The role of minor lymph node basins for malignant melanoma of the distal extremities–A meta-analysis

Abstract

Background

In melanoma, nodal status of major lymph node basins are commonly assessed; however, minor lymph node basins (epitrochlear and popliteal regions) are often overlooked. Significant variability in reported incidences of lymphatic drainage and metastasis to these areas exists. By systematically reviewing existing literature and examining studies specifically focusing on the distal extremity, we review the rates of drainage and metastasis to these lesser studied regions and assess the implications for routine clinical examination and care.

Methods

A literature search was performed to identify studies evaluating outcomes of SLNB and clinical metastasis to minor node basins in distal extremity melanoma. PUBMED, EMBASE and COCRANE databases were searched. The primary outcome measure was the location of sentinel node at SLNB. The secondary outcome measures were the rates of micro and macro metastasis. Data synthesis was conducted using the Stuart—Ord method.

Results

259 articles were screened and 50 examined in detail. 10 studies were identified as suitable for synthesis of data, representing 7346 distal extremity melanomas. Pooled proportion of drainage to epitrochlear and popliteal nodes on SLNB were 0.14 and 0.09 and respectively. Rates of positive nodes at SLNB were equivalent to major lymph node basins.

Conclusions

In any distal extremity, there is approximately a 1 in 10 chance of melanomas primarily draining to a minor nodal basin. In the upper extremity, this is higher at approximately 1 in 7. Risk of metastasis is equivalent to that of a major lymph node basins. We propose that clinical examination of minor nodal basins, in addition to performing SPECT-CT lymphoscintigraphy and inclusion of minor basins in ultrasongography, be employed to better detect micro and macrometastasis to these regions.