Lack of standards for the detection of melanoma in sentinel lymph nodes: a survey and recommendations

* 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. (Arch Pathol Lab Med. 2013;137:1603-1609; doi: 10.5858/arpa.2012-0550-OA)
More than 80% of patients diagnosed with primary cutaneous melanoma are without clinical evidence of metastatic disease at the time of diagnosis. (1) Patients with localized disease at presentation have [...]