Spindle cell carcinoma of the breast.

Spindle cell carcinoma is a rare breast tumor. We present herein three cases of spindle cell carcinoma of the breast and review its characteristics from the literature. Spindle cell carcinoma frequently forms a large and well-circumscribed tumor with gross cyst formation. Histologically, its dominant component is of sheets of spindle shaped cells, and it includes such contiguous carcinoma components as squamous differentiation or invasive ductal carcinoma. Estrogen receptor expression and lymph node metastasis tend to be low. Despite the sarcomatous features, spindle cells are likely to be derived from epithelial cells of mammary glands. Immunohistochemical and ultrastructural examination demonstrated the expression of keratin and the desmosome-like junctional structure in the spindle cell components. Relatively favorable prognosis is expected in spindle cell carcinoma of the breast compared to common breast carcinoma.