Figure 1. Left lateral dynamic sequence during LymphoBoost (LB) injection: (0 min) Perilesional injection (T=perilesional injection site) was performed approximately 20 min earlier and shows a sentinel node (SN). (1 min) Areolar–cutaneous junction injection (LB) is performed showing activity in syringe during injection. (2 min) Immediately, a very bright focus (pseudosentinel node, PSN) is noted midway between injection sites and the SN from perilesional injection and initially is presumed to be a very bright lymph node. (10 min) An additional focus appears (reverse echelon node, REN), also between the injection sites and the SN from the perilesional injection. (0.6 h to 16 h) The PSN focus fades completely over time while the REN focus persists. End of study view (right image) showing the "sentinel" nodes. The PSN turned out not to represent a node but a lymphatic ectasia (dilation, lake) or possibly even an "end on effect" from a lymphatic channel seen on edge, in effect a "pseudo sentinel node" [5, 14]. The REN persist over time with no fading and most likely represents a node "upstream" and closer to the injection site at the areolar–cutaneous junction, i.e. in effect a "reverse echelon node" [1, 5]. T, perilesional injection site.