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

Objective To simplify and improve the technique of axillary sentinel node b iopsy, based on a concept of functional lymphatic anatomy of the breast. Summary Background Data Because of their common origin, the mammary gland a nd its skin envelope share the same lymph drainage pathways. The breast is essentially a single unit and has a specialized lymphatic system with prefe rential drainage, through select channels, to designated (sentinel) lymph n odes in the lower axilla. Methods These hypotheses were studied by comparing axillary lymph node targ eting after intraparenchymal peritumoral radiocolloid (detected by a gamma probe) with the visible staining after an intradermal blue dye injection. e ither over the primary tumor site (90 procedures) or in the periareolar are a (130 procedures). The radioactive content, blue coloring, and histopathol ogy of the individual lymph nodes harvested during each procedure were anal yzed. Results Radiolabeled axillary nodes were identified in 210 procedures, and these were colored blue in 200 cases (94%). The targeting concordance betwe en peritumoral radiocolloid and intradermal blue dye was unrelated to the b reast tumor location or the site of dye injection, Radioactive sentinel nod es were not stained blue in 10 procedures (5%), but this mismatching could be explained by technical problems in ail cases. In two cases (1%), the (pa thologic) sentinel node was blue but had no detectable radiocolloid uptake. Conclusions The lessons learned from this study provide a functional concep t 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 ideall y suited to identify the principal (axillary) metastasis route in early bre ast cancer. Awareness of the targeting mechanism and inherent technical restrictions re main crucial to the ultimate success of sentinel node biopsy and may preven t disaster.