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Patients with metastases in the sentinel node (SN) are advised to undergo complete lymph node dissection, although the majority of them will have no further metastatic disease. Some of these patients undergo unnecessary surgery. In this study, we tried to predict the likelihood of further non-SN metastases on the basis of earlier published micromorphometric classifications of SN metastases. Metastases in the SN were re-evaluated on the basis of the microanatomic location of the lesions according to the Dewar's criteria, the S-classification of SN, and tumor burden in accordance with the Rotterdam criteria. The results of these classifications were correlated with the presence of further non-SN metastases. Specimens of 124 positive-SN basins and subsequent complete lymph node dissection were investigated. Further metastases in non-SNs were found in 30 lymph node basins (24.2%). All of the above-mentioned classification systems were significantly correlated with non-SN tumor status. Especially, in patients with SN metastases in subcapsular location, a maximum depth of invasion of less than 0.3 mm (stage I according to the S-classification) or metastases of less than 0.1 mm in diameter had a very low probability of further non-SN metastases (0-5%). The validity of earlier published classifications of SN metastases-based on the micromorphometric criteria in predicting non-SN status was confirmed. Especially, in patients with subcapsular metastases, SI stage metastases or metastases of less than 0.1 mm had a very low risk of further non-SN metastases.

The purpose of this study was to identify melanoma patients with positive sentinel lymph nodes (SLNs) at increased risk for further metastases in this specific lymph node basin. A series of consecutive patients with primary malignant melanoma stage I and II were evaluated retrospectively. The results of SLN biopsy in 26 patients with positive SLNs were compared with those of complete regional lymph node dissection (RLND) using the recently published S-classification of SLNs. The results of S-classification of SLNs were correlated with the outcome of complete RLND. There was a significant correlation between the S stage of positive SLNs and the results of complete RLND (P=0.02). Only patients with SIII stage (n=4) SLNs were found to have further metastases in the residual lymph node basin. The present study indicates that patients with SI stage and SII stage SLNs rarely have further metastases in the specific lymph node basin.

The most powerful predictor for recurrence and survival in patients with primary malignant melanoma is the presence or absence of lymph node metastases. In the present study, 18-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) findings were compared with histopathological results of sentinel lymph node biopsy (SNB). The purpose was to determine the value of FDG-PET in predicting regional lymph node involvement in patients with primary malignant melanoma stage I and II. Forty-eight consecutive patients with primary cutaneous melanoma stage I (Breslow thickness > 1 mm) and II underwent FDG-PET scans, preoperative lymphoscintigraphy, and SNB. The FDG-PET and SNB results were interpreted independently of each other and then compared. Of the 48 patients included in the study, eight (16.7%) had a positive SNB. PET was positive in only one patient with a positive SNB, yielding a sensitivity of 13%. All other positive sentinel nodes could not be detected by metabolic FDG-PET imaging. Our study revealed that FDG-PET is obviously not an adequate screening test for subclinical and sonographically inconspicuous lymph node metastases in patients with malignant melanoma stage I and II. The low sensitivity is probably due to the small size of metastatic deposits in sentinel nodes. Therefore, SNB remains the technique of choice for evaluating the histological status of lymph node basins in patients with early-stage cutaneous melanoma.