Staged surgical treatment of extremity lymphedema with dual gastroepiploic vascularized lymph node transfers followed by suction-assisted lipectomy-A prospective study

Comparing Different Donor Sites After Vascularized Lymph Node Transfer to the Lymphedematous Upper Limb: A Systematic Review and Meta-analysis of Clinical Outcomes

BACKGROUND

Vascularized lymph node transfer (VLNT) involves the microvascular transplantation of functional lymph nodes from a donor site into a limb affected by lymphedema to restore the normal flow of lymphatic fluid. Despite the increasing clinical experience with VLNT, there remains insufficient data to support its routine use in clinical practice. Here, we aim to evaluate the effectiveness and safety of VLNTs for upper limb lymphedema and compare clinical outcomes when using different donor sites.

METHODS

We carried out a systematic search of the literature through PubMed and Scopus databases for studies on VLNT for upper limb lymphedema. Primary and secondary outcomes included circumference reduction rate (CRR) and infection reduction rate by postoperative cellulitis episodes for the efficacy and safety of VLNT. Pooled analysis was performed using the inverse variance weighting meta-analysis of single means using the meta package in R software. Subgroup analyses were performed for donor and recipient sites, age groups, follow-ups, and symptom durations. Quality assessment was performed using the Newcastle-Ottawa Scale for nonrandomized studies.

RESULTS

A total of 1089 studies were retrieved from the literature, and 15 studies with 448 upper limb lymphedema patients who underwent VLNT were included after eligibility assessment. The mean CRR was 34.6 (18.8) and the mean postoperative cellulitis episodes per year was 0.71 (0.7). The pooled analysis of CRR was 28.4% (95% confidence interval, 19.7-41.1) and postoperative cellulitis episodes showed a mean of 0.59 (95% confidence interval, 0.36-0.95) using the random-effect model. Subgroup analyses showed significant group differences in recipient site for CRR and postoperative cellulitis episodes with the wrist comprising the highest weights, and patients younger than 50 years showing a lower postoperative infection.

CONCLUSIONS

Vascularized lymph node transfer using gastroepiploic flaps at the wrists has shown a significant difference in reductions of limb circumference and cellulitis episodes in upper limb lymphedema patients when compared with other donor sites. However, further prospective studies are needed to consolidate this finding.

Synchronous supraclavicular vascularized lymph node transfer and liposuction for gynecological cancer-related lower extremity lymphedema: a clinical comparative analysis of three different procedures

OBJECTIVE

Gynecological cancer-related lower extremity lymphedema (GC-LEL), a chronic, progressive condition, lacks a standardized treatment. Currently, supraclavicular vascularized lymph node transfer (SC-VLNT) is a favored approach in the treatment of lymphedema, and there is a trend toward combination technology. This study conducts a comparative analysis of three techniques for treating GC-LEL with simultaneous SC-VLNT and liposuction.

METHODS

A cohort of 35 patients with GC-LEL was examined, comprising 13 patients who underwent single lymph nodes flap with a skin paddle (SLNF+P), 12 who received single lymph nodes flap without a skin paddle (SLNF), and 10 who accepted dual lymph nodes flap without a skin paddle (DLNF). Patient demographics and outcomes were meticulously documented, covering intra- and postoperative variables.

RESULTS

The median limb volume reduction were 56.4% (SLNF+P), 60.8% (SLNF), and 50.5% (DLNF) in stage II, and 54.0% (SLNF+P), 59.8% (SLNF), and 54.4% (DLNF) in stage III. DLNF group procedures entailed longer flap harvesting and transplantation times. The SLNF+P group, on average, had an 8-day postoperative hospitalization, longer than others. All patients noted subjective improvements in Lymphedema Quality of Life scores, with lymphoscintigraphy revealing enhanced lymphatic flow in 29 of the 35 cases. A notable decrease in cellulitis incidence was observed. Additionally, the occurrence of cellulitis decreased significantly, except for DLNF (Stage Ⅱ). The median follow-up time was 16 months (range, 12-36 months), with no reported severe postoperative complications.

CONCLUSIONS

For advanced GC-LEL, SLNF combined with liposuction is a preferred treatment, offering fewer complications, shorter operative time, and hospitalization.

Commercial Insurance Rates and Coding for Lymphedema Procedures: The Current State of Confusion and Need for Consensus

BACKGROUND

Surgical treatment of lymphedema has outpaced coding paradigms. In the setting of ambiguity regarding coding for physiologic procedures [lymphovenous bypass (LVB) and vascularized lymph node transplant (VLNT)], we hypothesized that there would be variation in commercial reimbursement based on coding pattern.

METHODS

The authors performed a cross-sectional analysis of 2021 nationwide hospital pricing data for 21 CPT codes encompassing excisional (direct excision, liposuction), physiologic (LVB, VLNT), and ancillary (lymphangiography) procedures. Within-hospital ratios (WHRs) and across-hospital ratios (AHRs) for adjusted commercial rates per CPT code quantified price variation. Mixed effects linear regression modeled associations of commercial rate with public payer (Medicare and Medicaid), self-pay, and chargemaster rates.

RESULTS

A total of 270,254 commercial rates, including 95,774 rates for physiologic procedures, were extracted from 2863 hospitals. Lymphangiography codes varied most in commercial price (WHR, 1.76 to 3.89; AHR, 8.12 to 44.38). For physiologic codes, WHRs ranged from 1.01 (VLNT; free omental flap) to 3.03 (LVB; unlisted lymphatic procedure), and AHRs ranged from 5.23 (LVB; lymphatic channel incision) to 10.36 (LVB; unlisted lymphatic procedure). Median adjusted commercial rates for excisional procedures ($3635.84) were higher than for physiologic procedures ($2560.40; P < 0.001). Commercial rate positively correlated with Medicare rate for all physiologic codes combined, although regression coefficients varied by code.

CONCLUSIONS

Commercial payer-negotiated rates for physiologic procedures were highly variable both within and across hospitals, reflective of variation in CPT codes. Physiologic procedures may be undervalued relative to excisional procedures. Consistent coding nomenclature should be developed for physiologic and ancillary procedures.

Giant Penoscrotal Lymphedema-What to Do? Presentation of a Curative Treatment Algorithm

BACKGROUND

While rare, penoscrotal lymphedema (PL) is accompanied with devastating effects on the quality of life of patients. Moreover, especially for patients with excessive (giant) PL, no standardized curative treatment has been defined. This article therefore retrospectively evaluates the authors' surgical treatment approach for giant PL, which includes resection alone or in combination with a free vascularized lymph node transfer (VLNT).

METHODS

A total of ten patients met the inclusion criteria. One patient dropped out of the study before therapy commenced. Eight of the nine remaining patients presented with end-stage (giant) PL. One patient presented with manifest pitting edema. All patients were treated with penoscrotal resection and reconstruction. Additionally, five patients received VLNT into the groin or scrotum.

RESULTS

The extent of the lymphedema was specified with a treatment-oriented classification system. The median follow-up was 49.0 months. No patient showed a recurrence. Patients who received VLNT into the scrotum displayed a significantly improved lymphatic transport of the scrotum.

CONCLUSIONS

Advanced PL should be treated in a standardized surgical fashion as suggested by our proposed algorithm. VLNT from the lateral thoracic region into the scrotum must be considered. If treated correctly, surgical intervention of end-stage PL leads to good results with a low recurrence rate.

Outcomes after microsurgical treatment of lymphedema: a systematic review and meta-analysis

BACKGROUND

Microsurgical treatment options for lymphedema consist mainly of lymphovenous anastomosis (LVA) and vascularized lymph node transfers (VLNTs). There are no standard measurements of the effectiveness of these interventions and reported outcomes vary among studies.

METHODS

A systematic review and meta-analysis were performed based on a structured search in Embase, Medline, PubMed, Cinahl, Cochrane, and ProQuest in October 2020, with an update in February 2022. Firstly, a qualitative summary of the main reported outcomes was performed, followed by a pooled meta-analysis of the three most frequently reported outcomes using a random effects model. Randomized controlled trials, prospective cohorts, retrospective cohorts, and cross-sectional and case-control studies that documented outcomes following microsurgery in adult patients were included. Studies of other surgical treatments (liposuction, radical excision, lymphatic vessel transplantation) or without reported outcomes were excluded. The study protocol was registered on PROSPERO (International Prospective Register of Systematic Reviews) (ID: CRD42020202417). No external funding was received for this review.

RESULTS

One hundred fifty studies, including 6496 patients, were included in the systematic review. The qualitative analysis highlighted the three most frequently reported outcomes: change in circumference, change in volume, and change in the number of infectious episodes per year. The overall pooled change in excess circumference across 29 studies, including 1002 patients, was -35.6% [95% CI: -30.8 to -40.3]. The overall pooled change in excess volume across 12 studies including 587 patients was -32.7% [95% CI: -19.8 to -45.6], and the overall pooled change in the number of cutaneous infections episodes per year across 8 studies including 248 patients was -1.9 [95% CI: -1.4 to -2.3]. The vast majority of the studies included were case series and cohorts, which were intrinsically exposed to a risk of selection bias.

CONCLUSION

The currently available evidence supports LVA and vascularized lymph node transfers as effective treatments to reduce the severity of secondary lymphedema. Standardization of staging method, outcomes measurements, and reporting is paramount in future research in order to allow comparability across studies and pooling of results.

Technical details for inset of flaps in transfer of double-level gastroepiploic lymph node flaps for lower extremity lymphedema

BACKGROUND

In this study, the method that can be followed to ensure rapid and uncomplicated recovery of lymph node flap (LNF) applied in the medial of the ankle for lymphedema treatment was investigated.

METHODS

Thirty-seven patients with class II of lower limb lymphedema underwent transfer of gastroepiploic LNF to the medial ankle and popliteal fossa areas. At the popliteal fossa region, the wound could always be closed primarily by the advancement of neighboring skin. The wound closure could be classified into three types at the medial ankle area (A) The partially exposed LNF was covered with a split-thickness skin graft (STSG) (n = 9). (B) A larger local flap was elevated, and the donor site of the local flap was covered with STSG (n = 18). (C) The skin flap's donor site was treated with pre-tie sutures (n = 10).

RESULTS

In the popliteal region, there was no complication of wound healing. In the ankle region, the wound was coated by a thin layer of hematoma over the exposed LNF in 5 patients of group A. It healed secondarily except for one patient who needed a secondary skin graft. The healing was perfect in group B. In group C the healing was good, but there was a hypertrophic scar in 7 patients and required steroid injection later.

CONCLUSION

To avoid complications of the gastroepiploic LNF at the medial ankle, it should be entirely covered by an anteriorly-based local flap, and the donor site defect of the local flap can be treated with either pre-tie sutures or a skin graft.

Overview of Lymphedema for Physicians and Other Clinicians: A Review of Fundamental Concepts

Lymphedema has historically been underrated in clinical practice, education, and scholarship to the detriment of many patients with this chronic, debilitating condition. The mechanical insufficiency of the lymphatic system causes the abnormal accumulation of protein-rich fluid in the interstitium, which triggers a cascade of adverse consequences such as fat deposition and fibrosis. As the condition progresses, patients present with extremity heaviness, itchiness, skin infections, and, in later stages, dermal fibrosis, skin papillomas, acanthosis, and other trophic skin changes. Correspondingly, lymphedema results in psychological morbidity, including anxiety, depression, social avoidance, and a decreased quality of life, encompassing emotional, functional, physical, and social domains. For this review, we conducted a literature search using PubMed and EMBASE and herein summarize the evidence related to the fundamental concepts of lymphedema. This article aims to raise awareness of this serious condition and outline and review the fundamental concepts of lymphedema.

A Prospective Study on the Safety and Efficacy of Vascularized Lymph Node Transplant

PURPOSE

While vascularized lymph node transplant (VLNT) has gained popularity, there are a lack of prospective long-term studies and standardized outcomes. The purpose of this study was to evaluate the safety and efficacy of VLNT using all available outcome measures.

METHODS

This was a prospective study on all consecutive patients who underwent VLNT. Outcomes were assessed with 2 patient-reported outcome metrics, limb volume, bioimpedance, need for compression, and incidence of cellulitis.

RESULTS

There were 89 patients with the following donor sites: omentum (73%), axilla (13%), supraclavicular (7%), groin (3.5%). The mean follow-up was 23.7±12 months. There was a significant improvement at 2 years postoperatively across all outcome measures: 28.4% improvement in the Lymphedema Life Impact Scale, 20% average reduction in limb volume, 27.5% improvement in bioimpedance score, 93% reduction in cellulitis, and 34% of patients no longer required compression. Complications were transient and low without any donor site lymphedema.

CONCLUSIONS

VLNT is a safe and effective treatment for lymphedema with significant benefits fully manifesting at 2 years postoperatively. Omentum does not have any donor site lymphedema risk making it an attractive first choice.

Updates on Excisional Procedures for Lymphedema

Significance: Excisional procedures for lymphedema have been used for over a century, and many surgeons have abandoned the old techniques as improvements in nonsurgical management and microsurgery have limited their clinical utility. Nonetheless, excisional procedures remain relevant as an important tool in the comprehensive surgical management of lymphedema. Recent Advances: Modifications to the Charles procedure and other direct excisional procedures have improved the complication profile and patient outcomes. Moreover, the use of liposuction techniques for minimally invasive tissue excision has expanded the scope of excisional surgery to benefit patients with less severe lymphedema. Recent operations combining excisional and physiologic procedures may prove to have superior results to stand-alone procedures. Critical Issues: No standard protocol exists for the comprehensive surgical management of lymphedema. Proper patient selection for any procedure requires robust outpatient assessment, cooperation with physiotherapy treatment teams, careful patient stratification, and a clear understanding of the procedure's goal. Future Directions: Larger, prospective trials will be needed to elucidate the ideal timing and combinations of techniques to optimize outcomes for patients with late-stage lymphedema.

Lessons Learnt from an 11-year Experience with Lymphatic Surgery and a Systematic Review of Reported Complications: Technical Considerations to Reduce Morbidity

Complications experienced during lymphatic surgery have not been ubiquitously reported, and little has been described regarding how to prevent them. We present a review of complications reported during the surgical management of lymphedema and our experience with technical considerations to reduce morbidity from lymphatic surgery. A comprehensive search across different databases was conducted through November 2020. Based on the complications identified, we discussed the best approach for reducing the incidence of complications during lymphatic surgery based on our experience. The most common complications reported following lymphovenous anastomosis were re-exploration of the anastomosis, venous reflux, and surgical site infection. The most common complications using groin vascularized lymph node transfer (VLNT), submental VLNT, lateral thoracic VLNT, and supraclavicular VLNT included delayed wound healing, seroma and hematoma formation, lymphatic fluid leakage, iatrogenic lymphedema, soft-tissue infection, venous congestion, marginal nerve pseudoparalysis, and partial flap loss. Regarding intra-abdominal lymph node flaps, incisional hernia, hematoma, lymphatic fluid leakage, and postoperative ileus were commonly reported. Following suction-assisted lipectomy, significant blood loss and transient paresthesia were frequently reported. The reported complications of excisional procedures included soft-tissue infections, seroma and hematoma formation, skin-graft loss, significant blood loss, and minor skin flap necrosis. Evidently, lymphedema continues to represent a challenging condition; however, thorough patient selection, compliance with physiotherapy, and an experienced surgeon with adequate understanding of the lymphatic system can help maximize the safety of lymphatic surgery.

Indocyanine green-guided liposuction for patients presenting with residual nonpitting edema after lymphovenous anastomosis

INTRODUCTION

Lymphovenous anastomoses (LVA) techniques for the treatment of lymphedema are well defined, and results restoring lymph function are reported in the literature. However, unsatisfactory results (poor-responders) are common, leading to persistent nonpitting edema. Blind liposuction eliminates fat and fibrous tissue but may result in inadvertent damage to the lymph vessel system. Indocyanine green imaging of the lymphatic system provides the potential preservation of functioning lymphatics while conducting liposuction to address the excess adipose and fibrous tissue in these patients. Our study reports the results of a prospectively conducted technique in patients with nonpitting edema after failing previous LVA. It consists of indocyanine green-guided liposuction.

PATIENTS AND METHOD

Twenty poor-responders patients to LVA who presented with persistent nonpitting edema were operated with liposuction. Limb volume measurements, SPECT-CT/lymphoscintigraphy, and ICG lymphography were recorded and complemented with a satisfaction inquiry.

RESULTS

The overall percentage of volume reduction was 46.2% after liposuction (p = 0.001). None of our patients reported any set back with respect to the improvements they had achieved after LVA nor new infections. Satisfaction showed a mean improvement of 5 points in a 20-point scale. SPECT-CT/lymphoscintigraphy showed further improvements in 17 cases after liposuction, such as dermal back-flow reduction, spots along the lymphatic system, or lymph nodes not described in preoperative reports, without showing significant differences when compared with overall volume reduction (p = 0.12).

CONCLUSION

Controlled liposuction with ICG seems to be an effective technique for the reduction of residual non-pitting edema in poor responder patients after LVA. Overall, volume excess reduction after liposuction was 42.6%.

Multimodality Approach to Lymphedema Surgery Achieves and Maintains Normal Limb Volumes: A Treatment Algorithm to Optimize Outcomes

Surgical treatment of advanced lymphedema is challenging and outcomes are suboptimal. Physiologic procedures including lymphaticovenous anastomosis (LVA) and vascularized lymph node transfer (VLNT) improve lymphatic flow but cannot reverse fibrofatty tissue deposition, whereas liposuction removes fibrofatty tissue but cannot prevent disease progression. The adjunctive use of nanofibrillar collagen scaffolds (BioBridge^TM) can promote lymphangiogenesis. We report a treatment algorithm utilizing a multimodality approach to achieve sustained normal limb volumes in patients with stage II-III lymphedema. A retrospective review of late stage II-III lymphedema patients treated with liposuction, physiologic procedures, and BioBridge^TM from 2016 through 2019 was conducted. Treatment outcome in the form of excess volume reduction is reported. Total of 14 patients underwent surgical treatment of late stage II and III lymphedema according to our triple therapy algorithm. Patients had a baseline median volume excess of 29% (19.8, 43.3%). The median volume excess was improved to 0.5% (−4.3, 3.8%) at 14.4 months from the first stage surgery (p < 0.05) and further improved to −1.0% (−3.3, 1.3%) after triple therapy with BB placement at 24.6 months. A triple therapy surgical treatment algorithm can optimize outcomes and achieve sustained normalization of limb volume in late stage II-III lymphedema. The incorporation of nanofibrillar collagen scaffold technology allows for improved and sustained volume reduction.

The Combination of Lymph Node Transfer and Excisional Procedures in Bilateral Lower Extremity Lymphedema: Clinical Outcomes and Quality of Life Assessment with Long-Term Follow-Up

Background: Bilateral lower extremity lymphedema is a rare and invalidating condition that poses a great challenge to the scientific community, and deeply affects the quality of life (QoL) of affected patients. A combined protocol consisting of lymph node transfer and a reductive method have never been reported for the treatment of this condition, except for small case series with brief follow-up periods. Methods: This retrospective study analyzed data of 29 patients, mean age 51 ± 17.1 years, who had been diagnosed with bilateral lower extremity lymphedema. Gastroepiploic vascularized lymph node transfer was performed in all the patients, and an excisional procedure was associated according to the clinical stage. Clinical history, circumferential limb measurements, complications, episodes of cellulitis, and responses to the Lymphedema Quality of Life Questionnaire were analyzed. Results: The mean follow-up was 38.4 ± 11.8 months. A significant reduction in the episodes of cellulitis per year was observed (p < 0.001). In our series, BMI and duration of symptoms were significantly related to the development of cellulitis during the postoperative period, p = 0.006 and p = 0.020, respectively. The LYMQoL questionnaire showed a significant quality of life improvement from 3.4 ± 0.9 to 6.2 ± 0.8 (p < 0.05). Conclusions: An integrated approach is essential for the treatment of bilateral lower extremity lymphedema: reductive and reconstructive methods are complementary to achieve a successful outcome. Timely treatment and BMI reduction are relevant in order to decrease the number of episodes of cellulitis. An attentive follow-up is necessary to identify recurrence and treat affected patients in time.

Combined lymph node transfer and suction-assisted lipectomy in lymphedema treatment: A prospective study

BACKGROUND

Recent studies have analyzed the combination of suction-assisted lipectomy (SAL) and vascularized lymph node transfer (VLNT) in lymphedema treatment, reporting positive outcomes. However, it is difficult to draw conclusions due to the heterogeneity of the studies. Aim of this prospective study is to evaluate the effectiveness of the combination of VLNT and SAL in lymphedema treatment.

PATIENTS AND METHODS

Between January 2016 and May 2019, 94 patients with upper or lower limb stage IIb-III lymphedema were enrolled and treated with the gastroepiploic VLNT followed by SAL. Patients were prospectively evaluated through circumference measurement and clinical examination, including number of episodes of cellulitis.

RESULTS

Among patients enrolled in the study 83 were affected by lower limb lymphedema (LLL) and 11 were affected by upper limb lymphedema (ULL). Average follow-up was 3 ± 0.8 years. In the LLL group, the mean circumference reduction rates (CRR) were 60.4, 56.9, 29.6, and 55.4% above and below the knee, above the ankle, and at the foot level, respectively. A statistically significant difference was noted at all the levels (p < .05), but above the ankle (p = .059). Regarding the ULL group, the mean CRR were 80.7, 60.7, 65.0 and 49.6% above and below the elbow, at wrist and at mid-hand, respectively. CRR were reported at all the levels but no statistical difference was noted. The number of episodes of cellulitis dropped significantly (p < .05).

CONCLUSION

This study supports the use of VLNT+SAL in lymphedema grades IIb-III, with important implications for the clinical practice.

Novel Wireless Bioimpedance Device for Segmental Lymphedema Analysis Post Dual-Site Free Vascularized Lymph Node Transfer: A Prospective Cohort Study

An innovative wireless device for bioimpedance analysis was developed for post-dual-site free vascularized lymph node transfer (VLNT) evaluation. Seven patients received dual-site free VLNT for unilateral upper or lower limb lymphedema. A total of 10 healthy college students were enrolled in the healthy control group. The device was applied to the affected and unaffected limbs to assess segmental alterations in bioimpedance. The affected proximal limb showed a significant increase in bioimpedance at postoperative sixth month (3.3 [2.8, 3.6], p = 0.001) with 10 kHz currents for better penetration, although the difference was not significant (3.3 [3.3, 3.8]) at 1 kHz. The bioimpedance of the affected distal limb significantly increased after dual-site free VLNT surgery, whether passing with the 1 kHz (1.6 [0.7, 3.4], p = 0.030, postoperative first month; 2.8 [1.0, 4.2], p = 0.027, postoperative third month; and 1.3 [1.3, 3.4], p = 0.009, postoperative sixth month) or 10 kHz current ((1.4 [0.5, 2.7], p = 0.049, postoperative first month; 3.2 [0.9, 6.3], p = 0.003, postoperative third month; and 3.6 [2.5, 4.1], p < 0.001, postoperative sixth month). Bioimpedance alterations on the affected distal limb were significantly correlated with follow-up time (rho = 0.456, p = 0.029 detected at 10 kHz). This bioimpedance wireless device could quantitatively monitor the interstitial fluid alterations, which is suitable for postoperative real-time surveillance.

Advances in surgical treatment of lymphedema

An estimated 250 million people worldwide suffer from lymphedema. In the past, the firstline option for treatment was nonsurgical management, either in the form of compression garments or wrapping, or comprehensive decongestive therapy, with debulking surgery reserved for the more advanced cases. However, with improvements in microsurgical techniques and imaging modalities, surgical intervention is increasingly being utilized. This review highlights recent advancements in the surgical treatment of lymphedema, specifically focusing on improvements in imaging, surgical techniques, and prevention of lymphedema.

Genital Lymphedema and How to Deal with It: Pearls and Pitfalls from over 38 Years of Experience with Unusual Lymphatic System Impairment

Background and Objectives: Conservative treatment represents an essential pillar of lymphedema management, along with debulking and physiologic surgeries. Despite the consistent number of treatment options, there is currently no agreement on their indications and possible combinations. When dealing with unusual lymphedema presentation as in the genitalia (Genital Lymphedema—GL), treatment choice becomes even more difficult. The authors aimed to present their targeted algorithm of single and combined treatment modalities for rare GL in order to face this paucity of information. Materials and Methods: Data were collected from a prospectively maintained database since January 1983, and cases of GL that were managed in the authors’ department were selected. Only patients that were treated in the authors’ institution and presented a minimum follow-up of 3 months were admitted to the current study. Results: From January 1983 to July 2021, 19 patients with GL were recruited. All the patients were male, and their ages ranged from 21 to 73 years old (average: 52). Ten cases (52.6%) presented with ISL (International Society of Lymphology) stage I, five (26.3%) were stage II and four (21.1%) were stage III. GL was managed with conservative treatment (12 cases), LVA (LymphaticoVenous Anastomosis) (3) or surgical excision (4). In a mean follow-up of 7.5 years (range: 3 months—11 years), no major complications occurred, and all cases reached improvements in functional and quality of life terms. Conclusions: Contrary to the predominant thought of the necessity to avoid surgery in unusual lymphedema presentations such as GL, they can be managed using targeted multimodal approaches or by adapting well-known procedures in unusual ways to achieve control of disease progression and improve patients’ quality of life.

The use of pedicled chimeric superficial circumflex iliac artery perforator (SCIP) flap as lymphatic interpositional flap for deep thigh defect reconstruction: A case report

The tumors affecting the thigh region are complex to manage, requiring a patient-tailored and multidisciplinary approach. Because of their aggressiveness, soft tissue sarcomas (STS) often grow very quickly and they must be removed before they might cause major impairments. A safe margin excision may lead to large defects that require a surgical reconstruction with either free or pedicled flaps. Another relevant aspect, which is gaining more and more attention in the last few years, regards the lymphatic complications that commonly occur after these procedures. The thigh region anatomically accommodates the major lymphatics responsible for the whole leg drainage, and these vessels are often inevitably compromised during the tumor removal. For this reason, plastic surgeons should take into account not only to the aesthetic and functional result, but they should also try to prevent lymphatic sequelae such as lymphocele and lymphedema. The purpose of this report is to describe the potential of a pedicled SCIP flap, used as a lymphatic interpositional flap, in order to restore the lymphatic drainage of the thigh after a major impairment. A 57-year-old patient presenting a thigh sarcoma received a surgical excision leaving a 35 cm × 25 cm defect affecting the anterior compartment. To fulfill all these concerns, a lymphatic interpositional SCIP flap was performed, in pedicled and chimeric fashion. It allowed to completely bury a large (35 cm × 16 cm) soft tissue island, preserving a smaller (5 cm × 4 cm) skin paddle to monitor the whole flap survival. Moreover, the lymphatic issue was faced by preserving the lymphatic vessels running into the flap and moving them into the affected area in order to enhance the lymphatic neo-angiogenesis and offering an additional pattern for lymph drainage. Post-operative course was uneventful and at 9 months follow up the reconstructive result was successful with no signs of lymphatic sequelae. Therefore, we believe that the SCIP flap might be a promising solution for small-to-moderate size thigh defect reconstructions since it is able to satisfy all the typical requirements of this delicate region.

Intra-abdominal vascularized lymph node transfer for treatment of lymphedema: A systematic literature review and meta-analysis

BACKGROUND

As a promising treatment for lymphedema, vascularized lymph node transfer (VLNT) is associated with a risk of iatrogenic lymphedema. Intra-abdominal vascularized lymph node flap has been increasingly applied to minimize complication.

METHODS

PubMed, EMBASE, Web of Sciences, and Cochrane databases were searched systematically. Clinical articles describing the application of intra-abdominal flaps to treat lymphedema were included. Study characteristics, patient demographics, and operative details were recorded. Primary outcomes were recorded as circumference/volume reduction, episodes of cellulitis reduction and lymph flow assessment. Secondary outcomes were recorded as donor-site complication and recipient-site complication.

RESULTS

Twenty-one studies met the inclusion criteria with 594 patients in total. Donor-sites of flaps were omental/gastroepiploic, jejunal, ileocecal, and appendicular. The mean reduction rate ranged from 0.38% to 70.8%. Significant reduction in infectious episodes was reported in 10 studies. The pooled donor-site complication rate was 1.4% (95% CI, 0%-4.1%; I²  = 40%). The pooled recipient-site complication rate was 3.2% (95% CI, 1.4%-5.5%; I²  = 39%). The most common donor-site complication was minor ileus requiring prolonged nasogastric tube replacement. No donor site lymph disfunction occurred.

CONCLUSION

Intra-abdominal VLNT is an effective technique for patients with lymphedema with no obvious impairment to donor-site lymph function, as long as the operation is properly performed.

Vascularized omental lymphatic transplant for upper extremity lymphedema: A systematic review

BACKGROUND

Vascularized omental lymphatic transplant (VOLT) is an increasingly popular treatment of extremity lymphedema given its promising donor site. While the success of VOLT in the treatment of lymphedema has been reported previously, several questions remain.

AIM

To further elucidate appropriate use of VOLT in the treatment of lymphedema, specifically addressing patient selection, harvest technique, and operative methods.

METHODS AND RESULTS

A systematic review of VOLT for upper extremity lymphedema was performed. Of 115 yield studies, seven were included for analysis based on inclusion and exclusion criteria. Included studies demonstrated significant reductions in extremity circumference/volume (average volume reduction, 22.7%-39.5%) as well as subjective improvements using patient-reported outcomes. Though studies are heterogenous and limited, when analyzed in aggregate, suggest the efficacy of VOLT in lymphedema treatment.

CONCLUSION

This is the largest systematic review of VOLT to date. VOLT continues to show promise as a safe and efficacious surgical intervention for lymphedema in the upper extremity. Further studies are warranted to more definitively identify patients for whom this technique is appropriate as well as ideal harvest and inset technique.

A meta-analysis of the efficacy of vascularised lymph node transfer in reducing limb volume and cellulitis episodes in patients with cancer treatment-related lymphoedema

BACKGROUND

Lymphoedema after cancer treatment is a chronic and disabling complication that presents a significant health care burden during survivorship with limited treatment options. Vascularised lymph node transfer (VLNT) can reconstruct lymphatic flow to reduce limb volumes, but limited higher-order evidence exists to support its effectiveness.

AIM

The aim of the study was to systematically review and meta-analyse the effectiveness of VLNT in reducing upper limb (UL) or lower limb (LL) volume and cellulitis episodes in patients with cancer treatment-related lymphoedema (CTRL).

METHODS

PubMed, Medline (Ovid) and Embase databases were searched between January 1974 and December 2019. Full-length articles where VLNT was the sole therapeutic procedure for CTRL, reporting volumetric limb, frequency of infection episodes and/or lymphoedema-specific quality-of-life data, were included in a random-effects meta-analysis of circumferential reduction rate (CRR). Methodological quality was assessed using STROBE/CONSORT, and a novel, lymphoedema-specific scoring tool was used to assess lymphoedema-specific methodological reporting. Sensitivity analyses on the site of VLNT harvest and recipient location were performed.

RESULTS

Thirty-one studies (581 patients) were eligible for inclusion. VLNT led to significant limb volume reductions in UL (above elbow pooled CRRs [CRR_P] = 42.7% [95% confidence interval (CI): 36.5-48.8]; below elbow CRR_P = 34.1% [95% CI: 33.0-35.1]) and LL (above knee CRR_P = 46.8% [95% CI: 43.2-50.4]; below knee CRR_P = 54.6% [95% CI: 39.0-70.2]) CTRL. VLNT flaps from extra-abdominal donor sites were associated with greater volume reductions (CRR_P = 49.5% [95% CI: 46.5-52.5]) than those from intra-abdominal donor sites (CRR_P = 39.6% [95% CI: 37.2-42.0]) and synchronous autologous breast reconstruction/VLNT flaps (CRR_P = 32.7% [95% CI: 11.1-54.4]) (p < 0.05). VLNT was also found to reduce the mean number of cellulitis episodes by 2.1 episodes per year (95% CI: -2.7- -1.4) and increased lymphoedema-specific quality-of-life scores (mean difference in Lymphoedema-Specific Quality of Life (LYMQOL) "overall domain" = +4.26).

CONCLUSIONS

VLNT is effective in reducing excess limb volume and cellulitis episodes in both UL and LL lymphoedema after cancer treatment. However, significant heterogeneity exists in outcome reporting, and standardisation of reporting processes is recommended.

Combined Liposuction and Physiologic Treatment Achieves Durable Limb Volume Normalization in Class II-III Lymphedema: A Treatment Algorithm to Optimize Outcomes

INTRODUCTION

Outcomes of surgical lymphedema treatment are currently suboptimal. Physiologic procedures including lymphovenous anastomosis (LVA) and vascularized lymph node transfer (VLNT) reestablish lymphatic flow but cannot correct fibroadipose deposition, whereas liposuction alone cannot prevent disease progression. We propose a treatment algorithm combining liposuction with LVA or VLNT that can achieve normal limb volumes and prevent disease progression in stage II-III lymphedema.

METHODS

We performed a retrospective chart review of patients undergoing liposuction and physiologic lymphedema operations at our institution between January 2016 and June 2019. Patients were assigned to treatment groups according to their clinical presentation: physiologic first, followed by no further treatment (physiologic only) or liposuction (physiologic then liposuction); liposuction then physiologic; or simultaneous. Preoperative patient characteristics and sequence of operations were recorded. Compression garment usage was self-reported. Limb volumes were approximated as a truncated cone.

RESULTS

Twenty-one patients met the inclusion criteria. The liposuction then physiologic group had significantly higher stage and excess limb volume at baseline, whereas the physiologic first groups had lower excess volume. While the physiologic only group had predominantly stage I disease, the patients who later required liposuction (physiologic then liposuction group) all had stage II disease. All groups achieved 82% to 106% mean excess volume reduction, and volume reduction was maintained for up to 2.4 years. Compression garment class was not reduced, but mean postoperative compression duration decreased from 12.5 to 7.5 h/d (P = 0.003). Ten of 11 patients with history of cellulitis had no further recurrence.

CONCLUSION

Lymphedema represents a continuum of fluid and fibroadipose disease. Accurate staging and timely treatment with physiologic procedures and liposuction can normalize limb volume. We propose a treatment algorithm to optimize outcomes. Patients with predominantly nonpitting presentation benefit from liposuction to maximize removal of fibroadipose tissue and optimize postoperative compression, followed by LVA or VLNT to improve lymphatic drainage. Patients with primarily pitting edema are best treated with physiologic procedures initially, reserving selective liposuction as a second stage. Patients with mixed presentation are best served by single-stage combination procedures.

The deep inferior epigastric lymphatic cable flap connected to gastroepiploic lymph node flap for treatment of refractory chylous ascites: Report of two cases

Chylous ascites is the leakage of lipid-rich lymph into the peritoneal cavity usually due to disruption of lymphatics or increased peritoneal lymphatic pressure. Various surgical options have been proposed to treat chylous ascites but most have shown suboptimal outcomes. The gastroepiploic vascularized lymph node (GE-VLN) flap has been described previously for the treatment of lymphedema. In chylous ascites, this flap could provide an alternate drainage pathway for the intraperitoneal chylous fluid. The purpose of this report is to present another option for the microsurgical treatment of refractory chylous ascites. Herein, we report two patients with refractory chylous ascites secondary to cancer who have undergone deep inferior epigastric-based lymphatic "cable" flap (DIE-LCF) connected to a pedicle GE-VLN flap. Patients were followed-up for a minimum of 2 years. Within the first 3 months following surgery, the patient's nutritional parameters improved along with drastic reduction of ascites. At 2 years follow-up postoperative abdominal circumference decreased significantly. None required further peritoneal paracentesis and all patients were free of chylous ascites symptoms. In conclusion, the DIE-LCF connected to a pedicle GE-VLN flap could be a feasible option for the microsurgical treatment of refractory chylous ascites.

Outcomes of Vascularized Lymph Node Transplantation for Treatment of Lymphedema

BACKGROUND

A growing body of evidence supports the efficacy of surgical treatments for lymphedema. This study reports the outcomes of vascularized lymph node transplantation (VLNT) for the treatment of patients with lymphedema compared with maximal conservative treatment alone.

STUDY DESIGN

Consecutive patients undergoing VLNT to treat primary and secondary lymphedema affecting the upper or lower extremities were included. All patients were optimized preoperatively with conservative therapy. Demographic and treatment information was collected, and outcomes data were electronically captured prospectively; descriptive statistics were performed.

RESULTS

There were 134 patients included that had achieved maximal reductions by conservative therapy preoperatively. This series included jejunal mesenteric (n = 25), groin (n = 43), lateral thoracic (n = 31), omental or right gastroepiploic (n = 21), and submental (n = 14) VLN flaps. At 24 months postoperatively, there were significant reductions in limb volume change (mean [SD] 45.7% [8.7%]; p = 0.002) LDex score (mean [SD] 59.8% [8.7%]; p < 0.001), Lymphedema Life Impact Scale score (mean [SD] 61.6% [5.9]; p < 0.001), and cellulitis episodes (97.9%; p < 0.001). At 3 and 6 months postoperatively, limb volume change was significantly greater for the upper than the lower extremity, otherwise outcomes were similar. There were no flap losses and overall outcomes were similar between the different VLN flap types.

CONCLUSIONS

Treatment of lymphedema using VLNT resulted in progressive, significant reductions in limb volume, bioimpedance spectroscopy measurements of extracellular fluid, and episodes of cellulitis, with improved patient-reported outcomes and limb function measures compared with maximal conservative therapy alone. The complication rate was low and there were no significant outcomes differences between the VLNT types.

Current operative management and therapeutic algorithm of lymphedema in the lower extremities

Lymphedema is defined as the abnormal accumulation of interstitial fluid in subcutaneous tissues resulting from cancer, cancer treatment (surgery and/or radiotherapy), infection, inflammatory disorders, obesity, and hereditary syndromes. Surgical management of lymphedema can be broadly classified into two categories, reductive surgical techniques such as direct excision, suction assisted protein lipectomy (SAPL) or radical reduction with perforator preservation (RRPP); and physiological surgical procedures such as lymphaticovenous anastomosis (LVA) and vascularised lymph node transfer (VLNT). These techniques and their various combinations were evaluated. The results revealed patients with reversible lymphedema (ISL stage I, mild severity) benefit most from physiological procedures (LVA or VLNT) which can reduce the chance of disease progression to the chronic, solid phase. Reductive techniques such as SAPL, RPPP, or direct excision procedures should be reserved for patients with advanced - severe lymphedema (ISL stages II and especially stage III) as the surgical treatment of choice. In this study, current literature on the surgical treatment of lower extremity lymphedema is reviewed and discussed in conjunction with authors' clinical experiences. An algorithm is presented, based on clinical evidence and experience which aims to provide a structured approach to managing lower limb lymphedema.

A prospective study on combined lymphedema surgery: Gastroepiploic vascularized lymph nodes transfer and lymphaticovenous anastomosis followed by suction lipectomy

BACKGROUND

There is no consensus on the appropriate treatment of lymphedema. Proposed techniques include lymphaticovenous anastomosis (LVA), vascularized lymph nodes transfer (VLNT), and suction lipectomy (SL). The benefit of combined procedures has also been postulated. In this prospective study, a combined protocol is proposed as an alternative to single-procedure strategies.

METHODS

Between January 2016 and October 2018, we enrolled patients with secondary lymphedema of lower limbs, stage II-III according to the International Society of Lymphology, progressive swelling and skin tonicity >60. Thirty-seven consecutive patients were dichotomized into group I, undergoing VLNT, and group II undergoing VLNT and LVA. Gastroepiploic lymphnode flap was harvested through laparoscopy, and in the same operation, LVAs were performed in group II on the basis of indocyanine green lymphography and patent blue findings. Two weeks later, SL was performed in all the patients. Patients were prospectively evaluated through clinical examination, circumference measurement, and skin tonicity.

RESULTS

The average follow-up was 2 ± 0.8 years. The first consecutive 21 patients were treated with VLNT followed by SL. The next 16 patients underwent combined VLNT and LVA, followed by SL. A mean of 2.4 LVAs were performed. A significant difference in the postoperative circumference measurements was found overall (p < .05): 52.6 ± 18.9 above the knee, 42.9 ± 25 below the knee, 36.2 ± 37 at foot. The postoperative tonicity dropped by 12.7 ± 6.3% (p < .05). The episodes of cellulitis significantly decreased to 0.1 ± 0.3 (p < .05).

CONCLUSIONS

LVA, VLNT, and SL can be integrated together in a combined approach, in synergy to enhance the outcomes.

Single-stage VASER-assisted liposuction and lymphatico-venous anastomoses for the treatment of extremity lymphedema: a case series and systematic review of the literature

Background

A paradigm shift towards the use of combined physiological and excisional surgical approaches for the treatment of lymphedema is permeating the surgical practice worldwide. We describe a single-stage surgical approach combining-vaser assisted liposuction (VAL) and lymphatico-venous anastomoses (LVA) for the treatment of extremity-lymphedema.

Methods

Between March 2018 and March 2019, a retrospective review of patients with extremity-lymphedema stage IIb-III International Society of Lymphology who underwent the combined technique was done. Demographics, operative characteristics, clinical outcomes and complications were assessed. Additionally, a systematic review of studies that reported combined physiological procedures with liposuction for the treatment of lymphedema was conducted.

Results

A total of 24 patients [12 upper extremity lymphedema (UEL), and 12 lower extremity lymphedema (LEL)] were included and analyzed. The mean age was 54.5 years (38-72 years). The mean circumference reduction rate was 90% and 85% for UEL and LEL, respectively. Infection rate decreased to zero postoperatively in all patients. Ten studies were included in the review: six pooling 220 cases included two-stage procedures, and four pooling 66 cases described one-stage surgeries. All patients who underwent a combined approach reported clinical improvement.

Conclusions

Our combined approach is safe surgical option and allows adequate limb size reduction with faster recovery in selected patients with lymphedema with strong fibroadipose component.

Surgical management of lymphedema: a review of current literature

Lymphedema may be characterized by a progressive clinical course and limitations in improvement despite multi-modality treatment. In westernized countries, it most commonly presents as an undesirable complication of cancer treatment, particularly breast cancer. In the past several decades, surgical treatments for lymphedema have advanced, alongside developments in microsurgery. Lymphovenous anastomosis (LVA) and lymph node transplantation are physiological therapies that may reduce lymphedema through addressing its route cause. Ablative techniques such as liposuction and subcutaneous excision aid in resolving the accumulation of proteinaceous adipose and fibrotic tissue seen in advanced lymphedema. The goal of this review is to examine the outcomes and limitations of current surgical techniques used in lymphedema management.

Combined microvascular breast and lymphatic reconstruction with deep inferior epigastric perforator flap and gastroepiploic vascularized lymph node transfer for postmastectomy lymphedema patients

BACKGROUND

The combination of microvascular breast reconstruction (MBR) and vascularized lymph node transfer (VLNT) in a single-stage procedure is a surgical option for women who desire breast reconstruction and postmastectomy lymphedema surgery. In this study, we present a series of patients who underwent simultaneous lymphatic and MBR with the gastroepiploic VLNT (GE-VLNT) and the deep inferior epigastric perforator (DIEP) flap respectively.

METHODS

Between 2018 and 2019, all consecutive patients diagnosed with lymphedema stage IIb-III International Society of Lymphology who opted to pursue simultaneous MBR with DIEP flap and GE-VLNT were included in this study. Patient demographics, comorbidities, prior radiation therapy, operative characteristics, surgical outcomes and complications were collected and analyzed.

RESULTS

Six patients underwent simultaneous unilateral MBR with DIEP flap and GE-VLNT. The mean age was 48±10.5 years and mean body mass index was 28.2±4.5 kg/m2. The flap survival rate was 100%. One patient required re-exploration due to venous congestion of the lymph node flap but was successfully salvaged. There was no donor site morbidity at the donor or recipient site for the DIEP flap were seen. The mean circumference reduction rate was 30.0%±5.1% (P<0.001). One patient stage III underwent additional liposuction at 12 months postoperative to improve final results.

CONCLUSIONS

The combined use of DIEP flap and GE-VLNT flaps in a single-stage procedure is a safe and reliable surgical option for patients with postmastectomy lymphedema who desire and are suitable for autologous microvascular breast and lymphatic reconstruction.

Preoperative Assessment of Upper Extremity Secondary Lymphedema

Introduction: The purpose of this study was to evaluate the most commonly used preoperative assessment tools for patients undergoing surgical treatment for secondary upper extremity lymphedema. Methods: This was a prospective cohort study performed at a tertiary cancer center specializing in the treatment of secondary lymphedema. Lymphedema evaluation included limb volume measurements, bio-impedance, indocyanine green lymphography, lymphoscintigraphy, magnetic resonance angiography, lymphedema life impact scale (LLIS) and upper limb lymphedema 27 (ULL-27) questionnaires. Results: 118 patients were evaluated. Limb circumference underestimated lymphedema compared to limb volume. Bioimpedance (L-Dex) scores highly correlated with limb volume excess (r2 = 0.714, p < 0.001). L-Dex scores were highly sensitive and had a high positive predictive value for diagnosing lymphedema in patients with a volume excess of 10% or more. ICG was highly sensitive in identifying lymphedema. Lymphoscintigraphy had an overall low sensitivity and specificity for the diagnosis of lymphedema. MRA was highly sensitive in diagnosing lymphedema and adipose hypertrophy as well as useful in identifying axillary vein obstruction and occult metastasis. Patients with minimal limb volume difference still demonstrated significantly impaired quality of life. Conclusion: Preoperative assessment of lymphedema is complex and requires multimodal assessment. MRA, L-Dex, ICG, and PROMs are all valuable components of preoperative assessment.

Lipoaspiration and Lymph Node Transfer for Treatment of Breast Cancer-related Lymphedema: A Systematic Review

Lipoaspiration and venous lymph node transfer have each been described as procedures that would improve symptoms of lymphedema. We aim to describe the efficacy of the combination of lipoaspiration and lymph node transfer and to report the outcomes in breast cancer-related lymphedema patients. The search was conducted by querying the PubMed, EMBASE, and Ovid Medline databases for studies that considered the use of lipoaspiration and venous lymph node transfer as surgical treatment for breast cancer-related lymphedema. Different combinations of the keywords “aspiration lipectomy” AND “lymphedema” AND “lymph node transfer” were used for the search. From a total of 20 articles, five met inclusion criteria. All patients included in these studies had stage II or III lymphedema. Two studies considered lipoaspiration as the first step followed by lymph node transfer, two considered lymph node transfer as the first step followed by lipoaspiration, and one applied both procedures simultaneously. A meaningful volume reduction was achieved in all cases. Patients who underwent lymph node transfer first followed by lipoaspiration appeared to have the best outcomes. This systematic review suggests that the combination of lymph node transfer and lipoaspiration is a potential surgical treatment that may improve outcomes achieved by one single procedure in patients with stage II to III breast cancer-related lymphedema.

Surgical Management of Lower Extremity Lymphedema: A Comprehensive Review

Lymphedema refers to the accumulation of protein-rich fluid in the interstitial spaces. This can occur secondary to congenital malformation of the lymphatic channels or nodes or as a result of an insult that damages appropriately formed channels and nodes. Stagnant, protein-rich lymph initiates an inflammatory response that leads to adipocyte proliferation, fibrous tissue deposition, and increased susceptibility to infections. The end result is permanent disfigurement and dermal changes. Early and accurate diagnosis is essential, since lymphedema is a chronic and progressive problem. When lymphedema affects the lower extremity, it is important to manage it in a way that preserves function and mobility. Early diagnosis also allows for a proactive rather than reactive approach to treatment and utilization of novel physiologic procedures, such as lymphovenous anastomosis and vascularized lymph node transfer. Such interventions slow down disease progression and reduce morbidity by allowing the surgeon to salvage the remaining functional lymphatic channels. When physiologic procedures fail or when faced with a delayed presentation, the addition of excisional procedures can provide a more comprehensive treatment of this debilitating disease. The aim of this article is to review the most current concepts in the surgical management of lower extremity lymphedema.

Feasibility of pedicled vascularized inguinal lymph node transfer in a mouse model: A preliminary study

PURPOSE

Vascularized lymph node transfer is becoming more common in the treatment of lymphedema, but suitable small animal models for research are lacking. Here, we evaluated the feasibility of pedicled vascularized inguinal lymph node transfer in mice.

METHODS

Twenty-five mice were used in the study. An inguinal lymph node-bearing flap with a vascular pedicle containing the superficial caudal epigastric vessels was transferred into the ipsilateral popliteal fossa after excision of the popliteal lymph node. Indocyanine green (ICG) angiography was used to confirm vascularity of the flap. ICG lymphography was performed to evaluate lymphatic flow at 3 and 4 weeks postoperatively. Patent blue dye was injected into the ipsilateral hind paw to observe staining of the transferred lymph node at 4 weeks postoperatively. All transferred lymph nodes were then harvested and histologically evaluated by hematoxylin and eosin staining.

RESULTS

In 16 of the 25 mice, ICG lymphography showed reconnection between the transferred lymph node and the afferent lymphatic vessels, as confirmed by patent blue staining. Histologically, these transferred lymph nodes with afferent lymphatic reconnection significantly regressed in size (0.37 ± 0.24 mm² ) and showed clear follicle formation, whereas those without afferent lymphatic reconnection showed less size regression (1.31 ± 1.17 mm² ); the cell population was too dense to allow identification of follicles.

CONCLUSIONS

We established a mouse model of vascularized lymph node transfer with predictable afferent lymphatic reconnection. Both the vascularization and reconnection might be necessary for functional regeneration of the transferred lymph node.