Cellular and molecular landscape of primary dermatofibrosarcoma protuberans: Insights from single-cell RNA sequencing analysis.

Dermatofibrosarcoma protuberans (DFSP) is a rare cutaneous sarcoma characterized by the COL1A1-PDGFB fusion gene. This study utilized single-cell RNA sequencing to dissect the cellular and molecular landscape of primary DFSP. Distinct DFSP cell clusters, exhibiting fibroblast-like traits, revealed variations in pathways associated with proliferation, inflammation and metabolism. Differential gene expression analysis during the differentiation from tumour stem cells to DFSP cells unveiled SMOC2, DCN and TGFBR3 as potential regulators of tumour invasion and immune infiltration through VEGF/TGF-ß signalling modulation. Cellular communication analysis highlighted interactions within DFSP cell clusters and with endothelial cells, implicating molecules such as NAMPT, ANGPT2 and PTN in pathogenesis and treatment resistance. These findings offer insights into DFSP intratumour heterogeneity, elucidate molecular mechanisms underlying tumour behaviour, and suggest potential therapeutic targets.

A cutaneous spindle cell neoplasm characterized by a COL3A1::PDGFRA fusion.

Cutaneous spindle cell neoplasms can be challenging to diagnose using routine histopathological techniques alone, and the growing repertoire of molecular studies can assist in diagnosis. We describe a cutaneous spindle cell neoplasm characterized by a COL3A1::PDGFRA rearrangement predicted to lead to constitutive activation of the PDGFRA kinase domain. The lesion shows some similarities to dermatofibrosarcoma protuberans and also benign and epithelioid fibrous histiocytomas but is distinct from these entities histopathologically and molecularly. This tumor is considered to represent an entity in the spectrum of PDGFR-driven cutaneous mesenchymal neoplasms.

Multiple primary dermatofibrosarcoma protuberans tumors in a single patient with chromosomal microarray analysis: A case report and review.

Dermatofibrosarcoma protuberans (DFSP) is a cutaneous sarcoma with a high propensity for local invasion and recurrence. Although it is a rare event, the occurrence of multiple tumors in a single patient raises a diagnostic dilemma, as metastatic disease should be differentiated from multiple primary malignant events. In more than 90% of DFSP, a pathogenic t(17;22) translocation leads to the expression of COL1A1::PDGFB fusion transcripts. Karyotype analysis, fluorescence in situ hybridization, and RT-PCR can be useful ancillary studies in detecting this characteristic rearrangement, and sequencing of the fusion transcript can be used to support a clonal origin in metastatic and multifocal disease. However, previous reports have demonstrated variable sensitivity of these assays, in part due to the high sequence variability of the COL1A1::PDGFB fusion. Here, we report a patient who developed two distinct DFSP tumors over the course of 7 years. Chromosomal microarray analysis identified distinctive genomic alterations in the two tumors, supporting the occurrence of multiple primary malignant events.

Establishment and characterization of NCC-DFSP5-C1: a novel patient-derived dermatofibrosarcoma protuberans cell line.

Dermatofibrosarcoma protuberans (DFSP) is the most prevalent dermal sarcoma, characterized by the presence of the fusion of the collagen type I alpha 1 (COL1A1) gene with the platelet-derived growth factor beta chain (PDGFB) gene. Although PDGF receptor inhibitor imatinib mesylate was approved for the treating patients with unresectable or metastatic DFSP, disease progression was shown in 9.2% of the patients. Therefore, developing novel therapeutic strategies is crucial for improving the prognosis of DFSP. Patient-derived cell lines play a vital role in preclinical studies; however, only a limited number of DFSP cell lines are currently available in public cell banks. Here, we successfully established a novel DFSP cell line (NCC-DFSP5-C1) using surgically resected tumor tissue from a patient with DFSP. NCC-DFSP5-C1 cells were confirmed to carry the COL1A1-PDGFB translocation and maintain the same mutation as the original tumor tissue. They exhibited consistent growth, formed spheroids, and were invasive. By screening a drug library using NCC-DFSP5-C1 and four previously established DFSP cell lines, we identified anti-cancer drugs that inhibit DFSP cell proliferation. Our observations suggest that the NCC-DFSP5-C1 cell line holds promise as a valuable tool for conducting fundamental and preclinical studies for DFSP.

COL1A1::PDGFB fusion-associated uterine fibrosarcoma: A case report and review of the literature.

BACKGROUND: Mesenchymal neoplasms of the uterus encompass a diverse group of tumors, with varying characteristics and origins, collectively accounting for 8% of uterine malignancies. The most common variants include uterine leiomyosarcoma, low-grade and high-grade endometrial stromal sarcoma, adenosarcoma, and undifferentiated sarcoma. Clinical presentation is often nonspecific and can lead to delayed diagnosis. Uterine sarcomas are generally aggressive, resulting in poorer prognosis compared to carcinomas. Recent advances in molecular techniques, such as next-generation sequencing (NGS), have led to the identification of new subtypes of uterine sarcomas, including COL1A1::PDGFB fusion-associated fibrosarcoma, which has a specific chromosomal translocation t(17;22)(q22;q13). Imatinib, a tyrosine kinase inhibitor (TKI), is an effective treatment for dermatofibrosarcoma protuberans (DFSP), marked by this translocation. CASE: We present the case of a 42-year-old woman diagnosed with COL1A1::PDGFB fusion-associated uterine fibrosarcoma. The patient underwent total hysterectomy and excision of the tumor, initially misdiagnosed as a low-grade leiomyosarcoma. Subsequent histological examination, immunohistochemistry, and fluorescence in situ hybridization (FISH) confirmed the diagnosis. After 10 months, disease recurrence was detected, and Imatinib therapy was initiated at a dose of 400 mg daily. An allergic reaction led to a temporary discontinuation, but upon resumption with appropriate medication, a positive radiological response was observed. The patient achieved a complete remission after 2 years and is still on Imatinib treatment. CONCLUSIONS: COL1A1::PDGFB fusion-associated uterine fibrosarcoma is an extremely rare mesenchymal neoplasm. In a case we present herein, we treated a patient with imatinib as first-line medical therapy. The patient is currently in complete remission after 37 months from treatment start. To the best of our knowledge, this represents a unique observation. We also provide a detailed literature review of the published cases so far. Prospective case series are needed to further understand the natural history of these tumors and optimize treatment strategies.

COL1A1::PDGFB fusion uterine sarcoma with a TERT promoter mutation.

COL1A1::PDGFB fusion uterine sarcoma is a rare uterine mesenchymal tumor with some clinicopathological features that overlap with those of soft tissue dermatofibrosarcoma protuberans. However, the varied clinicopathologic and genetic characteristics have not been fully revealed, which may be a potential pitfall for diagnosis. Here, we present a case of COL1A1::PDGFB fusion-positive uterine sarcoma in a 49-years-old female. Histologically, the tumor from the initial marginal excision predominantly exhibited high-grade fibrosarcomatous and myxofibrosarcoma-like appearances, while a low-grade focal area displaying storiform growth was identified in the residual tumor after subsequently extended resection. Immunohistochemically, the high-grade components mainly exhibited focal positivity for CD34 and mutated-type p53 immunoreactivity, whereas the low-grade component showed diffuse positivity for CD34 and wild-type p53 staining. The COL1A1::PDGFB fusion was confirmed by fluorescence in situ hybridization and next-generation sequencing. In addition, the TERT-124 C > T mutation was further identified in this lesion's fibrosarcomatous and classic storiform components. To the best of our knowledge, this is the first described case of COL1A1::PDGFB fusion uterine sarcoma with a TERT promoter mutation, which might be a novel genetic finding associated with tumorigenesis of this rare tumor.

Novel role of fluorescent in situ hybridization technique (FISH) in recommended surgical margins of dermatofibrosarcoma protuberans: A preliminary study.

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is a rare skin tumor. There is no standard recommendation for its surgical management. The currently used histological analysis are HES (hematoxylin eosin saffron) staining and immunohistochemistry for CD34 expression in particular cases. Fluorescent in situ hybridization (FISH) technique is only used to qualify the DFSP as translocated or non-translocated and is not used as a diagnostic method. The aim of our study was to determine by FISH (as a diagnostic method) whether cancerous cells that could not be identified through HES staining±immunohistochemistry were present at the two-centimeter margins that were found to be tumor-free. METHODS: Samples from patients who underwent surgery between 2010 and 2018 were collected. Intralesional and peripheral (at 2cm margins) paraffin slides were included. An average of 7.4 slides per specimen was analyzed. Firstly, the preselected slides were reread by a senior pathologist to confirm the absence of microscopic findings of DFSP at 2cm margins. Secondly a FISH analysis was used as a quantitative diagnostic approach, in order to find the t(17;22) translocation. RESULTS: Among the seven specimens that included 2cm margins, two samples presented one or more translocations, which were not visible in standard morphology assessments at two centimeters tumor-free margins. CONCLUSIONS: FISH analysis can have a new role in defining tumor-free margins. This would reduce the incidence of disease recurrence after resection and improve the post-operative complementary care.

Unraveling intratumoral complexity in metastatic dermatofibrosarcoma protuberans through single-cell RNA sequencing analysis.

Dermatofibrosarcoma protuberans (DFSP) stands as a rare and locally aggressive soft tissue tumor, characterized by intricated molecular alterations. The imperative to unravel the complexities of intratumor heterogeneity underscores effective clinical management. Herein, we harnessed single-cell RNA sequencing (scRNA-seq) to conduct a comprehensive analysis encompassing samples from primary sites, satellite foci, and lymph node metastases. Rigorous preprocessing of raw scRNA-seq data ensued, and employing t-distributed stochastic neighbor embedding (tSNE) analysis, we unveiled seven major cell populations and fifteen distinct subpopulations. Malignant cell subpopulations were delineated using infercnv for copy number variation calculations. Functional and metabolic variations of diverse malignant cell populations across samples were deciphered utilizing GSVA and the scMetabolism R packages. Additionally, the exploration of differentiation trajectories within diverse fibroblast subpopulations was orchestrated through pseudotime trajectory analyses employing CytoTRACE and Monocle2, and further bolstered by GO analyses to elucidate the functional disparities across distinct differentiation states. In parallel, we segmented the cellular components of the immune microenvironment and verified the presence of SPP1+ macrophage, which constituted the major constituent in lymph node metastases. Remarkably, the CellChat facilitated a comprehensive intercellular communication analysis. This study culminates in an all-encompassing single-cell transcriptome atlas, propounding novel insights into the multifaceted nature of intratumor heterogeneity and fundamental molecular mechanisms propelling metastatic DFSP.

COL1A1-PDGFB Fusion Gene Detection Through Bulk RNA-Seq and Transcriptomic Features of Dermatofibrosarcoma Protuberans.

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is a cutaneous sarcoma with obscure origin and multidirectional differentiation. Application of RNA-Seq in the detection of COL1A1-PDGFB is still at early stages. OBJECTIVE: We aim to test the efficacy of fusion gene detection using bulk RNA-Seq in DFSPs, explore altered molecular pathways and biological processes for evidences of tumor origin and cell identity shift. MATERIALS AND METHODS: Dermatofibrosarcoma protuberans and normal dermis samples were acquired for RNA-Seq. Fusion gene detection was performed using STAR-Fusion. RNA-Seq 2G yielded differentially expressed genes. Altered pathways, key gene ontology terms, and similar cell/tissue types were identified with gene set enrichment analysis. xCell was used for cell types enrichment analysis. RESULTS: 28/30 CD34(+) cases were positive for COL1A1-PDGFB. 406 upregulated and 543 downregulated genes were determined. Among the top 10 upregulated genes, 6 had neural distribution, function, or disease correlation. The upregulated genes were related to synapse, trans-synaptic signaling, neural development, and extracellular matrix. Similarities between DFSP and nervous system components were highlighted, with fibroblast cellular abundancy increased during xCell analysis. CONCLUSION: Bulk RNA-Seq provided with high detection rate of COL1A1-PDGFB. Dermatofibrosarcoma protuberans showed fibroblastic activity and neural features, which validated DFSP's fibroblast origin and tendency of neural differentiation.

Platelet-Derived Growth Factor-D Fusion-Positive Dermatofibrosarcoma Protuberans: Case Report of an Atypical Breast Mass and Literature Review.

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.

[Cryptic COL1A1-PDGFB fusion in dermatofibrosarcoma protuberans: a clinicopathological and genetic analysis].

Objective: To investigate the clinicopathological and cytogenetic features of cryptic COL1A1-PDGFB fusion dermatofibrosarcoma protuberans (CC-DFSP). Methods: Three cases of CC-DFSP diagnosed in West China Hospital, Sichuan University, Chengdu, China from January 2021 to September 2021 were studied. Immunohistochemistry for CD34 and other markers, fluorescence in situ hybridization (FISH) for PDGFB, COL1A1-PDGFB and COL1A1, next-generation sequencing (NGS), reverse-transcriptase polymerase chain reaction (RT-PCR) and Sanger sequencing were performed. Results: There were three cases of CC-DFSP, including two females and one male. The patients were 29, 44 and 32 years old, respectively. The sites were abdominal wall, caruncle and scapula. Microscopically, they were poorly circumscribed. The spindle cells of the tumors infiltrated into the whole dermis or subcutaneous tissues, typically arranging in a storiform pattern. Immunohistochemically, the neoplastic cells exhibited diffuse CD34 expression, but were negative for S-100, SMA, and Myogenin. Loss of H3K27me3 was not observed in the tumor cells. The Ki-67 index was 10%-15%. The 3 cases were all negative for PDGFB rearrangement and COL1A1-PDGFB fusion, whereas showing unbalanced rearrangement for COL1A1. Case 1 showed a COL1A1 (exon 31)-PDGFB (exon 2) fusion using NGS, which was further validated through RT-PCR and Sanger sequencing. All patients underwent extended surgical resection. Except for case 3 with recurrence 2 years after surgical resection, the other 2 cases showed no recurrence or metastasis during the follow-up. Conclusions: FISH has shown its validity for detecting PDGFB rearrangement and COL1A1-PDGFB fusion and widely applied in clinical detection. However, for cases with negative routine FISH screening that were highly suspicious for DFSPs, supplementary NGS or at least COL1A1 break-apart FISH screening could be helpful to identify cryptic COL1A1-PDGFB fusions or other variant fusions.

Review of dermatofibrosarcoma protuberans.

The clinical features, histological subtypes and management of dermatofibrosarcoma protuberans (DFSP) are reviewed in this article. DFSP is an uncommon cutaneous sarcoma first described in 1890. It has a high local recurrence rate, low metastatic rate and low mortality. The crude incidence rate in England in 2019 was reported as 3.0 per million person-years. A fusion of platelet-derived growth factor subunit B (PDGFB) and COL1A1, t(17;22)(q22;q13), has been found in over 90% of people with DFSP. This fusion is thought to upregulate PDGFB expression, stimulating cell growth by activation of Ras mitogen-activated protein kinases and PI3K-AKT-mTOR, potentiating oncogenesis. DFSP usually presents as an asymptomatic flesh-coloured, thickened, rubbery plaque or nodule with an uneven surface. The most common sites are the trunk followed by lower limbs, head and neck and upper limbs. Larger tumours can infiltrate underlying local structures and around 1% metastasize. Key histological features in DFSP are spindle cells arranged in a storiform pattern with intense CD34 staining. Histological subtypes include classical DFSP, Bednar, myxoid, giant cell fibroblastoma, atrophic and DFSP-fibrosarcomatous. The gold standard management for localized tumours is surgical: current recommendations favour Mohs micrographic surgery over wide local excision. Adjuvant radiotherapy may be offered after surgery. Imatinib can be used as neoadjuvant therapy and in patients with inoperable or metastatic tumours. Further research should be conducted to better understand pathogenesis of DFSP, identify associated risk factors and standardize management.

A Case of COL1A1-PDGFB Fusion Uterine Sarcoma.

COL1A1-PDGFB gene fusion uterine sarcoma is a recently described entity which shows some overlapping features with dermatofibrosarcoma protuberans. To date, only 4 cases have been reported in the literature. Due to its rarity, succinct clinicopathologic characteristics are yet to be established. We report a fifth case initially mistaken as a uterine fibroid which histologically proved to be a CD34 + high-grade spindle cell proliferation which on fluorescence in situ hybridization analysis displayed COL1A1-PDGFB gene rearrangement. With this case description we hope to raise awareness and aid in the characterization of this emerging entity.

Dermatofibrosarcoma protuberans of the face: A clinicopathologic and molecular study of 34 cases.

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is one of the most common dermal sarcomas, but facial DFSP is rare. PATIENTS AND METHODS: The clinicopathological characteristics of 34 facial DFSPs were reviewed. Additional immunostaining (CD34) and PDGFB/COL1A1-PDGFB fluorescence in situ hybridization (FISH) detection were performed. RESULTS: Patients were aged from 24 to 64 years (mean 42.9 years), with a male-to-female ratio of 4.7 : 1. Morphologically, classic DFSP (25/34, 73.5 %), pigmented DFSP (2/34, 5.9 %), DFSP with myoid differentiation (1/34, 2.9 %) and fibrosarcomatous DFSP (FS-DFSP) (6/34, 17.6 %) were found. Moreover, myxoid degeneration was observed in three FS-DFSP cases (3/6, 50.0 %). All 29 cases that underwent CD34 immunohistochemistry exhibited positive staining (100 %). Genetically, PDGFB rearrangement/COL1A1-PDGFB fusion was detected in 94.1 % (16/17) of patients. Regarding prognosis, the recurrence (83.3 % vs. 59.1 %) and metastasis (33.3 % vs. 0 %) rates were higher in FS-DFSPs than that in ordinary DFSPs. All available surgical margins were positive before DFSPs recurrence. All patients with negative excision or re-excision margins were alive without evidence of disease (mean, 81.8 months; median, 81 months). CONCLUSIONS: Facial DFSP occurs predominantly in males, while FS-DFSPs are more likely to exhibit myxoid degeneration and a worse prognosis. Notably, negative surgical margin status determined a satisfactory prognosis.

Giant cell fibroblastoma: a case report.

Giant cell fibroblastoma is a rare locally aggressive tumor of subcutaneous mesenchymal tissue, occurring mostly on the trunk in young individuals with maximal incidence in the first decade of life. Local recurrences of giant cell fibroblastoma are common if marginally excised, however, distant metastases do not occur. Giant cell fibroblastoma was labelled as a juvenile variant of dermatofibrosarcoma protuberans (DFSP) due to quite frequent combination of both lesions, morphological similarities, identical immunoprofile, and shared gene fusion t(17;22) COL1A1-PDGFB. In this paper, we report a case of a young man with a slowly growing subcutaneous tumor in the groin. The tumor was excised and histological examination identified a mesenchymal tumor with variable cellularity, presence of multinucleated giant cells and pleomorphic spindle cells, which lined pseudovascular or angiectoid spaces. The CD34 immunohistochemistry showed strong positivity in all of these cells, whereas ERG was positive only in endothelial cells in true vessels. These findings led to a suspicion on giant cell fibroblastoma. Because of its borderline malignant behaviour and positive surgical margins, the lesion was subsequently reexcised. The molecular analysis identified the transcription product of gene fusion COL1A1-PDGFB and thus, final diagnosis was confirmed. The article includes review of the literature and brief historical overview of giant cell fibroblastoma concept as an unique entity.

Identification of Potential Drug Therapy for Dermatofibrosarcoma Protuberans with Bioinformatics and Deep Learning Technology.

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is a rare mesenchymal tumor that is primarily treated with surgery. Targeted therapy is a promising approach to help reduce the high rate of recurrence. This study aims to identify the potential target genes and explore the candidate drugs acting on them effectively with computational methods. METHODS: Identification of genes associated with DFSP was conducted using the text mining tool pubmed2ensembl. Further gene screening was carried out by conducting Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Protein-Protein Interaction (PPI) network was constructed by using the Search Tools for the Retrieval of Interacting (STRING) database and visualized in Cytoscape. The gene candidates were identified after a literature review. Drugs targeting these genes were selected from Pharmaprojects. The binding affinity scores of Drug-Target Interaction (DTI) were predicted by a deep learning algorithm Deep Purpose. RESULTS: A total of 121 genes were found to be associated with DFSP by text mining. The top 3 statistically functionally enriched pathways of GO and KEGG analysis included 36 genes, and 18 hub genes were further screened out by constructing a PPI networking and literature retrieval. A total of 42 candidate drugs targeted at hub genes were found by Pharmaprojects under our restrictions. Finally, 10 drugs with top affinity scores were predicted by DeepPurpose, including 3 platelet-derived growth factor receptor beta kinase (PDGFRB) inhibitors, 2 platelet-derived growth factor receptor alpha kinase (PDGFRA) inhibitors, 2 Erb-B2 receptor tyrosine kinase 2 (ErbB-2) inhibitors, 1 tumor protein p53 (TP53) stimulant, 1 vascular endothelial growth factor receptor (VEGFR) antagonist, and 1 prostaglandin-endoperoxide synthase 2 (PTGS2) inhibitor. CONCLUSION: Text mining and bioinformatics are useful methods for gene identification in drug discovery. DeepPurpose is an efficient and operative deep learning tool for predicting the DTI and selecting the drug candidates.