Introduction: Pediatric Spitz nevi can pose significant diagnostic challenges to both clinicians and dermatopathologists when the current image-recognition based gold standard is employed. PRAME (preferentially expressed antigen in melanoma) and/or LINC (long intergeneic non-coding RNA 518) gene expression in adult patients in samples obtained non-invasively via adhesive patches differentiates primary melanomas from atypical nevi and other pigmented lesions with a NPV of over 99%, a sensitivity of 91%, and a specificity of 69%, to help clinicians rule out melanoma and the need for surgical biopsies of atypial pigmented lesions with suspicion for melanoma. Surgically obtained melanomas from adult patients show the same gene expression pattern.
Methods: In this study, we investigate gene expression patterns of pigmented lesions from FFPE tissue block samples (n=23, 9 male, 14 female patients, median age 12) with a focus on differentiating Spitz nevi from melanomas in children and young adults.
Results: PRAME levels were significantly (P less than 0.001) increased based on normalized Ct cycle counts (lower cycle counts indicate higher expression levels) in melanomas (mean Ct 33.83 + 0.54, 95% CI 32.85-34.80) when compared to Spitz nevi (mean Ct 37.21 + 0.98, 95% CI 35.41-39.01) or common nevi (mean Ct 36.94 + 0.80, 95% CI 35.47-38.40), respectively. LINC and 4 control genes showed similar expression levels in all 3 pigmented lesion groups investigated. Clinically and histopathologically complex pediatric Spitz nevi demonstrated gene expression signatures almost identical to gene expression signatures of common pediatric nevi but different from melanomas in children and young adults.
Discussion: PRAME but not LINC gene expression can be a valuable molecular aid to differentiate melanomas from Spitz nevi, groups of pigmented lesions that can be particularly difficult to assess in children and young adults. J Drugs Dermatol. 2018;17(5):574-576.