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Most somatic mutations in I BRAF i and I NRAS i oncogenes result in the activation of the mitogen-activated protein kinase (MAPK) pathway and have a role in the development of both benign melanocytic tumours, such as acquired and congenital naevi,[[1]] and melanoma.[3] Dermoscopic features associated with melanomas harbouring I BRAF i mutations have been reported,[[4]] but limited data are available concerning I NRAS i melanomas.[6] The objective was to report the dermoscopic characteristics of melanoma according to mutational status and investigate possible associations between dermoscopic phenotype and genotype. I BRAF i melanomas were mostly superficial spreading melanomas (50.0%), with trunk localization (39.5%), while I NRAS i melanomas were mostly found on the limbs (38.1%). In summary, the results confirm that peppering and blue-white veil were present more frequently in I BRAF- i and I NRAS i -mutated melanomas compared to WT melanomas, while the presence of pseudopods and radial projections was found more frequently only in melanomas with a I BRAF i mutation. [Extracted from the article]

Activating mutations in GNAQ, GNA11, CYSLTR2, and PLCB4 genes are regarded as the main oncogenic drivers of blue nevi (BN) and blue malignant melanocytic tumors. Here we report 4 cases of blue melanocytic neoplasms devoid of these mutations but harboring GRM1 gene fusions. In this short series, there was no gender predominance (sex ratio, 1). The mean age at diagnosis was 40 years (range, 12-72). Tumors were located on the face (n = 2), forearm (n = 1), and dorsum of the foot (n = 1). Clinically, a plaque-like pre-existing BN was found in 2 cases, including a deep location; another case presented as an Ota nevus. Two cases were diagnosed as melanoma ex-BN, one as an atypical BN, and one as a plaque-like BN. Microscopic examination revealed a dermal proliferation of dendritic melanocytes in a sclerotic stroma. A dermal cellular nodule with atypia and mitotic activity was observed in 3 cases. Genetic investigation by whole exome RNA sequencing revealed MYO10::GRM1 (n = 2) and ZEB2::GRM1 (n = 1) fusions. A GRM1 rearrangement was identified by fluorescence in situ hybridization in the remaining case. SF3B1 comutations were present in the 2 melanomas, and both had a MYO10::GRM1 fusion. Array comparative genomic hybridization was feasible for 3 cases and displayed multiple copy number alterations in the 2 melanomas and limited copy number alterations in the atypical BN, all genomic profiles compatible with those of classical blue lesions. GRM1 was overexpressed in all cases compared with a control group of blue lesions with other typical mutations. Both melanomas rapidly developed visceral metastases following diagnosis, with a fatal outcome in one case and tumor progression under palliative care in the other. These data suggest that GRM1 gene fusions could represent an additional rare oncogenic driver in the setting of BN, mutually exclusive of classical canonical mutations, especially in plaque-type or Ota subtypes., (Copyright © 2023 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.)

Background: Congenital nail matrix nevi (NMN) are difficult to diagnose because they feature clinical characteristics suggestive of adult subungual melanoma. Nail matrix biopsy is difficult to perform, especially in children., Objective: To describe the initial clinical and dermatoscopic features of NMN appearing at birth (congenital) or after birth but before the age of 5 years (congenital-type)., Methods: We conducted a prospective, international, and consecutive data collection in 102 hospitals or private medical offices across 30 countries from 2009 to 2019., Results: There were 69 congenital and 161 congenital-type NMNs. Congenital and congenital-type NMN predominantly displayed an irregular pattern of longitudinal microlines (n = 146, 64%), reminiscent of subungual melanoma in adults. The distal fibrillar ("brush-like") pattern, present in 63 patients (27.8%), was more frequently encountered in congenital NMN than in congenital-type NMN (P = .012). Moreover, congenital NMN more frequently displayed a periungual pigmentation (P = .029) and Hutchinson's sign (P = .027) than did congenital-type NMN., Limitations: Lack of systematic biopsy-proven diagnosis and heterogeneity of clinical and dermatoscopic photographs., Conclusion: Congenital and congenital-type NMN showed worrisome clinical and dermatoscopic features similar to those observed in adulthood subungual melanoma. The distal fibrillar ("brush-like") pattern is a suggestive feature of congenital and congenital-type NMN., Competing Interests: Conflicts of interest None disclosed., (Crown Copyright © 2022. Published by Elsevier Inc. All rights reserved.)

Competing Interests: Conflicts of interest None disclosed.

Purpose: Vismodegib is approved for the treatment of locally advanced basal cell carcinoma (laBCC), but some cases demonstrate intrinsic resistance (IR) to the drug. We sought to assess the frequency of IR to vismodegib in laBCC and its underlying genomic mechanisms., Experimental Design: Response to vismodegib was evaluated in a cohort of 148 laBCC patients. Comprehensive genomic and transcriptomic profiling was performed in a subset of five intrinsically resistant BCC (IR-BCC)., Results: We identified that IR-BCC represents 6.1% of laBCC in the studied cohort. Prior treatment with chemotherapy was associated with IR. Genetic events that were previously associated with acquired resistance (AR) in BCC or medulloblastoma were observed in three out of five IR-BCC. However, IR-BCCs were distinct by highly rearranged polyploid genomes. Functional analyses identified hyperactivation of the HIPPO-YAP and WNT pathways at RNA and protein levels in IR-BCC. In vitro assay on the BCC cell line further confirmed that YAP1 overexpression increases the cell proliferation rate., Conclusions: IR to vismodegib is a rare event in laBCC. IR-BCCs frequently harbor resistance mutations in the Hh pathway, but also are characterized by hyperactivation of the HIPPO-YAP and WNT pathways., (©2022 The Authors; Published by the American Association for Cancer Research.)