Singhal lab
The R01 Variable Anatomy and Function study aims to identify normal variations in lymphatic anatomy (different arrangements of vessels, or pathways, through which excess fluid travels out of the arms) and function that predispose women to lymphedema.  
Boston Lymphatic Center Team
September 2023
The main lymphatic channels of the arm terminate in the axilla and would be disrupted during an ALND.
However, secondary or collateral pathways have also been described which variably terminate in the axilla or drainage basins outside the axilla (e.g. supraclavicular nodes). These would be spared by an ALND. 
Secondary pathways act as a back-up pathway for the drainage of the arm, especially in the event of damage to the primary drainage pathway. 
Breast cancer related lymphedema affects 1.2 million patients in the U.S. and is one of the most significant cancer survivorship burdens.
Lymphedema usually follows the removal of lymph nodes during an axillary lymph node dissection (ALND), a common procedure performed during breast cancer treatment.    
A breast cancer patient will experience a “double hit” if they undergo an ALND and subsequent surgical disruption or radiation injury to these secondary pathways during breast cancer treatment. The “double hit” could predispose patients to post-operative lymphedema.  
The main lymphatic pathways (blue arrow) drain to the axilla. The M-S pathway (red arrow) bypasses the axillary nodes. Adapted from Sappey (published 1874).
The main secondary pathway of the arm was originally described by anatomists Mascagni in 1787 and by Sappey in 1874. 
Termed the Mascagni-Sappey (M-S) pathway, anatomists Kubik and Leduc in the 1900s clarified its presence in the posterior upper arm adjacent to the cephalic vein.  
 
The M-S pathway has been described as a “compensatory” pathway for lymphatic drainage of the limb, underscoring its importance in patients who have damage to their main drainage pathways after ALND or radiation.
This study has two primary aims:  
1
Define an alternative lymphatic route, the M-S pathway, in the upper extremity of healthy female volunteers. 
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These volunteers do not have a history of lymphedema or ALND surgery.  
2
Define the M-S pathway anatomy after axillary lymph node dissection (ALND) surgery in breast cancer patients without lymphedema.
These volunteers are at least 2 years post ALND surgery and have not developed lymphedema.  
This exam uses a combination of dye called indocyanine green (ICG) that glows at certain wavelengths and a special camera that can capture images and video illuminated by the dye.
This method is used to visualize lymphatic shallow vessels underneath the skin.  
Key
Lateral upper arm
Tricipital
Posterior radial
Posterior ulnar
Anterior radial
Anterior ulnar
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Cephalic and basilic vein
deltotricipital & deltopectoral groove
SPECT/CT stands for single-photon-emission computed tomography.
This scan consists of combining a CT scan (which lets us see your anatomy clearly) with a scan that tracks the progression of a tracer through that anatomy over a certain period of time. It lets us see the volunteer's anatomy with clarity as the tracer moves through.  
Images courtesy Kevin Donohoe, MD
