Clinically occult breast lesions: localization and significance.

From early 1974 through September 1985, 927 needle-guided breast biopsies were performed for clinically occult breast lesions. Two hundred and seventy (29%) of these lesions were malignant. This frequency of malignancy was comparable to a 20% frequency in biopsy samples obtained because of clinical (palpable) findings. Of 142 patients with nonpalpable invasive lesions who underwent axillary dissection, 42 (30%) had histologically confirmed axillary metastases. Although these invasive lesions may be clinically occult, they are not inconsequential and demand appropriate treatment. For those patients in this series undergoing mastectomy, the frequency of multicentric cancer in the same breast was 39%. The past 10 years have witnessed a trend in surgical management away from the standard radical or modified radical mastectomy toward limited surgery and radiation therapy for so-called early breast cancer. When planning treatment for these occult lesions, one must consider their biological potential to metastasize as well as their propensity for multicentricity.