Next‐generation sequencing improves agreement and accuracy in the diagnosis of Spitz and spitzoid melanocytic lesions

BACKGROUND: Spitzoid melanocytic neoplasms can be challenging to diagnose on histopathology alone. Next‐generation sequencing (NGS) offers promise as a valuable aid in the diagnosis. Recently, one study reported increased inter‐rater agreement in the diagnosis of spitzoid melanocytic neoplasms among 20 expert melanoma pathologists after incorporating NGS data. We hypothesized that NGS would carry a similar utility in a broader group of dermatopathologists and general pathologists. METHODS: Sixty‐three participants of a live online (www.Dermpedia.org) CME course rendered a diagnosis on 70 cases composed of melanocytic neoplasms with spitzoid features. In Survey 1, cases included H&E slides and demographic information only, while Survey 2 included NGS data. RESULTS: With NGS information, inter‐rater agreement significantly improved from “fair” to “almost perfect” and from “fair” to “substantial” for categorizing lesions as Spitz versus non‐Spitz and conventional melanoma versus not, respectively. There was also an increase in diagnostic accuracy, evidenced by improved recognition of three metastatic tumors as being conventional melanomas. CONCLUSION: The study supports the adoption of NGS as a valuable diagnostic adjunct for both expert and broader dermatopathologists in their assessments of spitzoid neoplasms.