Microscopic localization of calcifications in and around breast carcinoma: a cautionary note for needle core biopsies.

OBJECTIVE: To detail the microanatomic localization of microcalcifications (Ca++) occurring in association with breast carcinoma and thereby to determine their reliability as a marker of breast carcinoma in small tissue core biopsies. SUMMARY BACKGROUND DATA: Identification of the pathology associated with Ca++ in mammograms has acquired increasing importance in the early detection of breast carcinoma. With recent advances enabling computer-guided stereoscopic needle biopsy of calcified foci, histopathologic diagnosis is rendered on increasingly small tissue samples, raising the risk of misdiagnosis. Knowledge of the microanatomic distribution of Ca++ in relation to diagnostic epithelial elements is essential for assessing their significance in small tissue biopsies.
METHODS: All 32 carcinomas with Ca++ within 1 cm of carcinoma diagnosed by open biopsy at the New England Deaconess Hospital from January 1994 to January 1995 were studied. Ca++ were classified as being within ductal or lobular carcinoma in situ, invasive carcinoma, carcinoma-associated stroma, benign stroma >1 mm from carcinoma, or benign ducts or terminal duct-lobular units. If Ca++ were peritumoral, their distance from the tumor was measured.
RESULTS: Ca++ were present only in malignant components in 31%, only in benign components in 34%, and in both in 34% of cases. The most common locations of Ca++ were benign peritumoral ducts (62%) and ductal carcinoma in situ (54%). The microanatomic distribution of benign peritumoral Ca++ in relation to the mass is detailed.
CONCLUSIONS: In carcinomas with Ca++ in the area of tumor, Ca++ may not be localized to malignant tissue. Caution should be used when interpreting the finding of Ca++ in benign components of small tissue samples of breast masses.