Spindle cell carcinoma of the breast.

A case of spindle cell carcinoma of the breast in association with myoepithelial cell hyperplasia is presented. Immunocytochemistry demonstrated labelling of tumour cells for cytokeratin, vimentin and S-100 protein. Electronmicroscopy showed desmosomes and bundles of tonofilaments as well as fine filaments in the cytoplasm. The findings in the present case point to the metaplastic spindle cell nature of squamous carcinoma of the breast. The possible role of myoepithelial cells in the origin of the spindle cell component is discussed.