Malignant melanoma metastasis to the sentinel node in the popliteal fossa

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.

Diagnostic Accuracy and Impact of Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Preoperative Staging of Cutaneous Malignant Melanoma: Results of a Prospective Study in Indian Population

The aim of the study was to evaluate the diagnostic accuracy of positron emission tomography/computed tomography (PET/CT) in staging patients with primary cutaneous malignant melanoma (CMM). We further compared the performance of PET/CT with conventional imaging (CI) (CT and ultrasonography [USG]) and assessed the impact of PET/CT on disease management. This was a single institution, prospective, double-blinded study, recruiting a total of 70 treatment naïve patients. The sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of PET/CT for N staging were 86%, 96%, 80%, and 97%, respectively. The sensitivity, specificity, NPV, and PPV of PET/CT for M staging were 87%, 100%, 93%, and 100%, respectively. The diagnostic accuracy of the PET/CT was superior to CI for N staging (90% vs. 84% for CT and 80% for USG) and M staging (95% vs. 90% for CT). No statistically significant difference was noted between PET/CT and CI for N staging (PET/CT vs. CT, P = 0.125; PET/CT vs. USG, P-0.063) or M staging (PET/CT vs. CT, P = 0.125). PET/CT upstaged 23% of patients with clinically localized disease and 58% of patients with clinically palpable regional nodes. To conclude, fluorodeoxyglucose PET/CT is a highly sensitive and specific imaging modality for preoperative staging of primary CMMs. PET/CT impacts disease management in significant number of patients and should be especially recommended in all patients with clinically palpable regional nodes.

Popliteal lymph node dissection for metastases of cutaneous malignant melanoma

Popliteal lymph node dissection is performed when grossly metastatic nodal disease is encountered in the popliteal fossa or after microscopic metastasis is found in interval sentinel nodes during clinical staging of cutaneous malignant melanoma. Initially, an S-shaped incision is made to gain access to the popliteal fossa. A careful en bloc removal of fat tissue and lymph nodes is made to preserve and avoid the injury of peroneal and tibial nerves as well as popliteal vessels, following the previous recommendations. This rare surgical procedure was successfully employed in a patient with cutaneous malignant melanoma and nodal metastases at the popliteal fossa. The technique described by Karakousis was reproduced in a step-by-step fashion to allow anatomical identification of the neurovascular structures and radical resection with no post-operative morbidity and prompt recovery. Popliteal lymph node dissection is a rarely performed operative procedure. Following a lymphoscintigraphic examination of the popliteal nodal station, surgeons can be asked to explore the popliteal fossa. Detailed familiarity of the operative procedure is necessary, however, to avoid complications.

Management of popliteal sentinel nodes in melanoma

BACKGROUND

Although most melanomas on the distal lower extremity drain exclusively to inguinal lymph nodes, a small percentage (<5%) drain to interval nodes in the popliteal basin. We investigated a possible relationship between tumor-draining popliteal and inguinal nodes in patients with lower-extremity melanoma.

STUDY DESIGN

We queried our melanoma database to identify patients who underwent sentinel node biopsy (SNB) for an infrapopliteal melanoma. Patterns of nodal drainage and nodal metastasis were analyzed.

RESULTS

Of 461 patients who underwent SNB for a primary infrapopliteal melanoma, 15 (3.2%) had drainage to the popliteal basin. Thirteen melanomas were on the posterior leg and foot, and 2 were on the anterior lower leg. Mean Breslow thickness was 2.4 mm. All 15 patients with popliteal drainage also had inguinal drainage and therefore underwent concurrent inguinal and popliteal SNB. The average number of popliteal sentinel nodes was 1.4 (range 1 to 3). Eight patients (53%) had a tumor-positive popliteal sentinel node, and 6 of the 8 underwent completion popliteal lymphadenectomy. Four of the 8 patients (50%) also had tumor-positive inguinal sentinel nodes; all underwent complete inguinal lymphadenectomy. We also identified 9 additional patients who underwent SNB for locoregional recurrent melanomas of the infrapopliteal leg. Three (33%) of these patients had concurrent inguinal and popliteal SNB, with 1 isolated tumor-positive popliteal node found.

CONCLUSIONS

In our series, a high percentage of popliteal sentinel lymph nodes contained metastases, and these patients frequently also had inguinal metastases. In our patients, all inguinal metastases were associated with concomitant popliteal metastases. Although it is anatomically separate, the inguinal basin appears to be a functional extension of the popliteal basin.

An amelanotic malignant melanoma masquerading as hypergranulation tissue

We report a case of amelanotic malignant melanoma occurring in the nail sulcus of the hallux, which on initial presentation was mistaken for hypergranulation tissue due to an in-growing toenail. We highlight the importance of this differential diagnosis as such lesions can have serious sequelae.

Popliteal lymphadenectomy for treating metastatic melanoma: case report

CONTEXT

Regional lymph node involvement in patients with malignant melanomas has been associated with poor prognosis. In-transit metastases also lead to poor long-term survival. Whereas for nodal disease only regional lymphadenectomy offers adequate locoregional control, for in-transit metastasis both local excision and isolated limb perfusion with chemotherapy plus tumor necrosis factor-alpha can be used for disease control. In cases of tumors located in the distal region of the legs, the lymphatic dissemination most commonly observed is to the inguinal chain. Consequently, therapeutic inguinal lymphadenectomy or even selective lymphadenectomy (sentinel lymph node biopsy) have been recommended. On the other hand, involvement of the popliteal chain is very rare. When this occurs, popliteal lymphadenectomy should be indicated. Local excision may be the logical approach for a few small in-transit metastases because of the low morbidity in this procedure, when compared with isolated limb perfusion.

CASE REPORT

A case of melanoma of the heel with popliteal chain involvement and in-transit metastases is presented. This was treated by means of regional lymphadenectomy plus in-transit metastases excision, with a good postoperative course.

Resection in the popliteal fossa for metastatic melanoma

BACKGROUND

Traditionally metastatic melanoma of the distal leg and the foot metastasize to the lymph nodes of the groin. Sometimes the first site of nodal disease can be the popliteal fossa. This is an infrequent event, with rare reports in literature and when it occurs, radical popliteal node dissection must be performed.

CASE PRESENTATION

We report a case of a 36-year old man presented with diagnosis of 2 mm thick, Clark's level II-III, non ulcerated melanoma of the left heel, which developed during the course of the disease popliteal node metastases, after a superficial and deep groin dissection for inguinal node involvement. Five months after popliteal lymph node dissection he developed systemic disease, therefore he received nine cycles of dacarbazine plus fotemustine. To date (56 months after prior surgery and 11 months after chemotherapy) he is alive with no evidence of disease.

CONCLUSION

In case of groin metastases from melanoma of distal lower extremities, clinical and ultrasound examination of ipsilateral popliteal fossa is essential. When metastatic disease is found, radical popliteal dissection is the standard of care. Therefore knowledge of anatomy and surgical technique about popliteal lymphadenectomy are required to make preservation of structures that if injured, can produce a permanent, considerable disability.

Implications of Popliteal Lymph Node Detected by Sentinel Lymph Node Biopsy

BACKGROUND

Although there is lymphatic flow into the popliteal fossa from a skin tumor located in the lower leg, popliteal metastasis is extremely rare. Recently, sentinel lymph nodes outside traditional nodal basins have been identified. This study investigated the incidence of sentinel nodes in the popliteal region and the indication for biopsy.

METHODS

Fourteen patients with various skin cancers involving the lower extremities (nine melanomas, four squamous cell carcinomas, and one sweat gland carcinoma) underwent lymphoscintigraphy and excision with sentinel lymph node biopsy.

RESULTS

In all 14 patients, hot spots showed accumulation in the groin region. Five of 14 patients (36%) demonstrated popliteal sentinel nodes in addition to the inguinal nodes. Three of five popliteal sentinel nodes were histologically studied. A patient with acral melanoma demonstrated micrometastasis of melanoma cells in a popliteal node but not in the groin node.

CONCLUSION

This study demonstrates that sentinel lymph nodes located in the popliteal fossa are frequently detected by lymphoscintigraphy and that biopsy should be performed if popliteal nodes are identified.

Popliteal Lymph Node Dissection

Most sentinel nodes are located in the cervical, axillary, and inguinal nodal basins. Sometimes, however, sentinel nodes exist outside these traditional nodal basins. Popliteal nodal metastasis is relatively uncommon, and popliteal lymph node dissection is infrequently necessary. However, with lymphoscintigraphic identification of popliteal sentinel nodes, surgeons are more frequently called on to address the popliteal nodal basin. Therefore, knowledge of the anatomy and surgical technique for popliteal lymphadenectomy is essential. This case study illustrates the importance of considering the approach to the popliteal lymph node basin for patients with melanoma.