Management of popliteal sentinel nodes in melanoma

Interval Sentinel Lymph Nodes With the Use of Routine Lymphoscintigraphy in Extremity Melanoma

INTRODUCTION

Lymphoscintigraphy (LS) helps identify drainage to interval (epitrochlear or popliteal) lymph node basins for extremity melanomas. This study evaluated how often routine LS evaluation identified an interval sentinel lymph node (SLN) and how often that node was found to have metastasis.

METHODS

A single institution, retrospective study identified patients with an extremity melanoma who underwent routine LS and SLN biopsy over a 25-y period. Comparisons of factors associated with the identification of interval node drainage and tumor status were made.

RESULTS

In 634 patients reviewed, 5.7% of patients drained to an interval SLN. Of those biopsied, 29.2% were positive for micrometastases. Among patients with biopsies of both the traditional and interval nodal basins, nearly 20% had positive interval nodes with negative SLNs in the traditional basin. Sex, age, thickness, ulceration, and the presence of mitotic figures were not predictive of identifying an interval node on LS, nor for having disease in an interval node. Anatomic location of the primary melanoma was the only identifiable risk factor, as no interval nodes were identified in melanomas of the thigh or upper arm (P ≤ 0.001).

CONCLUSIONS

Distal extremity melanomas have a moderate risk of mapping to an interval SLN. Routine LS should be considered in these patients, especially as these may be the only tumor-positive nodes. However, primary extremity melanomas proximal to the epitrochlear or popliteal nodal basins do not map to interval nodes, and improved savings and workflow could be realized by selectively omitting routine LS in such patients.

Incidence and patterns of lymphatic drainage to the epitrochlear and popliteal sentinel lymph nodes in malignant melanoma of the distal extremities: a single-institution retrospective study

BACKGROUND

In most cutaneous melanomas of the distal extremity, sentinel lymph nodes (SLNs) are identified in the axillary or inguinal basin; however, they may be occasionally found in the epitrochlear or popliteal basins. The incidence and patterns of lymphatic drainage to the epitrochlear or popliteal SLNs are unclear.

METHODS

To clarify the incidence and clinical characteristics of melanoma draining to these ectopic SLNs, we performed a retrospective study of the patients with distal extremity melanoma who underwent SLN biopsy at the National Cancer Center Hospital between April 2010 and December 2017.

RESULTS

We identified 27 patients with melanoma of the distal upper extremity and 113 patients with melanoma of the distal lower extremity. All patients with distal upper and lower extremity melanomas had SLNs in the axillary and inguinal basins. Epitrochlear SLNs were found in 14.8% (4/27) of the patients with upper extremity melanoma, and the frequency increased by 36.4% (4/11) when the primary melanoma was located in the basilic vein area (P = 0.00188). Popliteal SLNs were found in 21.2% (24/113) of the patients with lower extremity melanoma, and the frequency increased by 37.9% (22/58) when the primary melanoma was located in the lesser saphenous vein area (P < 0.0001).

CONCLUSION

The incidence of SLNs identified in the epitrochlear or popliteal basin is not uncommon, and physicians need to be aware of these ectopic SLNs, especially when the primary melanoma is located in the basilic vein or lesser saphenous vein areas accordingly.

The Lymphatic Drain of Below-Knee Malignant Melanoma: Is the Popliteal Fossa a Ghost Station?

Sentinel lymph node biopsy is fundamental in the staging of primary cutaneous melanoma (PCL), but reported lymphoscintigraphic patterns are very heterogeneous. In this systematic review, we evaluated the role of the popliteal station in below-knee PCL. A systematic search of literature through was conducted on the electronic databases PubMed, SCOPUS, and Web of Science (WOS) to identify eligible studies. A total of 22 studies (n=5673 patients) were included. During the analysis of the included articles, it was not possible to classify patients into the 3 Menes popliteal drainage pattern, obtained by lymphoscintigraphy. The analysis of lymphatic drainage in patients undergoing lymphoscintigraphy for melanoma of the lower extremities below the knee was reported in 5637 patients and the type of lymphatic popliteal drainage was reported only in 5.64% (320 patients). The rate of popliteal lymph nodes melanoma metastases was 1.49%: they were located exclusively at the popliteal level in 0.60%, at the popliteal and inguinal levels in 0.39%, at the popliteal and iliac level in 0.02%, and at the groin level in 0.48%. In conclusion, the most common lymphoscintigraphic pattern is represented by popliteal nodes in-transit or interval nodes, so metastases from below-knee melanomas commonly transit through popliteal nodes stations and arrive to inguinal nodes stations. The popliteal nodes are the primary station in about 5.64% of cases. Larger studies are needed to corroborate these findings.

A case report of metastatic melanoma in the popliteal fossa

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Metastatic melanoma in the popliteal fossa is extremely rare with limited literature available.

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A case of popliteal fossa metastatis following primary diagnosis of right mid-calf malignant melanoma with inguinal metastasis.

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Surgical treatment involves a posterior approach to the popliteal fossa.

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High index of suspicion for early detection of metastasis to the popliteal fossa and inguinal region in distal lower extremity lesions.

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Popliteal lymph nodes could be a primary drainage site or interval nodes.

Introduction

Metastatic melanoma in the popliteal fossa is extremely rare with less than 5% of metastatic deposits from melanomas in the leg and foot draining into the popliteal region, while the majority drain to the inguinal region. If popliteal spread is clinically overlooked, it may lead to recurrence. Together with the accompanying literature review, this case report emphasises the need for thorough clinical and radiological assessment in the management of malignant melanomas of the lower extremity.

Presentation of case

A 66-year-old gentleman presented with metastatic melanoma to the right popliteal fossa three years after the diagnosis of a primary lesion in the right mid-calf with ipsilateral inguinal lymph node metastasis for which he underwent a right wide local excision and complete groin lymph node dissection.

Discussion

Studies show that a lesion anywhere below the knee can metastasize to the popliteal fossa. The groin can be the primary or secondary lymphatic drainage site in conjunction with the popliteal fossa. Concurrent popliteal and inguinal drainage may either reflect two separate lymphatic channels with popliteal nodes being the primary drainage site, or a single channel which drains to the popliteal basin as an interval node. Hence, popliteal lymph nodes should be carefully assessed in distal lower extremity lesions including melanomas. Modalities to delineate lymphatic flow and identify micrometastatic deposits should be used and when metastatic popliteal disease is identified, radical popliteal dissection is advised.

Conclusion

Proper clinical assessment, good surgical technique, a high index of suspicion, and active surveillance are all essential to ensure early detection of metastasis to the popliteal region.

Sentinel Lymph Node Biopsy and Complete Lymph Node Dissection for Melanoma

PURPOSE OF REVIEW

The main surgical treatment for invasive malignant melanoma consists of wide surgical and examination of the sentinel node and in selected cases complete lymph node dissection. The aim of this review is to present data for the optimal surgical management of patients with malignant melanoma.

RECENT FINDINGS

A surgical excision margin of 1-2 cm is recommended for invasive melanoma depending on the thickness of the melanoma. Sentinel node biopsy may be considered for patients with at least T1b melanomas thickness 0.8 to 1.0 mm or less than 0.8 mm Breslow thickness with ulceration, classified as T1b lesion, per recent AJCC guidelines. Two randomized controlled trials have been published-DeCOG (German Dermatologic Cooperative Oncology Group Selective Lymphadenectomy) and MSLT-2 (Multicenter Selective Lymphadenectomy Trial) comparing the complete lymph node dissection (CLND) with observation after positive sentinel node biopsy. In the MSLT-2 study, the disease control rate was improved in the immediate CLND group compared with observation but there was no difference in 3-year melanoma specific survival (86% ± 1.3% and 86% ± 1.2%, respectively; p = 0.42). Isolated limb perfusion (ILP) or isolated limb infusion (ILI) with melphalan and actinomycin D is recommended for large and multiple in-transit metastases and satellite metastases in the extremities when local excision is considered ineffective or too extensive. In light of new adjuvant treatment options and new indications for checkpoint inhibitors, and the lack of survival benefit after CLND, we can expect open surgery to decrease in melanoma disease.

Popliteal sentinel lymph node involvement in melanoma patients

BACKGROUND

Sentinel lymph nodes (SLN) in popliteal basins are rare, and there is controversy in literature regarding their origin, management, and outcomes.

OBJECTIVES

To correlate clinical and pathological features of popliteal basin drainage and analyze the impact of popliteal lymph node drainage on survival.

MATERIALS AND METHODS

Retrospective analysis of SLN biopsies performed at a single institution between 2000 and 2010.

RESULTS

SLN biopsies were performed in 254 patients with melanoma in lower limbs, 247 of which were evaluated. In this group, there were 59 patients (24%) with a positive SLN. Twenty-seven cases (11%) presented with popliteal drainage, one of which lacked concurrent groin drainage. Among these 27 patients, three (11%) had popliteal metastasis, one of which had exclusive involvement of this basin. Popliteal drainage was associated with worse 5-year disease-free survival (DFS) (P = 0.028) but not 5-year overall survival (OS) (P = 0.219) in univariate analysis. In multivariate analysis, Breslow thickness, mitotic index, and positive SLN were prognostic factors for DFS. Only mitotic index correlated significantly with OS (P = 0.044).

CONCLUSIONS

Popliteal drainage seems to be associated with worse prognostic features of the primary tumor.

Long-term treatment outcome after only popliteal lymph node dissection for nodal metastasis in malignant melanoma of the heel: the only "interval node" dissection can be an adequate surgical treatment

We present a patient with malignant melanoma on his heel. Wide local excision was performed, along with sentinel lymph node biopsy of the inguinal and popliteal lesions. The primary site was clear of tumor at all margins; the inguinal nodes were negative, but the popliteal node was positive for metastatic melanoma. Only radical popliteal lymph node dissection was performed. The patient went on to receive adjuvant chemoimmunotherapy. There was no recurrence or complication until the long-term followup. Popliteal drainage from below the knee is uncommon, and the rate of popliteal-positive and inguinal-negative cases is estimated to be less than 1% of all melanomas. There is no established evidence about how to treat lymph nodes in these cases. Because we considered popliteal nodes as a regional, not interval, lymph node basin, only popliteal lymph node dissection was performed, and good postoperative course was achieved. The first site of drainage is the sentinel node, and the popliteal node can be a sentinel node. The inguinal node is not a sentinel node in all lower extremity melanomas. This case illustrates the importance of individual detailed investigation of lymphatic drainage patterns from foot to inguinal and popliteal nodes.