Extensive pathological analysis of selected melanoma sentinel lymph nodes: high metastasis detection rates at reduced workload.
BACKGROUND
Extensive pathological workup of sentinel lymph nodes (SLNs) in melanoma detects more patients with metastasis-positive SLNs than do routine protocols, but at the cost of high laboratory workloads. We aimed to design a protocol that reduced this workload without compromising metastasis detection.


METHODS
We analyzed 920 SLNs from 321 consecutive patients with melanoma by complete step sectioning and immunohistochemistry. We designed different models to theoretically reduce the number of histological sections examined and compared the results from these simulations with results obtained with our extended protocol, with the restricted national Danish protocol, and with the protocol recommended by the European Organization for Research and Treatment of Cancer (EORTC).


RESULTS
The extended protocol increased the metastasis detection rate by 22% (95% confidence interval, 11-34; 30.8% vs. 25.2%, P < .0001) compared with the national Danish protocol, and it had a similar rate to that reported by the EORTC (30.8% vs. 29.4%, P = .6229). The workload associated with complete step sectioning could be reduced by 40% by focusing step sectioning on the SLNs with the highest gamma counts, while examining SLNs with lower gamma counts with one to three central sections. The false-negative rate for detecting metastases with this reduced protocol was 6% compared with complete step sectioning.


CONCLUSIONS
Combining complete step sectioning of SLNs with immunohistochemistry ensures high metastasis detection rates. Workloads can be markedly reduced with only a slight increase in the false-negative rate by focusing analysis on the SLNs most likely to contain metastases, i.e., those with the highest gamma counts.
Riber-Hansen
Rikke
R
Institute of Pathology, Aarhus University Hospital, Noerrebrogade 44, Aarhus C, 8000, Denmark. rrhan@as.aaa.dk
Sjoegren
Pia
P
Hamilton-Dutoit
Stephen Jacques
SJ
Steiniche
Torben
T
D000951:Antigens, Neoplasm / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism; D005260:Female; D005720:Gamma Rays; D006801:Humans; D007124:Immunoenzyme Techniques; D008207:Lymphatic Metastasis; D058965:MART-1 Antigen; D008297:Male; D008545:Melanoma / Q000000981:diagnostic imaging / Q000556:secondary* / Q000601:surgery; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D009418:S100 Proteins / Q000378:metabolism; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*; D012878:Skin Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D013668:Technetium Tc 99m Aggregated Albumin
D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D058965:MART-1 Antigen; C548667:MLANA protein, human; D009363:Neoplasm Proteins; D019275:Radiopharmaceuticals; D009418:S100 Proteins; D013668:Technetium Tc 99m Aggregated Albumin