Yield and predictors of radiologic studies for identifying distant metastases in melanoma patients with a positive sentinel lymph node biopsy

Background: It is common to obtain radiological studies around the time of a positive sentinel lymph node biopsy (SLNB) to exclude patients with distant metastases from completion lymph node dissection. The yield of such a work-up is unknown. Results: Patients were identified from a prospectively maintained database. Medical records were reviewed. Results: Over an 8-year period, 181 patients had a positive SLNB. At least one study (computed tomography or magnetic resonance imaging of the brain; chest x-ray; computed tomography of the thorax, abdomen, or pelvis; positron-emission tomography scan; or bone scan) was obtained around the time of SLNB in 178 patients (98%). Studies were obtained after SLNB in 107 patients (59%). Studies ordered after SLNB resulted in indeterminate findings in 51 patients (48% of those studied). Among patients tested after SLNB, four were found to have metastatic disease (positive rate 3.7%). All of these patients had both a thick melanoma and macrometastasis within the SLN. The number of patients with indeterminate findings would be decreased and the yield of the work-up increased by 4 fold, by restricting the work-up to those with thick melanoma and macrometastasis. Conclusions: Radiological studies obtained after a positive SLN produce indeterminate findings in about half of the patients and identify distant disease in 3.7%. Restricting work-up to patients with thick melanoma and macrometastasis on SLNB would spare patients from indeterminate findings and increase the yield of the evaluation.