Diagnostic Utility of PRAME Immunohistochemistry for Distinguishing Acral Melanoma From Acral Melanocytic Nevi
Issued Date
2026-01-01
Resource Type
ISSN
03036987
eISSN
16000560
Scopus ID
2-s2.0-105042115446
Journal Title
Journal of Cutaneous Pathology
Rights Holder(s)
SCOPUS
Bibliographic Citation
Journal of Cutaneous Pathology (2026)
Suggested Citation
Phatcharamaneepakorn K., Sitthinamsuwan P., Pattanaprichakul P., Chairatchaneeboon M., Yodrabum N. Diagnostic Utility of PRAME Immunohistochemistry for Distinguishing Acral Melanoma From Acral Melanocytic Nevi. Journal of Cutaneous Pathology (2026). doi:10.1111/cup.70163 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/117470
Title
Diagnostic Utility of PRAME Immunohistochemistry for Distinguishing Acral Melanoma From Acral Melanocytic Nevi
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Abstract
Introduction: Preferentially expressed antigen in melanoma (PRAME) immunohistochemistry helps distinguish non-acral melanocytic lesions, but few studies have addressed its value in acral lesions. We aimed to identify an optimal PRAME cut-off score to differentiate acral melanoma (AM) from acral melanocytic nevi (AMN). Methods: Formalin-fixed, paraffin-embedded specimens of AM, AMN, and small biopsy of atypical melanocytic lesions (AMLs) were included. PRAME staining was performed. Expression was categorized into five groups: 0 (0%), 1+ (1%–25%), 2+ (26%–50%), 3+ (51%–75%), and 4+ (> 75%). PRAME nuclear expression was compared between AM and AMN to identify the best cut-off score, which was then assessed in small-sized biopsies of AML specimens. Results: We analyzed 62 AMs, 62 AMNs, and 23 AMLs. A PRAME score of ≥ 3+ optimally differentiated AM from AMN (sensitivity 80.6%, specificity 98.4%, positive predictive value 98%, and negative predictive value 83.6%). PRAME expression score ≥ 3+ was strongly associated with AM, whereas AMN showed expression score < 3+ (p < 0.001). However, one AM was completely negative for PRAME, and one AMN exhibited strong PRAME staining. Conclusions: PRAME immunohistochemistry with a cut-off of ≥ 3+ is useful for differentiating AM from AMN. However, false positivity and negativity of PRAME expression must be considered.