Real-Time Visualization of the Mascagni-Sappey Pathway Utilizing ICG Lymphography

Background: Anatomic variations in lymphatic drainage pathways of the upper arm may have an important role in the pathophysiology of lymphedema development. The Mascagni-Sappey (M-S) pathway, initially described in 1787 by Mascagni and then again in 1874 by Sappey, is a lymphatic drainage pathway of the upper arm that normally bypasses the axilla. Utilizing modern lymphatic imaging modalities, there is an opportunity to better visualize this pathway and its potential clinical implications. Methods: A retrospective review of preoperative indocyanine green (ICG) lymphangiograms of consecutive node-positive breast cancer patients undergoing nodal resection was performed. Lymphography targeted the M-S pathway with an ICG injection over the cephalic vein in the lateral upper arm. Results: In our experience, the M-S pathway was not visualized in 22% (n = 5) of patients. In the 78% (n = 18) of patients where the pathway was visualized, the most frequent anatomic destination of the channel was the deltopectoral groove in 83% of patients and the axilla in the remaining 17%. Conclusion: Our study supports that ICG injections over the cephalic vein reliably visualizes the M-S pathway when present. Further study to characterize this pathway may help elucidate its potential role in the prevention or development of upper extremity lymphedema.