Metaplastic carcinoma of the breast: A report of two cases along with review of literature

Metaplastic carcinomas of breast are uncommon, representing 0.3% of invasive carcinomas of breast. We are reporting two cases of metaplastic carcinoma breast, one revealing rhabdomyoblastic and spindle cell differentiation and other revealing osteoclast like giant cells. Both were estrogen receptor, progesterone receptor and Her2u negative on immunohistochemistry. Early diagnosis of metaplastic carcinomas is essential as these tumors are usually triple negative and hence, do not respond to transtuzumab. Metaplastic carcinomas typically express HER1/epidermal growth factor receptor (EGFR), thus majority of metaplastic carcinomas are treated with EGFR inhibitors such as geftinib and cetuximab. Also, metaplastic carcinomas are associated with a worse prognosis with a disease free survival rate being 78.1% in metaplastic breast carcinomas compared with 91% in infiltrating duct carcinomas.