Variable Anatomy of the Lateral Upper Arm Lymphatic Channel: An Anatomical Risk Factor for Breast Cancer–Related Lymphedema

BACKGROUND: The lateral upper arm channel is an accessory lymphatic pathway that drains the upper extremity by means of the deltopectoral groove and supraclavicular nodes, thereby bypassing the axilla. Its variable connectivity to the forearm has not been studied in vivo. METHODS: Indocyanine green (ICG) lymphography was performed preoperatively to map the superficial and functional arm lymphatics in breast cancer patients without clinical or objective evidence of lymphedema. A retrospective review was performed to extract demographic, ICG imaging, and surgical data. RESULTS: Sixty patients underwent ICG lymphography before axillary lymph node dissection between June of 2019 and October of 2020. In 59%, the lateral upper arm lymphatic channel was contiguous with the forearm (long bundle). In 38%, the lateral upper arm lymphatic channel was present but not contiguous with the forearm (short bundle). In 3%, the lateral upper arm pathway was entirely absent. Seven patients developed at least one sign of lymphedema during postoperative surveillance, of which 71% demonstrated the short bundle variant. CONCLUSION: Although the lateral upper arm pathway is most often present, its connections to the forearm are frequently absent (short bundle), which, in this pilot report, appears to represent a potential risk factor for the development of lymphedema. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, V.