Functional lymphatic anatomy for sentinel node biopsy in breast cancer: echoes from the past and the periareolar blue method

Abstract

Objective: To simplify and improve the technique of axillary sentinel node biopsy, based on a concept of functional lymphatic anatomy of the breast.

Summary background data: Because of their common origin, the mammary gland and its skin envelope share the same lymph drainage pathways. The breast is essentially a single unit and has a specialized lymphatic system with preferential drainage, through select channels, to designated (sentinel) lymph nodes in the lower axilla.

Methods: These hypotheses were studied by comparing axillary lymph node targeting after intraparenchymal peritumoral radiocolloid (detected by a gamma probe) with the visible staining after an intradermal blue dye injection, either over the primary tumor site (90 procedures) or in the periareolar area (130 procedures). The radioactive content, blue coloring, and histopathology of the individual lymph nodes harvested during each procedure were analyzed.

Results: Radiolabeled axillary nodes were identified in 210 procedures, and these were colored blue in 200 cases (94%). The targeting concordance between peritumoral radiocolloid and intradermal blue dye was unrelated to the breast tumor location or the site of dye injection. Radioactive sentinel nodes were not stained blue in 10 procedures (5%), but this mismatching could be explained by technical problems in all cases. In two cases (1%), the (pathologic) sentinel node was blue but had no detectable radiocolloid uptake.

Conclusions: The lessons learned from this study provide a functional concept of the breast lymphatic system and its role in metastasis. Anatomical and clinical investigations from the past strongly support these views, as do recent sentinel node studies. Periareolar blue dye injection appears ideally suited to identify the principal (axillary) metastasis route in early breast cancer. Awareness of the targeting mechanism and inherent technical restrictions remain crucial to the ultimate success of sentinel node biopsy and may prevent disaster.

Figure 1. Two blue (axillary) lymphatic trunks clearly visible after periareolar intradermal blue dye injection. The vessels pass over the breast tissue and join to drain into a single blue sentinel node (held in the forceps) in the lower axilla.

Figure 2. Tumor location in 220 procedures: distribution among the different breast quadrants. (UOQ, upper outer quadrant; LOQ, lower outer quadrant; C, central; UIQ, upper inner quadrant; LIQ, lower inner quadrant.)

Figure 3. Concordance between sentinel node uptake of peritumoral radiocolloid and intradermal blue dye: (A) in group 1, blue dye was injected at the tumor site (90 procedures); (B) in group 2, blue dye was injected in the periareolar area (130 procedures).