A Clinical, Morphologic, and Molecular Comparison of Bonafide Spitz Melanomas and ASTs in the Pediatric Population.

Pediatric Spitz melanoma (SM) with bonafide metastatic disease is rare. In this study, we assembled the largest cohort to date of pediatric SM with a verified Spitz-associated genomic driver and clinical follow-up demonstrating bonafide metastasis. We compared the clinical, morphologic, and molecular features of these SMs to a control cohort of 57 pediatric atypical Spitz tumors (ASTs).

Clinical, Morphologic, and Genomic Differences in Deep-Penetrating Nevi and Deep-Penetrating Nevus-like Melanomas.

Deep-penetrating nevi (DPNs) are characterized by activating mutations in the MAP kinase and Wnt/β-catenin pathways that result in large melanocytes with increased nuclear atypia, cytoplasmic pigmentation, and often mitotic activity. Together with a lack of maturation, this constellation of findings creates challenges for pathologists to distinguish DPN from DPN-like melanoma. To assess the utility of next-generation sequencing (NGS) in resolving this diagnostic dilemma, we performed NGS studies on 35 lesions including 24 DPNs and 11 DPN-like melanomas to characterize the specific genomic differences between the 2 groups and elucidate the genetic events involved in malignant transformation of DPNs.