Breast carcinoma with osseous metaplasia: an electron microscopic study

A breast carcinoma containing osseous metaplasia was examined with electron microscopy. The heterologous components were intermingled closely with the usual infiltrating ductal type of a breast carcinoma. Ultrastructurally, carcinoma cells were distinguished clearly from the various mesenchymal cells composed of active fibroblasts, osteoblasts, and osteoclasts. No intermediate cells were present between the two distinct cell populations. Our findings are consistent with the stromal cell origin of the heterologous components and are discussed with relation to their histogenesis in breast carcinoma.