Mammographic and clinical predictors of drainage patterns in breast lymphoscintigrams obtained during sentinel node procedures.

PURPOSE: The authors' purpose was to explore the association between mammographic findings and drainage patterns on lymphoscintigrams obtained during sentinel node procedures for breast carcinoma.

MATERIALS AND

METHODS

From July 1997 to March 2000, 132 patients with breast cancer who were included in a prospective mammography-pathology correlation and staging database were imaged 2 hours after perilesional injection of 1 mCi filtered (0. 22 microm) Tc-99m sulfur colloid (4 ml volume) before sentinel node procedures.

RESULTS

Sixty-four percent of the scans showed axillary drainage only, 9% showed axillary and internal mammary drainage, and 4% revealed internal mammary drainage only. Twenty-three percent of scans showed no drainage. Of the patients who showed drainage, 17% showed drainage to the internal mammary basin, and 5% showed this exclusively. Internal mammary drainage was seen in 18% (10 of 57) of lateral, 21% (6 of 29) of medial, and 14% (1 of 7) of subareolar lesions (P = NS). No drainage was seen in 22% of patients with predominantly fatty mammographic parenchymal density (>50%) compared with only 8% of patients with predominantly dense (>50%) parenchyma (P < 0.05). Failure to show drainage was more common in women older than 50 years (P < 0.05). Axillary sentinel nodes were identified surgically in 73% of patients with negative scan findings. There was no significant association between scintigraphic drainage and mammographic soft tissue tumor size and appearance, histologic findings, or axillary node status.

CONCLUSIONS

Dense mammographic parenchyma and age less than 50 years are associated with identification of lymphatic drainage on lymphoscintigrams performed before sentinel node procedures in 91% to 92% of patients. Internal mammary drainage, present in 18% of lateral and 21% of medial lesions, may direct therapy to include internal mammary lymph nodes.