Background: Injection of Technetium 99m sulfur colloid (Tc-99m-SC) into the subareolar lymphatic plexus provides a rapid and reliable method of identifying breast sentinel lymph nodes and their lymphatic connections to the areola, termed sentinel lymphatic channels (SLCs). The objective of this study was to define the anatomic origin, number, and direction of the SLC in relation to the areola after subareolar injection of Tc-99m-SC.
Study design: Using a hand-held goniometer, the exit angle (theta(e)) and direction from the vertical (to the patient's right or left) of SLCs were determined in 87 successful preoperative lymphoscintigrams (46 left breast and 41 right breast).
Results: One major lymphatic trunk was identified in 91% of cases (n = 79), and two lymphatic trunks were identified in 9% of cases (n = 8). Overall, 24% (n = 21) of major lymphatic trunks exited the areola vertically (theta(e) = 0 degrees), 33% (n = 29) exited the areola with theta(e) = right or left 1 to 30 degrees, and 32% (n = 28) exited with a theta(e) = right or left 31 to 60 degrees. In total, 90% (n = 78) of SLCs exited the areola with a theta(e) = right or left 0 to 60 degrees, equivalent to 10 to 12 o'clock in the right breast, and 12 to 2 o'clock in the left breast.
Conclusions: Radial angular measurements of SLCs from preoperative lymphoscintigrams performed by SA injection confirm that the origin of the majority of SLCs is within the upper, outer edge of the areola, and that all SLCs ultimatelytraverse the upper, outer quadrant of the breast and terminate on axillary sentinel nodes.