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Cheng X, Wang J, Fang R, Xu J, Wang S, Zhao M. PRRX1-fused mesenchymal neoplasm: A novel PRRX1::NCOA1 fusion transcript. J Cutan Pathol 2024. [PMID: 38986510 DOI: 10.1111/cup.14683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 06/12/2024] [Accepted: 06/26/2024] [Indexed: 07/12/2024]
Abstract
PRRX1-fused mesenchymal neoplasm is a recently identified, rare subcutaneous soft tissue neoplasm that is characterized by fusion of PRRX1 (exon 1) with NCOA1 (exon 13) in the majority of reported cases. Although initially considered to be fibroblastic, a possibility of neural or neuroectodermal differentiation has been suggested in a subset of cases. We report a 26-year-old female with a 4.0 cm painless mass located in the subcutis of the left thigh. Microscopically, the tumor was well-circumscribed and multinodular and was composed of relatively monomorphic ovoid to spindle cells arranged in loose fascicles, trabeculae, and cords within alternating myxoid and fibrous matrix, and vascularized stroma. Mitotic figures were scarce and necrosis was not observed. By immunohistochemistry, the neoplastic cells demonstrated focal co-expression of S100 protein and SOX10 and were negative for epithelial membrane antigen, smooth muscle actin, desmin, CD34, STAT6, HMB45, Melan-A, and MUC4. The expression of Rb1 was retained. Targeted RNA-sequencing identified a novel transcript fusion of PRRX1 (exon 1)::NCOA1 (exon 15), which was further confirmed by reverse transcription polymerase chain reaction and Sanger sequencing. The tumor was narrowly excised and no tumor recurrence or metastasis was identified after 13 months of follow-up. In summary, we report a new case of PRRX1-fused mesenchymal neoplasm, expanding the molecular genetic spectrum and providing further support for possible neural or neuroectodermal differentiation of this emerging soft tissue tumor entity.
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Affiliation(s)
- Xiao Cheng
- Ningbo Clinical Pathology Diagnosis Center, Ningbo, China
| | - Jian Wang
- Department of Pathology, Fudan University Shanghai Cancer Center, Shanghai, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
- Institute of Pathology, Fudan University, Shanghai, China
| | - Rong Fang
- Ningbo Clinical Pathology Diagnosis Center, Ningbo, China
| | - Jiayun Xu
- Ningbo Clinical Pathology Diagnosis Center, Ningbo, China
| | - Suying Wang
- Ningbo Clinical Pathology Diagnosis Center, Ningbo, China
| | - Ming Zhao
- Ningbo Clinical Pathology Diagnosis Center, Ningbo, China
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Cordier F, Fadaei S, Ferdinande L, Dochy F, Vanwalleghem L, Van Den Bossche K, Loontiens S, Van der Meulen J, Van Roy N, Van Dorpe J, Creytens D. Revealing RB1 loss in an emerging entity: report of two cases of PRRX1-rearranged mesenchymal tumours. J Clin Pathol 2023:jcp-2023-209267. [PMID: 38154915 DOI: 10.1136/jcp-2023-209267] [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: 11/05/2023] [Accepted: 12/07/2023] [Indexed: 12/30/2023]
Abstract
AIMS PRRX1-rearranged mesenchymal tumours are a recently identified and rare subgroup of soft tissue neoplasms with distinct morphological features and genetic alterations. This study aims to further investigate the immunohistochemical profile and underlying genetic alterations in these tumours in order to get more insight on their underlying biology and the unique profile of these tumours. METHODS Two new molecular confirmed cases of PRRX1-rearranged mesenchymal tumours were thoroughly studied with immunohistochemical stainings (RB1, CD34, ALK and pan-TRK), fluorescence in situ hybridisation (FISH) RB1/13q12 and RNA-based next-generation sequencing. RESULTS Both cases exhibited typical morphological and molecular features, confirming the diagnosis of PRRX1-rearranged mesenchymal tumours. Immunohistochemistry revealed RB1 loss in both cases, which was subsequently confirmed through FISH analysis. Additionally, one case showed focal positivity for CD34, ALK and pan-TRK on immunohistochemistry. CONCLUSIONS We identified loss of RB1 in two cases of PRRX1-rearranged mesenchymal tumours. This could suggest a potential association with RB1-deficient soft tissue tumours, although further research is necessary. Furthermore, the finding of focal positivity for CD34, ALK and pan-TRK on immunohistochemistry enriches the immunohistochemical profile of these tumours.
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Affiliation(s)
- Fleur Cordier
- Department of Pathology, Ghent University Hospital,Ghent University, Ghent, Belgium
| | - Sharareh Fadaei
- Department of Pathology, Ghent University Hospital,Ghent University, Ghent, Belgium
- Department of Pathology, AZ Sint-Jan Bruges-Ostend, Bruges, Belgium
| | - Liesbeth Ferdinande
- Department of Pathology, Ghent University Hospital,Ghent University, Ghent, Belgium
| | - Frederick Dochy
- Department of Otorhinolaryngology, head and neck surgery, AZ Sint-Jan Bruges-Ostend AV, Bruges, Belgium
| | | | | | - Siebe Loontiens
- Molecular Diagnostics Ghent University Hospital (MDG), Ghent University Hospital, Ghent University, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- CRIG, Cancer Research Institute Ghent, Ghent University Hospital, Ghent University, Ghent, Belgium
| | - Joni Van der Meulen
- Molecular Diagnostics Ghent University Hospital (MDG), Ghent University Hospital, Ghent University, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- CRIG, Cancer Research Institute Ghent, Ghent University Hospital, Ghent University, Ghent, Belgium
| | - Nadine Van Roy
- Molecular Diagnostics Ghent University Hospital (MDG), Ghent University Hospital, Ghent University, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- CRIG, Cancer Research Institute Ghent, Ghent University Hospital, Ghent University, Ghent, Belgium
| | - Jo Van Dorpe
- Department of Pathology, Ghent University Hospital,Ghent University, Ghent, Belgium
- CRIG, Cancer Research Institute Ghent, Ghent University Hospital, Ghent University, Ghent, Belgium
| | - David Creytens
- Department of Pathology, Ghent University Hospital,Ghent University, Ghent, Belgium
- CRIG, Cancer Research Institute Ghent, Ghent University Hospital, Ghent University, Ghent, Belgium
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Warmke LM, Michal M, Martínek P, Agaimy A, Din NU, Perret R, Hostein I, Le Loarer F, Voltaggio L, Gross JM. "PRRX1-rearranged mesenchymal tumors": expanding the immunohistochemical profile and molecular spectrum of a recently described entity with the proposed revision of nomenclature. Virchows Arch 2023; 483:207-214. [PMID: 37338620 DOI: 10.1007/s00428-023-03575-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 05/25/2023] [Accepted: 05/30/2023] [Indexed: 06/21/2023]
Abstract
Since the publication of the 2020 World Health Organization classification of soft tissue and bone tumors, the classification of "fibroblastic" tumors has expanded to include a novel subset of tumors characterized by PRRX1::NCOA1/2 gene fusions. These tumors defy conventional classification and are morphologically distinct, characterized by a multi-nodular growth of bland spindle cells suspended in a myxo-collagenous stroma with mild cytologic atypia, "staghorn-like" vessels, and variable perivascular hyalinization. Mitotic activity is rare, and necrosis is not identified. Herein, we present six additional cases of PRRX1-rearranged mesenchymal tumors, including five cases with PRRX1::NCOA1 fusion and one case with PRRX1::KMT2D fusion. Three cases (3/6, 50%) demonstrated focal co-expression of S100 protein and SOX10, thereby expanding the immunohistochemical profile of this emerging entity. Like prior reported cases, there was no evidence of malignant behavior on short-term follow-up. The novel fusion, PRRX1::KMT2D, further expands the molecular spectrum of this entity and leads to a proposed revision of the provisional nomenclature to "PRRX1-rearranged mesenchymal tumor" to both accommodate non-NCOA1/2 fusion partners and allow for the possibility of partial neural or neuroectodermal differentiation.
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Affiliation(s)
- Laura M Warmke
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - Michael Michal
- Department of Pathology, Faculty of Medicine in Plzen, Charles University, Prague, Czech Republic
- Bioptical Laboratory, Ltd, Plzen, Czech Republic
| | | | - Abbas Agaimy
- Institute of Pathology, Friedrich-Alexander University Erlangen-Nürnberg, University Hospital, Erlangen, Germany
| | - Nasir Ud Din
- Section of Histopathology, Department of Pathology and Laboratory Medicine, Aga Khan University Hospital, Karachi, Pakistan
| | - Raul Perret
- Department of Pathology, Institut Bergonié, Bordeaux, France
| | | | - François Le Loarer
- Department of Pathology, Institut Bergonié, Bordeaux, France
- Bordeaux Institute of Oncology, BRIC U1312, INSERM, Université de Bordeaux, Institut Bergonié, 33000, Bordeaux, France
| | | | - John M Gross
- Department of Pathology, The Johns Hopkins Hospital, Baltimore, MD, USA
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