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Yeung MCF, Fong T, Liu APY, Chan RCK, Chan AZ, Lau WH, Lok J, Gao GY, Leung SY, Shek TWH. Comprehensive Clinicopathological and Multiomics Characterization of Dermatofibrosarcoma Protuberans Revealed PDGFD Fusion as Distinct Molecular Subtype With Better Survival. Mod Pathol 2025; 38:100792. [PMID: 40348059 DOI: 10.1016/j.modpat.2025.100792] [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: 02/28/2025] [Revised: 04/13/2025] [Accepted: 04/28/2025] [Indexed: 05/14/2025]
Abstract
Dermatofibrosarcoma protuberans (DFSP) is a locally aggressive superficial mesenchymal neoplasm characterized by COL1A1::PDGFB fusion. Recently, PDGFD has been identified as a less common fusion partner. However, the clinicopathological and molecular differences between PDGFD-fusion and PDGFB-fusion DFSP remain largely unknown. In this study of 363 DFSP, we found 10 cases with PDGFD fusion, including 2 with a previously undescribed partner involving the EMILIN1 gene. Multiomics analysis showed distinct transcriptomics, epigenomics, and copy number features for PDGFD-fusion DFSP versus PDGFB-fusion DFSP. PDGFD-fusion DFSP had higher PDGFD expression and virtually no PDGFB expression. Both clustered into the DFSP epigenomic cluster but formed a distinct subcluster with differential methylation affecting fibroblast migration genes. Copy number analysis revealed that PDGFD-fusion DFSP formed a distinct subgroup with a generally copy number-neutral profile and better survival than PDGFB-fusion DFSP that was dominated by amplification at translocation sites in chromosomes 17 and 22. Pooled analysis of 39 cases (incorporating 29 from the literature) revealed that PDGFD-fusion DFSP was more common in women (71.8% vs 42.4%, P < .001), occurred at a lower age (median, 37 years vs 45 years, P < .01), and had a higher chance of occurrence at the breast (25.6% vs 2.3%, P < .001). PDGFD-fusion DFSP also tended to center predominantly in the subcutis (63.6% vs 30%, P < .001), had a circumscribed border (50% vs 19.2%, P < .001), was smaller in size (3 cm vs 3.5 cm, P = .017), and had a lower mitotic count (median, 1 vs 3 per 10 high-power fields, P = .03). Overall, our study provided detailed multiomics characterization of PDGFD-fusion DFSP with significant clinicopathological and diagnostic implications.
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Affiliation(s)
- Maximus C F Yeung
- Department of Pathology, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong Kong SAR, China.
| | - Tsun Fong
- Department of Pathology, Princess Margaret Hospital, Hong Kong SAR, China
| | - Anthony P Y Liu
- Department of Paediatrics and Adolescent Medicine, School of Clinical Medicine, The University of Hong Kong, Hong Kong SAR, China; Department of Paediatrics and Adolescent Medicine, Hong Kong Children's Hospital, Hong Kong SAR, China; Division of Haematology and Oncology, The Hospital for Sick Children, Toronto, Canada
| | - Ronald C K Chan
- Department of Pathology, North District Hospital, Hong Kong SAR, China
| | - Angela Z Chan
- Department of Anatomical and Cellular Pathology, Prince of Wales Hospital, Hong Kong SAR, China
| | - W H Lau
- Department of Pathology, Kwong Wah Hospital, Hong Kong SAR, China
| | - Johann Lok
- Department of Pathology, United Christian Hospital, Hong Kong SAR, China
| | - Gloria Y Gao
- Department of Pathology, Caritas Medical Centre, Hong Kong SAR, China
| | - S Y Leung
- Department of Pathology, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong Kong SAR, China; The Jockey Club Centre for Clinical Innovation and Discovery, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China; Centre for PanorOmic Sciences, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Tony W H Shek
- Department of Pathology, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong Kong SAR, China
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Kalmykova AV, Baranovska-Andrigo V, Michal M. Update on cutaneous mesenchymal tumors in the 5th edition of WHO classification of skin tumors with an emphasis on new fusion-associated neoplasms. Virchows Arch 2024; 485:777-792. [PMID: 39264472 PMCID: PMC11564315 DOI: 10.1007/s00428-024-03925-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2024] [Revised: 08/27/2024] [Accepted: 08/31/2024] [Indexed: 09/13/2024]
Abstract
The section on mesenchymal tumors in the 5th edition of WHO classification of skin tumors has undergone several changes, the most important of which is the inclusion of newly identified tumor entities, which will be the main focus of this review article. These specifically include three novel cutaneous mesenchymal tumors with melanocytic differentiation, and rearrangements of the CRTC1::TRIM11, ACTIN::MITF, and MITF::CREM genes as well as EWSR1::SMAD3-rearranged fibroblastic tumors, superficial CD34-positive fibroblastic tumors, and NTRK-rearranged spindle cell neoplasms. Some of the other most important changes will be briefly mentioned as well.
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Affiliation(s)
- Antonina V Kalmykova
- Medical Laboratory CSD, Ltd., Kiev, Ukraine
- Department of Pathology, Charles University, Faculty of Medicine in Plzen, Medical Faculty and Charles University Hospital Plzen, Alej Svobody 80, 323 00, Plzen, Czech Republic
| | - Vira Baranovska-Andrigo
- Department of Pathology, Charles University, Faculty of Medicine in Plzen, Medical Faculty and Charles University Hospital Plzen, Alej Svobody 80, 323 00, Plzen, Czech Republic
| | - Michael Michal
- Department of Pathology, Charles University, Faculty of Medicine in Plzen, Medical Faculty and Charles University Hospital Plzen, Alej Svobody 80, 323 00, Plzen, Czech Republic.
- Bioptical Laboratory, Ltd., Pilsen, Czech Republic.
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Bourgeau M, Gardner JM. Immunohistochemistry Update in Dermatopathology and Bone and Soft Tissue Pathology. Arch Pathol Lab Med 2024; 148:284-291. [PMID: 37535665 DOI: 10.5858/arpa.2023-0033-ra] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/30/2023] [Indexed: 08/05/2023]
Abstract
CONTEXT.— Immunohistochemistry plays an important role in dermatopathology, particularly for melanocytic lesions and poorly differentiated malignancies. In the field of bone and soft tissue pathology, molecular methods remain the gold standard for diagnosis; however, immunohistochemistry targeting underlying molecular alterations represents a valuable screening tool, especially in areas with limited access to molecular testing. OBJECTIVE.— To describe the utility and limitations of new and emerging immunohistochemical stains in the diagnosis of skin, soft tissue, and bone tumors. DATA SOURCES.— A literature review of recently described immunohistochemical stains in the fields of dermatopathology and bone and soft tissue pathology was performed. CONCLUSIONS.— Immunohistochemistry is an important adjunctive tool for select entities in dermatopathology and bone and soft tissue pathology, and it provides pathologists with valuable evidence of their behavior, underlying molecular alterations, and line of differentiation. Furthermore, immunostains targeting molecular abnormalities have the potential to replace current molecular methods. Many of these recently described stains demonstrate higher sensitivity and specificity; however, limitations and pitfalls still exist, and correlation with morphologic and clinical findings remains essential for diagnosis.
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Affiliation(s)
- Melanie Bourgeau
- the Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia (Bourgeau)
| | - Jerad M Gardner
- From the Department of Laboratory Medicine, Geisinger Medical Center, Danville, Pennsylvania (Gardner)
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Yeung MC, Dermawan JK, Liu AP, Lam AY, Antonescu CR, Shek TW. Spindle cell neoplasms with novel LTK fusion - Expanding the spectrum of kinase fusion-positive soft tissue tumors. Genes Chromosomes Cancer 2024; 63:e23227. [PMID: 38517106 PMCID: PMC10963038 DOI: 10.1002/gcc.23227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/09/2024] [Accepted: 01/24/2024] [Indexed: 03/23/2024] Open
Abstract
AIMS Kinase fusion-positive soft tissue tumors represent an emerging, molecularly defined group of mesenchymal tumors with a wide morphologic spectrum and diverse activating kinases. Here, we present two cases of soft tissue tumors with novel LTK fusions. METHODS AND RESULTS Both cases presented as acral skin nodules (big toe and middle finger) in pediatric patients (17-year-old girl and 2-year-old boy). The tumors measured 2 and 3 cm in greatest dimension. Histologically, both cases exhibited bland-looking spindle cells infiltrating adipose tissue and accompanied by collagenous stroma. One case additionally displayed perivascular hyalinization and band-like stromal collagen. Both cases exhibited focal S100 staining, and one case had patchy coexpression of CD34. Targeted RNA-seq revealed the presence of novel in-frame MYH9::LTK and MYH10::LTK fusions, resulting in upregulation of LTK expression. Of interest, DNA methylation-based unsupervised clustering analysis in one case showed that the tumor clustered with dermatofibrosarcoma protuberans (DFSP). One tumor was excised with amputation with no local recurrence or distant metastasis at 18-month follow-up. The other case was initially marginally excised with local recurrence after one year, followed by wide local excision, with no evidence of disease at 10 years of follow-up. CONCLUSIONS This is the first reported case series of soft tissue tumors harboring LTK fusion, expanding the molecular landscape of soft tissue tumors driven by activating kinase fusions. Furthermore, studies involving a larger number of cases and integrated genomic analyses will be warranted to fully elucidate the pathogenesis and classification of these tumors.
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Affiliation(s)
- Maximus C.F. Yeung
- Department of Pathology, School of Clinical Medicine, The University of Hong Kong, Hong Kong
| | - Josephine K Dermawan
- Robert J. Tomsich Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Anthony P.Y. Liu
- Department of Paediatrics and Adolescent Medicine, School of Clinical Medicine, The University of Hong Kong, Hong Kong
- Department of Paediatrics and Adolescent Medicine, Hong Kong Children’s Hospital, Hong Kong
| | - Albert Y.L. Lam
- Division of General Orthopaedics and Oncology, Department of Orthopedics and Traumatology, School of Clinical Medicine, The University of Hong Kong, Hong Kong
| | - Cristina R Antonescu
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Tony W.H. Shek
- Department of Pathology, School of Clinical Medicine, The University of Hong Kong, Hong Kong
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Chandler B, Jing F, David MP, Nazarullah A. Platelet-Derived Growth Factor-D Fusion-Positive Dermatofibrosarcoma Protuberans: Case Report of an Atypical Breast Mass and Literature Review. Int J Surg Pathol 2023; 31:1610-1617. [PMID: 37016743 DOI: 10.1177/10668969231160261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2023]
Abstract
Dermatofibrosarcoma protuberans (DFSP) is a rare, CD34+ mesenchymal neoplasm that classically involves the dermis. A COL1A1::PDGFB t(17;22) translocation is present in 91.4% to 96% of cases, resulting in aberrant proliferation due to tyrosine kinase hyperactivity. Here, we present a postmenopausal woman with a CD34-positive spindle cell neoplasm of the breast without cutaneous involvement, lacking muscle marker expression, STAT6 expression, and 13q14 deletion by fluorescence in situ hybridization (FISH). Although the classic PDGFB translocation was not detected by FISH, the overall features were highly suspicious for DFSP. Subsequent RNA-based next-generation sequencing revealed an EMILIN2::PDGFD fusion. A literature review showed that PDGFD fusions can be detected in up to 55% PDGFB FISH negative cases, with EMILIN2::PDGFD fusion highly associated with fibrosarcomatous transformation. This holds important diagnostic and prognostic information as fibrosarcomatous-DFSP is associated with higher recurrence and metastatic potential. The tumor was completely resected with clear margins, showed no fibrosarcomatous areas, and no evidence of recurrence is documented 2 years since resection. This review and case report adds to the literature regarding PDGFD-translocation positive DFSP as a differential diagnosis of CD34-positive spindle cell tumors of the breast, while emphasizing the prognostic importance of EMILIN2::PDGFD fusions.
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Affiliation(s)
- Blake Chandler
- University of Texas Health Long School of Medicine, San Antonio, TX, USA
| | - Frank Jing
- University of Texas Health Long School of Medicine, San Antonio, TX, USA
| | - Marjorie Parker David
- Department of Pathology and Laboratory Medicine, University of Texas Health, San Antonio, TX, USA
| | - Alia Nazarullah
- Department of Pathology and Laboratory Medicine, University of Texas Health, San Antonio, TX, USA
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Legrand M, Tallegas M, Coeugnet A, Macagno N, Jullié ML, Kervarrec T. Superficial spindle cell tumour with TNC::PDGFD fusion is a distinct entity from dermatofibrosarcoma protuberans. Pathology 2022; 55:562-564. [PMID: 36351867 DOI: 10.1016/j.pathol.2022.08.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 08/05/2022] [Indexed: 11/05/2022]
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