Diagnostic value of 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography imaging in acral melanoma–predominant Asian patients

Abstract

Background: Tumor staging is crucial for melanoma, of which acral melanoma is the predominant subtype in Asians. 18F-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) and 18F-FDG-PET/computed tomography (18F-FDG-PET/CT) serve as non-invasive 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, seven, and 17 cases, respectively. The sensitivity of PET/CT for local lymph nodes was 41.4% (95% confidence interval [CI], 23.5–61.1%), while 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 six, 65, 15, and four cases, respectively. The sensitivity of PET for distal metastasis detection was 60.0% (95% CI, 26.2–87.8%), while its specificity was 81.3% (95% CI, 71.0–89.1%). Conclusion: Although non-invasive, 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 stage.

Comparative transcriptomic analysis reveals differences in gene expression and regulatory pathways between nonacral and acral melanoma in Asian individuals

“…Compared with Western countries, Asian countries, including Taiwan, report a lower incidence of melanoma 6 . However, in Asian countries, melanoma is often diagnosed at more advanced stages, resulting in lower response rates to targeted therapy and immunotherapy, which, in turn, leads to a disproportionately high mortality rate 7–11 . These unique challenges are influenced by racial and regional differences in the disease profile.…”