Abstract. Full text article available at https://doi.org/10.1093/omcr/omaa070The pathogenesis of metaplastic breast carcinoma (MBC) is still debatable and it has been hypothesized that MBC develops as a result of transformation of epithelial cells into mesenchymal cells along with formation of a favorable tumor microenvironment. This favorable tumor microenvironment helps the transformed cells to undergo further mutations and clonal expansion. Case 1 was a 42-year old female with a 1-year history of a right breast fungating mass which was histologically confirmed to be matrix-producing type of MBC. Case 2 was a 47-year old female who presented with a recurrent left breast mass. Histologically, the tumor was confirmed to be carcinosarcomatous type of MBC. MBC is a rare, heterogeneous tumor with poor prognosis due to its aggressive behavior. It is more likely to mimic other benign breast conditions, therefore contributing to delay of diagnosis as it was for both of our patients herein presented.