Breast tumors: composition of microcalcifications.

The authors investigated the crystallographic patterns of calcifications in breast tissue from 31 patients, including eight calcified benign lesions, 17 calcified carcinomas, and six noncalcified control samples. Scanning electron microscopy, energy-dispersive x-ray analysis, and x-ray diffraction with the Guinier camera were employed and yielded information on the shape and composition of breast calcifications. Polyhedral crystals (with energy-dispersive x-ray analysis response to calcium) contained calcite, aragonite, or calcium oxalate, depending on the case. Calcium oxalate crystals were found only in malignant breast tissues. Spherical crystals (with energy-dispersive x-ray analysis response to calcium and phosphorus) contained apatite. Spherical crystals predominated in malignant processes, but all shapes and compositions were present in both benign and malignant processes. The relationship of the calcification to its surrounding tissue may account for differences in structure, but results are inconclusive and require further study.