Interval changes in nonpalpable breast lesions as an indication of malignancy

To determine whether the patterns of interval changes in nonpalpable breast lesions can be used to determine malignancy.

The authors reviewed the records for 128 nonpalpable breast lesions detected by mammography between March 1990 and May 1992 for which previous imaging studies were available. Changes in size, density and contour of the 59 masses and changes in size, number, configuration and pattern for the 69 cases involving microcalcifications were determined from comparison of the current mammograms with the earlier imaging studies, obtained 6 to 42 months previously. These findings were correlated with the pathological diagnosis based on needle localization and excisional biopsy.

Twelve (55%) of the 22 new masses and 15 (48%) of the 31 masses that changed were malignant, but none of the 6 masses that did not change were malignant (chi 2 test, p < 0.01). All of the 31 masses that changed increased in size (and of these, 15 [48%] were malignant). In addition, 14 (45%) of the masses that changed exhibited increased density (and of these 9 [64%] were malignant), and 11 (35%) became irregular (and all of these were malignant). Eight (47%) of the 17 cases of new calcifications, 18 (43%) of the 42 cases of calcifications that changed and none of the 10 cases of unchanged calcifications were malignant (chi 2 test, p < 0.01). Twelve (44%) of the 27 calcifications that changed in area and 14 (40%) of the 35 that changed in number were malignant. Fifteen (60%) of the 25 calcifications that changed from scattered to grouped and 8 (53%) of the 15 that changed from punctate to linear were malignant.

A change in the density or contour of a mass is a fairly definite sign of malignancy. The authors conclude that interval observation is a good method of detecting malignancy in breast masses but is less reliable for detecting malignancy in calcifications.