Futility of fluorodeoxyglucose F 18 positron emission tomography in initial evaluation of patients with T2 to T4 melanoma

Background: Evaluation of newly diagnosed patients with melanoma for metastasis is requisite to treatment planning. The reported diagnostic yield of whole-body conventional radiological imaging in initial staging of patients with melanoma is low. However, the diagnostic yield of positron emission tomography (PET) for distant metastases is unclear. Hypothesis: There is no utility of PET as part of a routine metastatic survey in patients with T2 to T4 melanoma, Design: Retrospective review of a cohort study between December 1998 and July 2004. Setting: University hospital tertiary care center. Patients and Methods: There were 64 patients with T2 to T4 melanomas who underwent PET for detection of occult metastases at our institution. All patients underwent surgical excision of the primary lesion and sentinel lymph node dissection. Data included were pathologic findings of the primary lesion and sentinel lymph nodes, laboratory data, and radiological reports. None of the patients had clinically suspected regional or distant metastases prior to PET. The diagnostic yield of PET was evaluated through retrospective analysis. Positive scans were then correlated for accuracy with follow-up imaging, biopsy, and clinical information when available. Results: Positron emission tomography did not reveal occult distant metastases in any of the patients. Positron emission tomographic scans showed no abnormalities in 94% of these patients. In 2 patients (3%), false-positive findings were reported on PET (muscular activity and intranodal melanocytic nevocellular inclusion). Further, PET was not useful in predicting regional lymph node metastases. Nineteen of 64 patients had positive sentinel lymph nodes, and only 2 (11%) were identified on PET. Overall, PET did not change clinical management in any of the patients. Conclusions: This study suggests no utility for PET in the detection of occult metastases in patients at initial diagnosis of melanoma. Omission of PET imaging from preoperative evaluations for patients with melanoma is recommended.