Introduction: Osteopontin, a non-collagen, Ca-binding phosphoprotein, plays roles in both physiological and pathological mineralisation processes. Its expression may be severely altered in malignant tumours.
Aim: To investigate the presence of this protein in breast tumours showing mammographic microcalcifications.
Material: In this study the authors investigated immunohistochemically the osteopontin expression in 26 breast tumours. The elemental composition of the microcalcifications of the same tumours was also examined with energy dispersive spectrometer linked to a scanning electron microscope.
Results: Osteopontin expression was found within the tumours in the tumour cells, in vascular smooth muscle cells, in the myoepithelial cells of the normal ducts, and in macrophages. Extracellular osteopontin positivity was seen around calcified foci. There was no correlation between osteopontin positivity and the examined prognostic factors: grade, type and size of the tumour, axillary lymph nodes status, or age. Two types of microcalcifications were seen: 1. Ca-phosphate only, 2. Those composed of various other elements.
Conclusion: The presence of osteopontin in the vicinity of calcified foci and in the vessel walls seems to support the hypothesis that osteopontin takes part in calcification process.