Lack of Standards for the Detection of Melanoma in Sentinel Lymph Nodes: A Survey and Recommendations

Abstract

Context.-Detection of microscopic melanoma metastases in sentinel lymph nodes drives clinical care; patients without metastases are observed, and patients with metastases are offered completion lymphadenectomy and adjuvant therapy.Objective.-We sought to determine common elements in currently used analytic platforms for sentinel lymph nodes in melanoma patients.Design.-An electronic survey was distributed to 83 cancer centers in North America.Results.-Seventeen responses (20%) were received. The number of sentinel lymph node mapping procedures for melanoma ranged from less than 11 to more than 100 patients per year, with 72% of institutions mapping more than 50 melanoma patients a year. Uniform practices included (1) processing all of the lymph node tissue rather than submitting representative sections and (2) use of immunohistochemical stains if no tumor was identified on the hematoxylin-eosin-stained sections. Significant variability existed regarding the method of sectioning lymph nodes at grossing and in the histology laboratory; most bisected nodes longitudinally (94%) and performed deeper levels into the block (67%), but these were not uniform practices. S-100 was the most commonly used immunohistochemical stain (78%), followed by Melan-A (56%), MART-1 (50%), HMB-45 (44%), tyrosinase (33%), MiTF (11%), and pan-melanoma (6%).Conclusions.-There is a need for a standardized platform for detecting melanoma in sentinel lymph nodes. Current practices by a majority of laboratories and findings in the reported literature support the following: histologic evaluation of all lymph node tissue, use of immunohistochemical stains, bisecting lymph nodes longitudinally, and performing deeper levels into the tissue block.

Sentinel Lymph Node Characterization with a Dual-Targeted Molecular Ultrasound Contrast Agent

“…Specifically, SLN involvement has been shown to be a strong prognostic indicator with less than a 5 % patients diagnosed with a negative SLN presenting with a positive non-SLN [31]. Currently, SLN biopsy is a commonly used tool for evaluating SLNs [32]. SLN biopsy is invasive and carries a substantial morbidity risk.…”

“…SLN biopsy is invasive and carries a substantial morbidity risk. The adverse effect of lymph node resection includes lymphedema, seroma, numbness, tingling, or pain at the site of the surgery [32]. There is, however, a controversy about when to perform biopsies in patients with melanomas less than 1 mm due to less favorable risk-to-benefit ratio of SLN biopsy in this group [33].…”

Utility of sentinel lymph node biopsy for solitary dermal melanomas

“…These factors are intuitively relevant. The pathologic assessment of sentinel nodes is not widely standardized , and the clinical relevancy of micrometastates in sentinel nodes has recently come under focused attention . If a large proportion of SNBx's yield positive nodes—i.e., increased sensitivity for micrometastases—a larger portion of patients may be subjected to CLND procedures which may not offer meaningful therapeutic benefit.…”

Pathology of Melanoma

“…In addition, there is considerable interinstitutional variation in the number of sections studied in the examination of sentinel nodes, and in the use of immunohistochemistry. 29,30 …”