Track: Clinical Studies

Abstract:

Background: Ambiguous melanocytic neoplasms in the pediatric population pose a diagnostic quandary. Ancillary tests such as the 23-gene expression profile (23-GEP) are intended to augment H&E evaluation of these ambiguous melanocytic neoplasms. While developed and validated in patients of all ages, the 23-GEP has not been evaluated specifically in the pediatric population. Here, we describe the performance of 23-GEP in patients <18 years of age.

Methods: Melanocytic neoplasms from patients <18 years of age with 23-GEP results were obtained from 6 sites. All neoplasms underwent digital histopathological review by three expert dermatopathologists. Neoplasms with conflicting diagnoses (i.e. both a benign and malignant designation) were excluded from analyses. Neoplasms achieving a majority designation were included in the performance calculations (n=201). Accuracy metrics were calculated with 23-GEP intermediate results reported as a separate metric.

Results: One hundred and eighty-three nevi and 18 melanomas were included in this cohort. In pediatric patients, the 23-GEP test demonstrated 92.3% (95% CI, 64.0–99.8%) sensitivity, 86.1% (79.8–91.0%) specificity, 86.9% (76.0–91.7%) positive predictive value, and 91.8% (69.9–99.8%) negative predictive value; 11.4% of neoplasms received an intermediate result. These metrics do not deviate significantly from previously published studies using all-aged patients.

Conclusions: The 23-GEP test performance in a pediatric population was similar to that seen in all-aged cohorts. These data support use of 23-GEP as an ancillary test that can be integrated with clinical and histopathologic information to guide final diagnosis of melanocytic neoplasms in pediatric patients.