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Page 6 of 8 Hosomi et al. Plast Aesthet Res 2023;10:60 https://dx.doi.org/10.20517/2347-9264.2023.77

[7]
shunts . This forms the basic mechanism of conventional VLNT in lymphedema treatment; the congestive
lymphatic fluid is drained to the transferred lymph nodes and then flows out to drainage veins via lymph-
venous shunts inside the lymph nodes [7,11] . However, there is the possibility of the sclerosis of lymph nodes
[15]
following conventional VLNT due to efferent lymphatic vessel obstruction . In addition, in our
experiences, the conventional VLNT is not often effective enough to improve the severe lymphedema
extremities, which leads to the need for and idea of lymphatico-lymphatic anastomosis. One of the major
limitations of conventional VLNT is the ineffective utilization of the original efferent lymphatic vessels,
which may cause efferent lymphatic channel obstruction and lymph node sclerosis postoperatively. Efferent
lymphatic occlusion leads to sclerosis of lymph nodes and finally results in lymph node dysfunction .
[16]
Therefore, we considered that long-term improvement of lymphedema requires the reconstruction of
physiological lymphatic flow and sufficient vascularization. In this case, we established a new drainage
pathway not only to the veins but also to the lymphatics, which is more natural and physiological compared
to conventional LT.

The lymphatic system has a superficial network above the deep fascia and a deep system below the deep
fascia [17,18] . Connections between the superficial and deep lymphatic systems are considered to be few, and
therefore, the deep system is less influenced by the condition of the superficial system [19,20] . There are no
previous reports of reconstructing new drainage routes between the superficial system and the deep system.
Our method established a new lymphatic drainage bypass to the internal mammary lymphatics, a part of the
deep lymphatic system, which may have, in turn, contributed to obtaining effective lymphatic flow.

The transplanted lymphatics in this report provided active transportation of lymphatic fluid, as confirmed
by ICG lymphography. When lymphatics are non-vascularized, the lymphatic vessels can only work as a
simple conduit and do not have the ability to actively transport lymphatic fluid . The adipose tissue
[16]
surrounding transferred lymphatics helps maintain sufficient vascularization, which could have a positive
effect on smooth muscle cells, and VLNT develops the potential of rich lymphatic discharge, which may
help facilitate lymphangiogenesis [21-23] . In the congestive lymphatics of edematous extremities, smooth
muscle cells degenerate, which causes the loss of lymphatic dynamic function [3,24] . Therefore, abundant
vascularity contributes to functional lymphatics, which may, in turn, enhance lymphangiogenesis in
surrounding soft tissue.

Our method has several disadvantages. Firstly, our method requires supermicrosurgical technique for
dissection and anastomosis. In this case, the elevation of the superficial branch-based SCIP flap, internal
mammary vessel perforator-to-perforator anastomosis, and most notably, the efferent lymphatico-
lymphatic anastomosis which included lymphatic vessels less than 0.5 mm required supermicrosurgical
technique. The use of IVaS technique enabled us to perform safe and precise end-to-side
supermicrosurgical anastomosis . During such challenging anastomosis involving small vessels where
[13]
insertion of forceps into the vessel lumen may not be possible, IVaS stents allow traction and distinction of
the vessel lumen, thereby preventing inadvertent catching of the back wall and ensuring patency of the
anastomosis. Secondly, there is a possibility that the recipient lymphatic vessel cannot be found
appropriately. In such a case, lymphatico-venous anastomosis would be one of the options, which cannot be
the reconstruction of physiological lymphatic flow but can provide lymphatic flow postoperatively [10,15] .
Thirdly, the inclusion of an inguinal lymph node in our flap raises the possibility of postoperative
lymphedema at the donor site. To address this, we used intraoperative ICG lymphography, patent blue
navigation, and supermicrosurgical technique to resect only one lymph node and preserve other lymph
nodes. This cautious approach may have contributed to preventing postoperative donor site lymphedema in
our patient.