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PURPOSE:
Development of lymphedema following axillary lymph node biopsy is well known. However, even after the sentinel node biopsy, lymphedema can occur, suggesting a close relationship between the breast and the upper extremity lymphatic systems. Unfortunately, the anatomy of the human lymphatics is not fully understood. Current understanding of the pattern of lymph drainage is still largely dependent on the anatomical studies performed in the nineteenth century. The aim of this study is to reappraise the gross anatomy of the lymphatic system in the upper limb and breast region, and their relationship using animal carcasses and human cadavers.
METHODS:
19 upper limbs, 12 anterior upper torsos and 3 forequarters fresh human cadaver specimens and 6 forequarters dog specimens were investigated. The technique used hydrogen peroxide with/without dye to identify lymphatic vessels and to dilate them. The individual channels were injected with radio-opaque lead oxide mixture with intralymphatic microinjection technique and recorded on radiographs. Each channel was meticulously dissected under the surgical microscope and its course traced in relation to its nodes.
RESULTS:
In human cadaver studies, most of the superficial lymph vessels on the upper limb, especially on the anterior side, flowed into one dominant lymph node in the axillary region. Lateral arm lymphatic bundle, which ran along the cephalic vein, bypassed the axillary nodes and connected to the deltopectral node en route to the supra and/or subclavicular node. On the posterior side, some lymphatic vessels bypassed the main node and drained straight into the second tier nodes. On the anterior upper torso, the superficial lymphatic pathways showed no significant difference between male and female. Most of them passed over and through breast parenchyma. On the forequarter studies in dogs, the main node identified on the upper limb studies also covered a wide range of the anterior upper torso. Major difference between human and canine lymphatic system was the size of the lateral arm territory which drained to the clavicular node: this territory in dog was much larger than that in human. Of note, one main axillary node in dog received the lymphatic vessels from the medial side of upper limb as well as anterior upper torso, similar to our human cadaver results.
CONCLUSION:
We were able to demonstrate, using a novel microsurgical injection and radiographic method, a close relationship between the lymphatic system of the upper limb and anterior torso. Both in human and canine models, the main lymph node in the axilla was the sentinel node for both medial side of the upper extremity and the breast. These updated anatomic findings help us to understand why lymphedema may still develop following the sentinel node biopsy in breast cancer patients.