Surgery for nonpalpable breast lesions.

Nonpalpable lesions detected on mammograms were localized in 475 women between 1976 and 1988 by means of the spot method. A malignant neoplasm was noted in 149 patients (31%), including 69 (33%) of 206 with clusters of microcalcifications, 16 (41%) of 39 with calcifications associated with densities and 64 (28%) of 230 with nonpalpable masses. Infiltrating lesions were present in 89 (60%) of 149 patients. Among women with infiltrating lesions who had axillary dissection, 14 (21%) of 67 had positive nodes. In younger women, microcalcifications were more likely to represent neoplasms, masses frequently represented invasive tumors. Among patients with invasive malignant neoplasms who had calcifications, 39% had positive axillary lymph nodes. Spot localization, rather than monitoring, seems appropriate in young women with microcalcifications suggestive of malignant neoplasms and older patients with nonpalpable masses to achieve earlier and more effective treatment of biologically significant occult neoplasms.