The All but Forgotten Mascagni-Sappey Pathway: Learning from Immediate Lymphatic Reconstruction

Mapping the Anatomy of the Human Lymphatic System

BACKGROUND

 While substantial anatomical study has been pursued throughout the human body, anatomical study of the human lymphatic system remains in its infancy. For microsurgeons specializing in lymphatic surgery, a better command of lymphatic anatomy is needed to further our ability to offer surgical interventions with precision. In an effort to facilitate the dissemination and advancement of human lymphatic anatomy knowledge, our teams worked together to create a map. The aim of this paper is to present our experience in mapping the anatomy of the human lymphatic system.

METHODS

 Three steps were followed to develop a modern map of the human lymphatic system: (1) identifying our source material, which was "Anatomy of the human lymphatic system," published by Rouvière and Tobias (1938), (2) choosing a modern platform, the Miro Mind Map software, to integrate the source material, and (3) transitioning our modern platform into The Human BioMolecular Atlas Program (HuBMAP).

RESULTS

 The map of lymphatic anatomy based on the Rouvière textbook contained over 900 data points. Specifically, the map contained 404 channels, pathways, or trunks and 309 lymph node groups. Additionally, lymphatic drainage from 165 distinct anatomical regions were identified and integrated into the map. The map is being integrated into HuBMAP by creating a standard data format called an Anatomical Structures, Cell Types, plus Biomarkers table for the lymphatic vasculature, which is currently in the process of construction.

CONCLUSION

 Through a collaborative effort, we have developed a unified and centralized source for lymphatic anatomy knowledge available to the entire scientific community. We believe this resource will ultimately advance our knowledge of human lymphatic anatomy while simultaneously highlighting gaps for future research. Advancements in lymphatic anatomy knowledge will be critical for lymphatic surgeons to further refine surgical indications and operative approaches.

Distally Based Lymphatic Microsurgical Preventive Healing Approach-A Modification of the Classic Approach

The treatment of breast cancer has seen great success in the recent decade. With longer survivorship, more attention is paid to function and aesthetics as integral treatment components. However, breast cancer-related lymphedema (BCRL) remains a significant complication. Immediate lymphatic reconstruction is an emerging technique to reduce the risk of BCRL, the Lymphatic Microsurgical Preventive Healing Approach (LYMPHA) being the most widely used approach. Despite promising results, it is often difficult to find suitably sized recipient venules and perform the microanastomoses between mismatched vessels deep in the axilla. Moreover, high axillary venous pressure gradients and potential damage from radiotherapy may affect the long-term patency of the anastomoses. From an ergonomic point of view, performing lymphaticovenular anastomosis in the deep axilla may be challenging for the microsurgeon. In response to these limitations, we modified the technique by moving the lymphatic reconstruction distally-terming it distally based LYMPHA (dLYMPHA). A total of 113 patients underwent mastectomy with axillary clearance in our institution from 2018 to 2021. Of these, 26 underwent subsequent dLYMPHA (Group 2), whereas 87 did not (Group 1). In total, 17.2% (15 patients) and 3.84% (1 patient) developed BCRL in Groups 1 and 2, respectively ( p  = 0.018). Lymphatics and recipient venules suitable for anastomoses can be reliably found in the distal upper limb with better size match. A distal modification achieves a more favorable lymphaticovenular pressure gradient, vessel match, and ergonomics while ensuring a comparably low BCRL rate.

Immediate lymphatic reconstruction: Lessons learned over eight years

Immediate lymphatic reconstruction (ILR) is recognized as a surgical approach used to reduce the risk of developing secondary lymphedema, and evidence demonstrating the efficacy of ILR is favorable. Our Lymphatic Center has become a centralized location offering ILR for the risk-reduction in breast cancer-related lymphedema (BCRL) in New England. Over the course of our experience, we made several modifications and adapted our approach to enhance the operative success of this procedure. These include advancements in our use of indocyanine green (ICG) imaging to identify baseline lymphatic anatomical variation, utilization of fluorescein isothiocyanate for lymphatic vessel visualization, application of the lymphosome concept to guide arm injection sites, verification of anastomotic patency (using ICG), localization of reconstruction to guide radiation therapy, incorporation of intraoperative tools to facilitate better anatomic visualization of the axilla, and addition of a lower extremity vein graft to mitigate venous-related complications. Collecting information from each surgery in a standardized manner, including intraoperative lymphatic channel measurements, and deploying clips for possible future radiation exposure, enables future studies on ILR patient outcomes. In this contribution, we aimed to share our institutional modifications with the surgical community to facilitate further adoption, conversation, and advancement of ILR for the risk-reduction in BCRL.

Immediate Lymphatic Reconstruction in 77 Consecutive Breast Cancer Patients: 2-year Follow-up

BACKGROUND

 Breast cancer-related lymphedema (BCRL) is a cyclical, progressive disease that begins at the time of axillary dissection and worsens in the setting of adjuvant oncologic therapies. The paradigm of lymphedema management in these patients is shifting from therapeutic surgeries and decongestive therapy to preventative surgery with immediate lymphatic reconstruction (ILR).

METHODS

 After institutional review board approval, a prospective database was maintained of all patients undergoing ILR. Patients were excluded if they had preoperative lymphedema or expired during the study period. All ILR were performed by the senior author. A control group was established with standardized physician delivered phone surveys of patients who had axillary dissection for breast cancer (same oncologic surgeon cohort) prior to the implementation of ILR at the same institution. The study and control groups were matched based on history of adjuvant radiation and body mass index.

RESULTS

 A cohort of patients between 2016 and 2019 with 2 years of follow-up after undergoing ILR (77 patients) were matched with those who did not undergo lymphatic reconstruction (94 patients). The incidence of lymphedema in the study group undergoing ILR was 10% (N = 8). In comparison, the incidence in the cohort who did not undergo lymphatic reconstruction was 38% (N = 36; p < 0.01). Patients with ILR had 92% lower odds of developing lymphedema (p < 0.01).

CONCLUSION

 ILR can significantly reduce the risk of developing BRCL in high-risk patients at 2 years of follow-up. Patients receiving adjuvant radiation therapy are more likely to develop BCRL after ILR compared with those who do not. Ongoing studies include investigation aimed at identifying patients most at risk for the development of BRCL to help target intervention as well as elucidate factors that contribute to the success of ILR.

Alternative Lymphatic Drainage Pathways in the Trunk Following Oncologic Therapy

BACKGROUND

Anatomic and functional descriptions of trunk and breast lymphedema following breast cancer treatment are emerging as indicators of lymphatic dysfunction. Indocyanine green-lymphangiography has been instrumental in characterizing this dysfunction in the extremity and can be applied to other regions. Previous work has established a validated Pittsburgh Trunk Lymphedema Staging System to characterize such affected areas. This study aims to identify risk and protective factors for the development of truncal and upper extremity lymphedema using alternative lymphatic drainage, providing implications for medical and surgical treatment.

METHODS

Patients undergoing revisional breast surgery with suspicion of upper extremity lymphedema between 12/2014 and 3/2020 were offered lymphangiography. The breast and lateral/anterior trunks were visualized and blindly evaluated for axillary and inguinal lymphatic flow. A linear-weighted Cohen's kappa statistic was calculated comparing alternative drainage evaluation. Binomial regression was used to compute relative risks (RRs). Significance was assessed at alpha = 0.05.

RESULTS

Eighty-six sides (46 patients) were included. Twelve sides underwent no treatment and were considered controls. Eighty-eight percent of the noncontrols had alternative lymphatic flow to the ipsilateral axillae (64%), ipsilateral groins (57%), contralateral axillae (20.3%), and contralateral groins (9.3%). Cohen's kappa for alternative drainage was 0.631 ± 0.043. Ipsilateral axillary and contralateral inguinal drainage were associated with reduced risk of developing truncal lymphedema [RR 0.78, confidence interval (CI) 0.63-0.97, P = 0.04; RR 0.32, CI 0.13-0.79, P = 0.01, respectively]. Radiation therapy increased risk of truncal and upper extremity lymphedema (RR 3.69, CI 0.96-14.15, P = 0.02; RR 1.92, CI 1.09-3.39, P = 0.03, respectively). Contralateral axillary drainage and axillary lymph node dissection were associated with increased risk of upper extremity lymphedema (RR 4.25, CI 1.09-16.61, P = 0.01; RR 2.83, CI 1.23-6.52, P = 0.01, respectively).

CONCLUSIONS

Building upon previous work, this study shows risk and protective factors for the development of truncal and upper extremity lymphedema. Most prevalent alternative channels drain to the ipsilateral axilla and groin. Ipsilateral axillary and contralateral inguinal drainage were associated with reduced risk of truncal lymphedema. Patients with radiation, axillary dissection, and contralateral axillary drainage were associated with increased risk of upper extremity lymphedema. These findings have important clinical implications for postoperative manual lymphatic drainage and for determining eligibility for lymphovenous bypass surgery.

The emerging importance of lymphatics in health and disease: an NIH workshop report

The lymphatic system (LS) is composed of lymphoid organs and a network of vessels that transport interstitial fluid, antigens, lipids, cholesterol, immune cells, and other materials in the body. Abnormal development or malfunction of the LS has been shown to play a key role in the pathophysiology of many disease states. Thus, improved understanding of the anatomical and molecular characteristics of the LS may provide approaches for disease prevention or treatment. Recent advances harnessing single-cell technologies, clinical imaging, discovery of biomarkers, and computational tools have led to the development of strategies to study the LS. This Review summarizes the outcomes of the NIH workshop entitled "Yet to be Charted: Lymphatic System in Health and Disease," held in September 2022, with emphasis on major areas for advancement. International experts showcased the current state of knowledge regarding the LS and highlighted remaining challenges and opportunities to advance the field.

Accessory Lymphatic Drainage Pathways on Indocyanine Green Lymphography in Patients with Breast Cancer-Related Lymphedema

BACKGROUND

Current predictive models of lymphedema risk cannot predict with 100% certainty which patients will go on to develop lymphedema and which will not. Patient-specific anatomic and physiologic differences may be the missing factor. The authors hypothesize that patients with accessory lymphatic pathways may have improved lymphatic drainage, resulting in smaller limb volumes.

METHODS

The authors reviewed indocyanine green (ICG) lymphography images of all patients who presented to their institution for evaluation of breast cancer-related lymphedema. Patients with unilateral upper extremity lymphedema, a full set of bilateral limb measurements, and ICG images of both limbs were included. Other variables of interest included patient demographics and length of follow-up. Patients with accessory pathways were determined independently, and conflicts were resolved with discussion. Abnormal images were also evaluated for common drainage pathways.

RESULTS

Thirty patients were identified as having accessory lymphatic drainage pathways. These patients had significantly smaller limb volume differences [8.19% (SD, 11.22)] compared with patients who did not exhibit these pathways [20.74% (SD, 19.76); P < 0.001]. The most common pathway was absence or rerouting of the radial bundle to the ulnar or volar bundles ( n = 16).

CONCLUSIONS

The ability to create accessory lymphatic drainage pathways may be associated with improved lymphatic drainage, resulting in smaller limb volumes. Furthermore, certain drainage pathways appear to be more common than others. Description of these pathways should be considered for inclusion in ICG lymphography image grading criteria. Further study is needed to clarify the nature of these pathways and whether these pathways affect subjective symptoms and quality of life.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.

Mapping the lymphatic system across body scales and expertise domains: A report from the 2021 National Heart, Lung, and Blood Institute workshop at the Boston Lymphatic Symposium

Enhancing our understanding of lymphatic anatomy from the microscopic to the anatomical scale is essential to discern how the structure and function of the lymphatic system interacts with different tissues and organs within the body and contributes to health and disease. The knowledge of molecular aspects of the lymphatic network is fundamental to understand the mechanisms of disease progression and prevention. Recent advances in mapping components of the lymphatic system using state of the art single cell technologies, the identification of novel biomarkers, new clinical imaging efforts, and computational tools which attempt to identify connections between these diverse technologies hold the potential to catalyze new strategies to address lymphatic diseases such as lymphedema and lipedema. This manuscript summarizes current knowledge of the lymphatic system and identifies prevailing challenges and opportunities to advance the field of lymphatic research as discussed by the experts in the workshop.

Superficial and functional imaging of the tricipital lymphatic pathway: a modern reintroduction

PURPOSE

The tricipital, or Caplan's, lymphatic pathway has been previously identified in cadavers and described as a potential compensatory pathway for lymphatic drainage of the upper extremity, as it may drain lymphatic fluid directly to the scapular lymph nodes, avoiding the axillary lymph node groups. The aim of this study was to map the anatomy of the tricipital pathway in vivo in patients without lymphatic disease.

METHODS

A retrospective review was performed to identify patients with unilateral breast cancer undergoing preoperative Indocyanine green (ICG) lymphography prior to axillary lymph node dissection from May 2021 through January 2022. Exclusion criteria were evidence or known history of upper extremity lymphedema or non-linear channels visualized on ICG. Demographic, oncologic, and ICG imaging data were extracted from a Lymphatic Surgery Database. The primary outcome of this study was the presence and absence of the tricipital pathway. The secondary outcome was major anatomical variations among those with a tricipital pathway.

RESULTS

Thirty patients underwent preoperative ICG lymphography in the study period. The tricipital pathway was visualized in the posterior upper arm in 90% of patients. In 63% of patients, the pathway had a functional connection to the forearm (long bundle variant) and in 27%, the pathway was isolated to the upper arm without a connection to the forearm (short bundle variant). In those with a long bundle, the contribution was predominantly from the posterior ulnar lymphosome. Anatomic destinations of the tricipital pathway included the deltotricipital groove and the medial upper arm channel, which drains to the axilla.

CONCLUSION

When present, the tricipital pathway coursed along the posterior upper arm with variability in its connections to the forearm distally, and the torso proximally. Long-term follow-up studies will help determine the significance of these anatomic variations in terms of individual risk of lymphedema after axillary nodal dissection.

Superficial and Functional Lymphatic Anatomy of the Upper Extremity

BACKGROUND

Knowledge of detailed lymphatic anatomy in humans is limited, as the small size of lymphatic channels makes it difficult to image. Most current knowledge of the superficial lymphatic system has been obtained from cadaveric dissections.

METHODS

Indocyanine green lymphography was performed preoperatively to map the functional arm lymphatics in breast cancer patients without clinical or objective evidence of lymphedema. A retrospective review was performed to extract demographic, indocyanine green imaging, and surgical data.

RESULTS

Three main functional forearm channels with variable connections to two upper arm pathways were identified. The median forearm channel predominantly courses in the volar forearm (99 percent). The ulnar forearm channel courses in the volar forearm in the majority of patients (66 percent). The radial forearm channel courses in the dorsal forearm in the majority of patients (92 percent). Median (100 percent), radial (91 percent), and ulnar (96 percent) channels almost universally connect to the medial upper arm channel. In contrast, connections to the lateral upper arm channel occur less frequently from the radial (40 percent) and ulnar (31 percent) channels.

CONCLUSIONS

This study details the anatomy of three forearm lymphatic channels and their connections to the upper arm in living adults without lymphatic disease. Knowledge of these pathways and variations is relevant to any individual performing procedures on the upper extremities, as injury to the superficial lymphatic system can predispose patients to the development of lymphedema.

Fluorescent Tracers for In Vivo Imaging of Lymphatic Targets

The lymphatic system continues to gain importance in a range of conditions, and therefore, imaging of lymphatic vessels is becoming more widespread for research, diagnosis, and treatment. Fluorescent lymphatic imaging offers advantages over other methods in that it is affordable, has higher resolution, and does not require radiation exposure. However, because the lymphatic system is a one-way drainage system, the successful delivery of fluorescent tracers to lymphatic vessels represents a unique challenge. Each fluorescent tracer used for lymphatic imaging has distinct characteristics, including size, shape, charge, weight, conjugates, excitation/emission wavelength, stability, and quantum yield. These characteristics in combination with the properties of the target tissue affect the uptake of the dye into lymphatic vessels and the fluorescence quality. Here, we review the characteristics of visible wavelength and near-infrared fluorescent tracers used for in vivo lymphatic imaging and describe the various techniques used to specifically target them to lymphatic vessels for high-quality lymphatic imaging in both clinical and pre-clinical applications. We also discuss potential areas of future research to improve the lymphatic fluorescent tracer design.

Reverse Lymphatic Mapping and Immediate Microsurgical Lymphatic Reconstruction Reduces Early Risk of Breast Cancer-Related Lymphedema

BACKGROUND

Breast cancer-related lymphedema is a progressive disease that poses tremendous physical, psychosocial, and financial burden on patients. Immediate lymphaticovenular anastomosis at the time of axillary lymph node dissection is emerging as a potential therapeutic paradigm to decrease the incidence of breast cancer-related lymphedema in high-risk patients.

METHODS

Eighty-one consecutive patients underwent reverse lymphatic mapping and, when feasible, supermicrosurgical immediate lymphaticovenular anastomosis at the time of axillary lymph node dissection at a tertiary care cancer center. Patients were followed prospectively in a multidisciplinary lymphedema clinic (plastic surgery, certified lymphatic therapy, dietary, case management) at 3-month intervals with clinical examination, circumferential limb girth measurements, and bioimpedance spectroscopy. An institutional control cohort was assessed for the presence of objectively diagnosed and treated breast cancer-related lymphedema. Data were analyzed by a university statistician.

RESULTS

Seventy-eight patients met inclusion, and 66 underwent immediate lymphaticovenular anastomosis. Mean follow-up was 250 days. When compared to a retrospective control group, the rate of lymphedema in patients who underwent immediate lymphaticovenular anastomosis was significantly lower (6 percent versus 44 percent; p < 0.0001). Patients with 6-month follow-up treated with combined adjuvant radiation therapy and chemotherapy had significantly greater risk of developing breast cancer-related lymphedema (p = 0.04) compared to those without combined adjuvant therapy. Arborized anastomotic technique had a statistically shorter operative time than end-to-end anastomosis (p = 0.005).

CONCLUSIONS

This series of consecutive patients demonstrate a 6 percent incidence of early-onset breast cancer-related lymphedema with immediate lymphaticovenular anastomosis and an increased risk in those undergoing combined adjuvant treatment. These early data represent an encouraging and substantial decrease of breast cancer-related lymphedema in high-risk patients.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Immediate Lymphatic Reconstruction for Prevention of Secondary Lymphedema: A Meta-Analysis

BACKGROUND

Secondary lymphedema remains one of the most notorious complications of axillary and pelvic lymph node surgery following mastectomy. There is a lack of high-level evidence found on the effectiveness of immediate lymphatic reconstruction (ILR) in preventing secondary lymphedema. This meta-analysis evaluates the outcomes of ILR for prevention of secondary lymphedema in patients undergoing different surgeries, and provides suggestions for lymphatic microsurgical preventive healing approach (LYMPHA).

METHODS

A review of PubMed, Embase, and Web of Science was performed according to Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. All English-language studies published from January 1, 2009 to June 1, 2020 were included. We excluded non-ILR interventions, literature reviews/letters/commentaries, and nonhuman or cadaver studies. A total of 789 patients that were enrolled in 13 studies were included in our one-arm meta-analysis.

RESULTS

A total of 13 studies (n=789) met inclusion criteria: upper extremity ILR (n=665) and lower extremity ILR (n=124). The overall incidence of lymphedema for upper extremity ILR was 2.7% (95%CI: 1.1%-4.4%) and lower extremity ILR was 3.6% (95%CI: 0.3%-10.1%). For upper extremity ILR, the average follow-up time was 11.6 ± 7.8 months and the LE incidence appeared to be the highest approximately 1 to 2 years postoperation.

CONCLUSIONS

Lymphedema is a common complication in cancer treatment. ILR, especially LYMPHA, may be an effective technique to facilitate lymphatic drainage at the time of the index procedure but future studies will be required to show its short-term efficacy and long-term outcomes.

Comparison of upper extremity lymphedema after sentinel lymph node biopsy and axillary lymph node dissection: patient-reported outcomes in 3044 patients

PURPOSE

A limited number of studies have examined the impact of type of axillary lymph node surgery on breast cancer-related lymphedema (BCRL) from the patient's perspective. The objective of this study was to assess the impact of sentinel lymph node dissection (SLND) and axillary lymph node dissection (ALND) on the health-related quality of life (HRQOL) in women diagnosed with BCRL using a condition specific patient-reported outcome measure (PROM), the LYMPH-Q upper extremity (UE) module.

METHODS

Adult women diagnosed with BCRL were identified from the Danish National Health Data Authority database for the period 2008 to 2020 and were sent an online REDCap survey with the LYMPH-Q UE module. Information pertaining to axillary surgery was obtained from an online pathology repository. Multivariable linear regression was used to examine differences in the SLND and ALND groups on the LYMPH-Q UE scale scores.

RESULTS

Three thousand and fourty four women with BCRL were included in the analysis. The mean follow-up duration was 8.6 ± 5.15 years (range, 0-36 years). The majority of participants underwent ALND (n = 2805, 92.1%) and only 7.9% (n = 239) received SLND. The mean number of lymph nodes removed in the SLND group was 2.2 ± 1.4. No statistically significant difference was found in the two groups on the LYMPH-Q UE scale scores.

CONCLUSION

There is no difference in women with upper extremity lymphedema after SLND or ALND on the LYMPH-Q UE module scales measuring arm symptoms, function, distress, and appearance.

Immediate Lymphatic Reconstruction: Technical Points and Literature Review

Recent studies have provided evidence that lymphovenous bypass—microsurgical re-routing of divided lymphatics to an adjacent vein—performed at the time of lymph node dissection decreases the rate of lymphedema development. Immediate lymphatic reconstruction in this setting is technically demanding, and there is a paucity of literature describing the details of the surgical procedure. In this report, we review the literature supporting immediate lymphatic reconstruction and provide technical details to demystify the operation for surgeons who wish to provide this option to their patients.

Breast Cancer-Related Lymphedema: Magnetic Resonance Imaging Evidence of Sparing Centered Along the Cephalic Vein

BACKGROUND

 A distinct pattern of edema distribution is seen in breast cancer-related lymphedema. The area of edema sparing has not been characterized in relation to anatomy. Specifically, alternate lymphatic pathways are known to travel adjacent to the cephalic vein. Our study aims to define the location of edema sparing in the arm relative to the cephalic vein.

METHODS

 A retrospective review of patients who underwent magnetic resonance imaging (MRI) between March 2017 and September 2018 was performed. Variables including patient demographics, arm volumes, and MRI data were extracted. MRIs were reviewed to define the amount of sparing, or angle of sparing, and the deviation between the center of sparing and the cephalic vein, or angle of deviation.

RESULTS

 A total of 34 consecutive patients were included in the analysis. Five patients demonstrated circumferential edema (no sparing) and 29 patients demonstrated areas of edema sparing. Advanced age (69.7 vs. 57.6 years) and greater excess arm volume (40.4 vs. 20.8%) correlated with having circumferential edema without sparing (p = 0.003). In 29 patients with areas of edema sparing, the upper arm demonstrated the greatest angle of sparing (183.2 degrees) and the narrowest in the forearm (99.9 degrees; p = 0.0032). The mean angle of deviation to the cephalic vein measured 3.2, -0.1, and -5.2 degrees at the upper arm, elbow, and forearm, respectively.

CONCLUSION

 Our study found that the area of edema sparing, when present, is centered around the cephalic vein. This may be explained by the presence of the Mascagni-Sappey (M-S) pathway as it is located alongside the cephalic vein. Our findings represent a key springboard for additional research to better elucidate any trends between the presence of the M-S pathway, areas of sparing, and severity of lymphedema.

Anatomical Theories of the Pathophysiology of Cancer-Related Lymphoedema

Lymphoedema is a well-known concern for cancer survivors. A crucial issue in lymphoedema is that we cannot predict who will be affected, and onset can occur many years after initial cancer treatment. The variability of time between cancer treatment and lymphoedema onset is an unexplained mystery. Retrospective cohort studies have investigated the risk factors for lymphoedema development, with extensive surgery and the combination of radiation and surgery identified as common high-risk factors. However, these studies could not predict lymphoedema risk in each individual patient in the early stages, nor could they explain the timing of onset. The study of anatomy is one promising tool to help shed light on the pathophysiology of lymphoedema. While the lymphatic system is the area least investigated in the field of anatomical science, some studies have described anatomical changes in the lymphatic system after lymph node dissection. Clinical imaging studies in lymphangiography, lymphoscintigraphy and indocyanine green (ICG) fluorescent lymphography have reported post-operative anatomical changes in the lymphatic system, including dermal backflow, lymphangiogenesis and creation of alternative pathways via the deep and torso lymphatics, demonstrating that such dynamic anatomical changes contribute to the maintenance of lymphatic drainage pathways. This article presents a descriptive review of the anatomical and imaging studies of the lymphatic system in the normal and post-operative conditions and attempts to answer the questions of why some people develop lymphoedema after cancer and some do not, and what causes the variability in lymphoedema onset timing.

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.