Calcium oxalate is associated with benign breast tissue. Can we avoid biopsy?

Breast biopsies are commonly performed for abnormal, usually clustered, calcifications detected by mammography. Calcium phosphate is the predominant form of calcium seen in breast tissue and is frequently associated with malignancy. Calcium oxalate, which can also be present in breast tissue, has been exclusively associated with benign lesions. Thus, if mammography could distinguish calcium phosphate from calcium oxalate, biopsy could be avoided in some patients. Pathologic findings and corresponding mammograms of 55 patients who underwent biopsy for abnormal calcifications were reviewed. The authors evaluated such pathologic features as type of calcification, anatomic location, and association with fibrocystic changes or carcinoma. Mammographically, calcifications were categorized by size, distribution, and morphology, and each was assigned a density rating of low, medium, or high. Of the 55 cases, 41 contained calcium phosphate only, 8 contained calcium oxalate only, and 6 contained both. If only calcium oxalate was present, the calcium was always associated with benign epithelium. Of 47 cases, calcium phosphate was associated with benign breast disease in 28 and with carcinoma in 19. Five of six cases with both calcium phosphate and calcium oxalate contained carcinoma; calcium phosphate was seen in the carcinoma area in all five. Radiologically, calcium phosphate was typically medium to high density, whereas calcium oxalate was characterized as amorphous, low to medium density. Other low-density calcifications were almost always benign, unless pleomorphic in shape. Although further work is necessary to confirm these findings, it appears that, radiologically, low-density, amorphous, calcifications, even if clustered, are associated with benign breast disease, and may represent calcium oxalate. Patients with such calcifications may be managed conservatively.