Background: Tumor staging is crucial for melanoma, of which acral melanoma is the predominant subtype in Asians. 18 F-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) and 18 F-FDG-PET/computed tomography ( 18 F-FDG-PET/CT) serve as noninvasive imaging tools for tumor staging. However, the literature is scarce on the diagnostic value of PET for acral melanoma.
Methods: From January 1, 2006 to November 30, 2022, a total of 352 patients were diagnosed with melanoma at our hospital. Of them, 90 were diagnosed with cutaneous melanoma and underwent preoperative PET/CT for staging and sentinel lymph node biopsy or complete lymph node dissection. Staging of PET/CT was confirmed by histopathology or following imaging. The lymph node biopsy, distant metastasis status, and PET/CT imaging results were analyzed.
Results: Of all the 90 patients with cutaneous melanoma, 72 of them were diagnosed as acral melanoma (80.0%). Compared with the histopathologic results, the lymph nodes were true-positive, true-negative, false-positive, and false-negative in 12, 54, 7, and 17 cases, respectively. The sensitivity of PET/CT for local lymph nodes was 41.4% (95% CI, 23.5%-61.1%), whereas its specificity was 88.5% (95% CI, 77.8%-95.3%). As for the detection of distal metastasis, the PET results were true-positive, true-negative, false-positive, and false-negative in 6, 65, 15, and 4 cases, respectively. The sensitivity of PET for distal metastasis detection was 60.0% (95% CI, 26.2%-87.8%), whereas its specificity was 81.3% (95% CI, 71.0%-89.1%).
Conclusion: Although noninvasive, PET/CT has relatively low sensitivity in regional lymph node evaluations, and fair sensitivity in distal metastasis detection in Asian patients with acral melanoma. Thus, PET/CT may be more useful in patients with clinically palpable nodes or more advanced disease stages.
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