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Li A, Warren SJ, Umphress BA, Alomari AK. Histopathologic, genomic, transcriptomic, and functional characteristics of eight melanocytic tumors with BRAF fusions showing stronger MAPK pathway activation compared to BRAF V600E tumors. J Cutan Pathol 2024. [PMID: 39171578 DOI: 10.1111/cup.14704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 07/29/2024] [Accepted: 08/02/2024] [Indexed: 08/23/2024]
Abstract
BACKGROUND Activating BRAF gene alterations are central to melanocytic tumor pathogenesis. A small, emerging subset of melanocytic tumors driven by BRAF fusions has distinct therapeutic implications and has been described to have Spitzoid morphology patterns. However, such morphological patterns do not encompass all cases, and little is known about the functional molecular events. MATERIALS AND METHODS We conducted a retrospective search through our molecular archives to identify melanocytic tumors with BRAF fusions. We reviewed clinical, histopathological, and genomic features. We further explored transcriptomic and protein-level findings. RESULTS Histopathologic patterns varied, with many cases without a distinctive pattern. We identified novel and diverse BRAF gene fusion partners. Differential transcriptomic analysis between low-risk BRAF fusion tumors and reference BRAF V600E tumors showed no differentially expressed genes. However, quantitatively stronger MAPK pathway activation of BRAF fusion tumors over BRAF V600E tumors was demonstrated by statistically significant stronger staining of p-ERK immunohistochemistry. Gene-specific RNA analysis shows comparable BRAF transcript levels between the two groups. DISCUSSION AND CONCLUSION The quantitatively stronger activation of the MAPK pathway of BRAF fusion tumors, instead of qualitatively different transcriptomes, may account for the morphology difference from conventional BRAF V600E tumors. BRAF fusions likely act through dysregulated protein function rather than RNA upregulation related to the characteristics of the fusion partners.
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Affiliation(s)
- Aofei Li
- IU Health Pathology Laboratory, Indiana University, Indianapolis, Indiana, USA
| | - Simon J Warren
- IU Health Pathology Laboratory, Indiana University, Indianapolis, Indiana, USA
| | - Brandon A Umphress
- IU Health Pathology Laboratory, Indiana University, Indianapolis, Indiana, USA
| | - Ahmed K Alomari
- IU Health Pathology Laboratory, Indiana University, Indianapolis, Indiana, USA
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Delsupehe L, Steelandt T, Lemahieu J, Volders PJ, Geerdens E, Berden S, Daniels A, Froyen G, Maes B. Novel gene fusion discovery in Spitz tumours and its relevance in diagnostics. Virchows Arch 2024; 485:269-279. [PMID: 37731064 DOI: 10.1007/s00428-023-03649-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 09/07/2023] [Accepted: 09/08/2023] [Indexed: 09/22/2023]
Abstract
In addition to morphologic analysis, molecular diagnostic work up of Spitz tumours is often of great value for their accurate diagnosis/classification. Nowadays, next-generation sequencing (NGS) is the predominant screening method in molecular diagnostics. Up to 80% of these melanocytic neoplasms comprise gene fusions as genetic anomalies for which the driver codes for a protein harbouring a kinase domain. However, because of the variety of fusion partners the use of PCR-based targeted enrichment NGS methods is not recommended. We describe a series of four Spitz tumour samples in which distinct gene fusions were detected by hybridisation-based capture NGS (TPM3::ALK, LIMA1::ROS1, LRRFIP2::ROS1 and MYO5A::RET). Two of these fusions are not previously described. All 4 fusions were confirmed by reverse transcription-PCR. These findings demonstrate the need for molecular analysis that can detect unknown fusions in Spitz neoplasms for optimal diagnosis.
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Affiliation(s)
- Louis Delsupehe
- Laboratory for Molecular Diagnostics, Department of Clinical Biology, Jessa Hospital, Hasselt, Belgium
- Department Jessa & Science, LCRC (-MHU), Hasselt, Belgium
- Faculty of Medicine and Life Sciences, University of Hasselt, Hasselt, Belgium
| | - Thomas Steelandt
- Laboratory of Pathological Anatomy, Jessa Hospital, Hasselt, Belgium
| | - Julie Lemahieu
- Laboratory for Dermatopathology, Dermpat, Ghent, Belgium
| | - Pieter-Jan Volders
- Laboratory for Molecular Diagnostics, Department of Clinical Biology, Jessa Hospital, Hasselt, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Ellen Geerdens
- Laboratory for Molecular Diagnostics, Department of Clinical Biology, Jessa Hospital, Hasselt, Belgium
| | - Severine Berden
- Laboratory for Molecular Diagnostics, Department of Clinical Biology, Jessa Hospital, Hasselt, Belgium
| | - Annick Daniels
- Laboratory for Molecular Diagnostics, Department of Clinical Biology, Jessa Hospital, Hasselt, Belgium
| | - Guy Froyen
- Laboratory for Molecular Diagnostics, Department of Clinical Biology, Jessa Hospital, Hasselt, Belgium
- Department Jessa & Science, LCRC (-MHU), Hasselt, Belgium
- Faculty of Medicine and Life Sciences, University of Hasselt, Hasselt, Belgium
| | - Brigitte Maes
- Laboratory for Molecular Diagnostics, Department of Clinical Biology, Jessa Hospital, Hasselt, Belgium.
- Department Jessa & Science, LCRC (-MHU), Hasselt, Belgium.
- Faculty of Medicine and Life Sciences, University of Hasselt, Hasselt, Belgium.
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Schoelinck J, Pissaloux D, Mouthon M, Vergara R, de la Fouchardière A. [Clinical, histological and genetic correlations in melanocytic tumours with chromosomal rearrangements]. Ann Pathol 2024:S0242-6498(24)00031-2. [PMID: 38320889 DOI: 10.1016/j.annpat.2024.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 01/13/2024] [Accepted: 01/16/2024] [Indexed: 02/08/2024]
Abstract
In some tumoral subtypes chromosomal translocations lead to an oncogenic chimeric protein acting as a tumorigenesis driver event. The main fusion model combines the promoter swapping of an inactivated tumor suppressor gene and a functional kinase that evades its regulatory system. The range of described fusions keeps growing in the 2023 WHO classification of melanocytic tumours. It is not limited to the group of Spitz tumours as previously but now extends to blue tumours and dermal tumours with a melanocytic phenotype. Molecular pathology helps detect these anomalies using clinical and morphological features. This analysis is essential as this strongly conditions the adapted local treatment of such tumours who are often overtreated.
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Affiliation(s)
- Jeremy Schoelinck
- Service de biopathologie, centre Léon-Bérard, 28, promenade Léa-et-Napoléon-Bullukian, Lyon, France.
| | - Daniel Pissaloux
- Service de biopathologie, centre Léon-Bérard, 28, promenade Léa-et-Napoléon-Bullukian, Lyon, France
| | - Maxime Mouthon
- Service de biopathologie, centre Léon-Bérard, 28, promenade Léa-et-Napoléon-Bullukian, Lyon, France
| | - Rémi Vergara
- Service de biopathologie, centre Léon-Bérard, 28, promenade Léa-et-Napoléon-Bullukian, Lyon, France
| | - Arnaud de la Fouchardière
- Service de biopathologie, centre Léon-Bérard, 28, promenade Léa-et-Napoléon-Bullukian, Lyon, France; Équipe labellisée Ligue contre le cancer, Inserm 1052, CNRS 5286, centre Léon-Bérard, Cancer Research Center of Lyon, université de Lyon, université Claude-Bernard Lyon 1, Lyon, France
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Takai T, Sudo T, Kajimoto K, Goto K. Reconsideration of the pathogenic significance of kinase gene fusion in melanocytic tumors based on a case of melanoma with non-in-frame BICD1::BRAF fusion. J Cutan Pathol 2023; 50:185-187. [PMID: 36335561 DOI: 10.1111/cup.14356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 11/02/2022] [Accepted: 11/03/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Toshihiro Takai
- Department of Dermatology, Hyogo Cancer Center, Akashi, Japan
| | - Tamotsu Sudo
- Section of Translational Research, Hyogo Cancer Center, Akashi, Japan.,Department of Gynecologic Oncology, Hyogo Cancer Center, Akashi, Japan
| | | | - Keisuke Goto
- Department of Dermatology, Hyogo Cancer Center, Akashi, Japan.,Department of Pathology, Tokyo Metropolitan Cancer and Infectious Disease Center Komagome Hospital, Tokyo, Japan.,Department of Pathology, Itabashi Central Clinical Laboratory, Tokyo, Japan.,Department of Diagnostic Pathology, Tokyo Medical University Hospital, Tokyo, Japan.,Department of Diagnostic Pathology, Shizuoka Cancer Center Hospital, Sunto, Japan.,Department of Diagnostic Pathology and Cytology, Osaka International Cancer Institute, Osaka, Japan.,Department of Diagnostic Pathology, Osaka National Hospital, Osaka, Japan.,Department of Dermato-Oncology/Dermatology, National Hospital Organization Kagoshima Medical Center, Kagoshima, Japan
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