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Cutaneous BAP1-inactivated melanocytomas (BIM) are melanocytic proliferations defined histopathologically by an epithelioid, predominantly dermal melanocytic proliferation with loss of BAP1, and have been largely characterized in adult patients but less well-described in pediatric cohorts. BIM share overlapping histological features with those seen in Spitz nevi; however, unlike Spitz nevi, the majority of BIM carry both BAP1 and BRAF V600E mutations. This study investigated the potential overlap of BIMs with pediatric Spitz nevi by performing immunohistochemical staining of BAP1 and BRAF V600E on pediatric melanocytic tumors with banal Spitz and dermal features. None of the stained tumors in our study exhibited the concurrent BAP1 loss and BRAF V600E positivity that are characteristic of adult BIM, suggesting that this is a low-frequency mutation among banal tumors in the pediatric population., (© 2024 Wiley Periodicals LLC.)

Background/objectives: The diagnostic distinction between atypical Spitz tumor (AST) and malignant melanoma (MM) in pediatric tumors is challenging. Molecular tests are increasingly used to characterize these neoplasms; however, limited studies are available in pediatric patients. This study aimed to provide a genomic comparison of pediatric MM and AST in the context of comprehensive clinical annotation., Methods: Pediatric patients diagnosed with MM (n=11) and AST (n=12) were compared to a cohort of 693 adult melanoma patients. DNA next-generation sequencing assessed kinase gene fusions, tumor mutational burden, sequence variants, copy number alterations, structural variants, microsatellite instability, and mutational signatures., Results: Seven AST cases and eight MM cases were successfully sequenced. Kinase gene fusions were identified in both the MM and AST cohorts (NTRK1, ROS1, and MET). MM cases had TERT, BRAF, and CDKN2A alterations, which were not identified in the AST cohort. Tumor mutational burden (TMB) analysis showed pediatric ASTs had an average of 2.82 mutations/Mb, pediatric MM had an average of 5.7 mutations/Mb, and adult MM cases averaged 18.8 mut/Mb. One pediatric MM case had an elevated TMB of 15 mutations/Mb and a UV mutational signature., Conclusions: These data expand our understanding of pediatric malignant melanoma. The differences between the molecular signatures for AST and MM are not statistically significant, and histopathology remains the gold standard for the diagnosis of pediatric AST and MM at this time. With more data, molecular studies may provide additional support for diagnosis and targeted therapeutics., (© 2022 Wiley Periodicals LLC.)

Patients are commonly referred to pediatric dermatology for the evaluation of pigmented lesions. For families, pediatricians, and dermatologists alike, malignancy is the main fear. In the past few decades, there has been evolving literature to inform diagnosis and management. This article provides an update on the clinical, histopathologic, and ancillary testing for 3 categories of particularly challenging pigmented lesions: congenital melanocytic nevi, spitzoid neoplasms, and pediatric melanoma., Competing Interests: Disclosure D.W. Bartenstein: MRK (stock, self); DVA (stock, spouse); ANTM (stock, spouse); PRSC (stock, spouse); AMAG (stock, spouse). E.B. Hawryluk: UpToDate, Inc. (royalty, author/reviewer); Purity Brands, LLC (consultant); Gritstone Oncology, Inc. (salary, stock spouse); PathAI (stock and advisory board, spouse)., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Spitzoid proliferations range from Spitz naevi to melanomas. There are few studies describing clinical features and outcomes in the paediatric population., Objectives: To determine the clinical features and outcomes of a large paediatric cohort with histopathologically confirmed Spitz tumours., Methods: This was a retrospective cohort study of patients seen at Boston Children's Hospital who were aged < 20 years and had a histopathological diagnosis of spitzoid proliferation from 1 January 1994 to 23 October 2012., Results: In total 595 patients with 622 spitzoid proliferations were identified (median age 7·4 years, interquartile range 4·6-11·7). Overall 512 proliferations (82·3%) were typical, 107 (17·2.%) were atypical and three (0·5%) were melanomas. The median ages at biopsy were 7·4, 7·2 and 17·2 years, respectively, and there was a significant difference in age at biopsy for patients with typical or atypical proliferations vs. melanoma (P < 0·01). Among samples with positive margins (n = 153), 55% (54 of 98) of typical proliferations, 77% (41 of 53) of atypical proliferations and 100% (two of two) of melanomas were re-excised. Six patients had sentinel lymph node biopsy performed, with three patients demonstrating nodes positive for melanocytic cells. Within a median follow-up of 4·1 years for the full cohort there were no related deaths., Conclusions: Spitz tumours have strikingly benign outcomes in the paediatric population, although this study is limited by the low number of melanomas and restriction to a single paediatric institution. Aggressive management recommendations should be reconsidered for children and adolescents with banal-appearing Spitz naevi, based on the clinically indolent behaviour in this cohort., (© 2018 British Association of Dermatologists.)