diagnostic clues to suspect and diagnose metastatic tumors. Regarding the I in situ i carcinoma component, pathologists should be aware of I in situ i -mimicking structures in metastatic tumors and should not exclude the possibility of metastatic tumors. [Extracted from the article]