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Page 8 of 15 Friedman et al. Plast Aesthet Res 2023;10:23 https://dx.doi.org/10.20517/2347-9264.2022.100

[94]
over the cephalic vein, which allowed us to reliably visualize the lateral upper arm channel . Additionally,
we have more recently added a peri-olecranon injection to visualize another compensatory channel: the
tricipital or Caplan’s pathway [95-99] .

Though we have observed significant variation in baseline lymphatic anatomy between individuals, we have
noticed distinct trends in both the main channels and compensatory lymphatic channels [Figure 4]. In 102
preoperative ICG lymphographies performed, we observed that the main pathways arising from the hand
and forearm (posterior radial, posterior ulnar, anterior radial, and anterior ulnar) often demonstrate a
functional connection to one of two channels in the upper arm: the medial and lateral upper arm
channels . We also noticed variations in the connectivity of the lateral upper arm channel to the forearm
[100]
channels, specifically long and short bundle phenotypes [Figure 5] . The long bundle lateral upper arm
[93]
channel is defined as having a functional connection with a forearm channel, most commonly, the posterior
radial channel. In the short bundle phenotype, the lateral upper arm channel lacks a functional connection
to the forearm channels and is only visualized following the targeted injection over the cephalic vein. Upon
postoperative surveillance of 60 patients who underwent ALND, the short bundle lateral upper arm
[101]
pathway appeared to act as an anatomic risk factor for BCRL . We hypothesize that these findings were
due to the short bundle phenotype resulting in a watershed region of lymphatic drainage between the
forearm and upper arm. We have also observed analogous anatomic phenotypes in the tricipital pathway
[Figure 6]. We believe that future investigations focusing on the anatomical variability of this and other
compensatory channels such as the tricipital pathway, will help patients at the greatest risk for BCRL
[99]
development .

FUTURE DIRECTIONS
This knowledge can be applied clinically at various levels of care in both the preoperative and postoperative
settings. For the lymphatic surgeon, this information may inform which patients would benefit most from
the ILR procedure. Ideally, every patient undergoing ALND would have access to ILR for the prevention of
lymphedema despite their anatomical phenotype, as the morbidity of the procedure is quite low. However,
the relative inaccessibility to lymphatic surgery and inconsistent healthcare coverage for ILR hinders
patients’ ability to access and undergo ILR. Preoperative mapping of lymphatic anatomy using ICG
lymphography can be accomplished in an outpatient clinical setting and does not require a lymphatic
surgeon. Therefore, this is a feasible way to identify patients at the greatest risk for lymphedema
development and for whom ILR would be most beneficial.

Moreover, a better understanding of lymphatic anatomy may inform which lymphatic channels should be
prioritized for bypass or identified with an additional dye, the channels in closer proximity to the axillary
vein. This knowledge would be important not only to the lymphatic surgeon, but also to members of the
tumor board. For example, oncologists may choose to consider anatomical risk when determining a
patient’s neoadjuvant chemotherapy regimen and avoid taxane-based regimens altogether when possible.
Postoperatively, patients with high-risk anatomy can follow a more rigorous lymphedema surveillance
protocol or wear compression garments prophylactically . Additionally, understanding compensatory
[102]
lymphatic channels can help guide both physical therapists and patients in performing manual lymphatic
drainage . Finally, anatomical knowledge can possibly inform radiotherapy planning and field design in
[103]
efforts to protect collateral drainage pathways from radiation exposure .
[104]
Finally, non-surgical methods for the prevention of lymphedema continue to be investigated. The use of
pharmaceuticals that promote lymphangiogensis has been developed as potential treatment for
lymphedema . These drugs could potentially be applied to lymphedema prevention by enabling collateral
[105]