Undifferentiated Sarcoma of the Breast

Undifferentiated Sarcoma of the Breast

Primary sarcoma of the breast is extremely rare and it is a diagnosis of exclusion, notably metaplastic carcinomas and malignant phyllodes tumors. We present a case of 53-year old Korean female with undifferentiated pleomorphic sarcoma with CD10 expression. It was a high grade tumor composed of spindle cells, and immunohistochemical analysis revealed negativity for cytokeratins and CD34, but focal positivity for actin, diffuse positivity for CD10 and vimentin. These results led to the diagnosis of undifferentiated pleomorphic sarcoma. This case represents a rare variant of primary breast sarcoma which imposes a diagnostic difficulty, and highlights the importance of CD10 expression.