Spindle cell metaplastic carcinoma of breast: A clinicopathological and immunohistochemical analysis

Aim To better characterize spindle cell metaplastic carcinoma (SpCMC) of breast, a rare variant of breast cancer that has been classified under the broad rubric of metaplastic carcinoma. Methods We presented herein 19 cases of metaplastic breast carcinoma with dominant spindle cell component. All cases were clinically of breast origin, showed more than 80% spindle morphology, 10 cases exhibited pure spindled morphology, 8 contained invasive ductal carcinoma (IDC) and 1 presented with ductal carcinoma in situ elements. Results Immunohistochemical studies showed evidence suggesting myoepithelial and epithelial differentiation as exhibited by immunoreactivity for at least one myoepithelial and epithelial markers in all pure spindle cell components. IDC group showed 21.7% of axillary lymph nodes metastasis rate, whereas the axillary lymph node metastasis rate of the SpCMC group was 1.3%, significantly lower than that of the IDC group (P