Metastatic Dermatofibrosarcoma Protuberans Research Articles

A case report of abdominal metastatic dermatofibrosarcoma protuberans misdiagnosed as gastrointestinal stromal tumor

Dermatofibrosarcoma protuberans (DFSP) is a low-grade malignant soft-tissue tumor that originates from the skin. It has a slow onset in the early stages, non-specific clinical symptoms, low specificity, and can easily be overlooked, missed, or misdiagnosed by clinicians and pathologists. In addition, DFSP is prone to recurrence after local surgical treatment; however, distant metastasis, especially abdominal metastasis, is rare, which is also a challenge for the accurate diagnosis of DFSP when it progresses distantly. Now a case of abdominal metastasis of DFSP is reported. The patient has been treated with imatinib for ten years, and the lesion has shrunk, but because the patient has been receiving imatinib treatment, his abdominal lesion was once misdiagnosed as gastrointestinal stromal tumor. Therefore, we report on this case to enhance the understanding of the diagnosis and treatment of DFSP, and to provide reference for the pathological diagnosis and precise treatment of such patients.

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.

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.

Multi-omic profiling and real time ex vivo modelling of imatinib-resistant dermatofibrosarcoma protuberans with fibrosarcomatous transformation.

Dermatofibrosarcoma protuberans (DFSP) is a rare and indolent cutaneous sarcoma, with the risk of aggressive fibro-sarcomatous transformation. Limited effective options are available for un-resectable or metastatic DFSP beyond targeting the oncogenic PDGF pathway with imatinib therapy. We established a patient-derived xenograft (PDX) and cell line model (designated MDFSP-S1) of imatinib-resistant DFSP with fibro-sarcomatous transformation. Whole genome sequencing identified high-level amplification at chromosomes 17 and 22, whilst homozygous deep deletion was demonstrated at chromosome 9 (CDKN2A, CDKN2B, MTAP). RNA sequencing followed by Sanger sequencing confirmed the pathognomonic COL1A1-PDGFB t (17;22) rearrangement in the original tumour, PDX and cell line model. Immunohistochemistry profiles of the PDX model were consistent with the patient's tumour sample (CD34 + /MIB1 + /SOX10- ). Gene set enrichment analysis highlighted top-scoring Hallmark gene sets in several oncogenic signalling pathways, including potentially targetable MTORC1 signalling and angiogenesis pathways. Antiangiogenic agents (sunitinib, regorafenib, pazopanib, axitinib) and the third-generation irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor osimertinib exhibited modest anti-proliferative activity in the cell line, with IC50 values between 1 and 10µM at 72h. No significant activity was observed with imatinib, palbociclib, everolimus, olaparib, gefitinib and erlotinib (IC50 all > 10µM). In conclusion, we established MDFSP-S1, a new PDX and cell line model of imatinib-resistant DFSP with fibro-sarcomatous transformation.

The Role of Imatinib Mesylate in the Treatment of Metastatic Dermatofibrosarcoma Protuberans: A Case Report and Literature Review

Dermatofibrosarcoma of Darier and Ferrand is a rare cutaneous tumor characterized by its local aggressiveness and high potential for recurrence. It rarely metastasizes, but when it does, the prognosis is poor. Surgery plays a crucial role in the management of these tumors, while targeted therapy is beneficial for metastatic or unresectable forms. Here, we present the case of a 50-year-old female patient who was admitted to our hospital for the management of metastatic dermatofibrosarcoma in the liver. The patient underwent wide excision surgery followed by treatment with imatinib. One-year follow-up showed a good response.

Oncological efficiency of wide local excision in dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is a slow-growing, low- to intermediate-grade malignant sarcoma. Its optimal treatment is resection with wide margins; the likelihood of local control associated with this procedure exceeds 90%. The probability of regional or distant metastases is <5%. We examined the clinical, epidemiological, and pathological features, the treatment types, and outcomes of patients to investigate the width of safe surgical margins (SM) and how the width of SMs affected recurrence in DFSP. We retrospectively examined the records of 60 patients who were initially operated on with wide local excision for DFSP in the period 2008-2019. Optimal cutoff points for SMs were calculated with the receiver operating characteristic curve analysis and found as 1.925cm histopathologically and 2.26cm macroscopically. During the mean 89.6-month follow-up, local recurrence was seen in 36.7% and distant metastasis in 20% of the patients. Recurrences were significantly related to peripheral resection margins. Analysis by histopathologic cutoff points showed that the local recurrence rate was 84% when SM was ≤1.925cm, but only 2.85% when >1.925cm (p=0.002). Recurrence-free survival was 40.92 months when SM was ≤1.925cm and 225.75 months when s >1.925cm (p<0.001). Analysis by macroscopic cutoff points showed that the local recurrence rate was 95.5% when SM was ≤2.26cm, but only 4% when >2.26cm (p=0.001). Recurrence-free survival was 43 months when SM was ≤2.26cm and 222 months when >2.26cm (p<0.001). In metastatic patients, progression-free survival was 9 months with cytotoxic chemotherapy, whereas 38.4 months with tyrosine kinase inhibitor (imatinib) (p=0.002). This study showed SMs >2.5cm to be sufficiently safe for WLE and optimized the balance among safe margin width, reconstruction need, and surgical morbidity. In metastatic DFSP patients, tyrosine kinase inhibitor imatinib is more effective than cytotoxic chemotherapy for progression-free survival.

The varied presentation of dermatofibrosarcoma protuberans: a case series of 9 patients treated in single institute

&lt;p class="abstract"&gt;Dermatofibrosarcoma protuberans (DFSP) is a rare skin tumor with an estimated incidence of 0.8 to five cases per 1 million people per year. To our surprise, we’d encountered total 9 cases of DFSP with different presentation in our hospital from November 2009-July 2019. One patient with underlying DFSP presented with intraperitoneal bleeding tumor while another 8 patients were newly diagnosed. The mean patient age at the time of diagnosis were 38.4 years. Sex distribution were male in predominance. The anatomical location of tumor varied. Majority presented clinically with slow growing mass on skin/subcutaneous tissue, one tumor grew on a preceding scar, and 2 patients came with bleeding tumors. The median follow-up duration in this series was 23.6 months. Wide local excision was performed in 6 patients, with half of them reported to have surgical margins involved. Reconstruction of the surgical defect took place primarily in 4 patients and split skin graft in 2 patients. Adjuvant radiotherapy was offered to 3 patients with surgical margin involved and disease recurrence. Imatinib was given to one patient with metastatic DFSP prior definitive surgery which was successful. There were no local recurrence or death due to the DFSP course at the end of the follow-up. Final outcome was favorable. Hereby we present the 9 interesting case series.&lt;/p&gt;

Advanced dermatofibrosarcoma protuberans: an updated analysis of cases from an Indian sarcoma clinic.

Aim:Dermatofibrosarcoma protuberans (DFSP) accounts for less than 2% of all soft-tissue sarcomas.Patients & methods:We retrospectively reviewed our database for patients with locally advanced or metastatic DFSP who had presented to our clinic between January 2016 and January 2020.Results:We identified a total of 14 patients, of whom ten had sarcomatous transformation. Eleven cases had metastatic disease and three were locally advanced. The initial partial response rate to first-line imatinib was 76.9% and the overall median progression-free survival on imatinib was 15 months.Conclusion:We had a high proportion of patients with sarcomatous transformation, in contrast to their relative rarity in the West. While most patients had initial good responses to imatinib, second-line therapies were not as effective.

A Multicenter Phase II Study of Pazopanib in Patients with Unresectable Dermatofibrosarcoma Protuberans

Dermatofibrosarcoma protuberans (DFSP) is a soft-tissue sarcoma characterized by a high risk of local infiltration. The identification of the COL1A1-PDGFB t(17;22) translocation activating the PDGF pathway led to the use of imatinib in unresectable DFSP, with a response rate of 36-80%. Pazopanib is a multitarget tyrosine kinase inhibitor approved for soft-tissue sarcomas. We conducted a phase II study of patients with unresectable DFSP to evaluate the efficacy and safety of pazopanib. Patients received 800 mg of pazopanib daily. The primary endpoint was the objective response rate defined as the reduction of the largest diameter of the tumor by ≥30% at 6 months or at surgery. A total of 23 patients, including one pretreated with imatinib, were enrolled. With a median follow-up of 6.2 months (interquartile range= 5.6-7.8 months), five patients (22%, 95% confidence interval= 7-22%) had a partial response to pazopanib. The best objective response rate was 30% (95% confidence interval= 13-53%) using Response Evaluation Criteria in Solid Tumors. One patient with metastatic DFSP previously treated with imatinib died after 2.4 months. Nine patients (39%) discontinued the treatment owing to adverse events. Pharmacodynamics analyses of tumor samples were conducted: the enrichment of EGF and the EGFR-associated gene panel was associated with resistance, suggesting that EGFR-targeted therapies could be a therapeutic option to explore in DFSP. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01059656.

S1 guidelines for dermatofibrosarcoma protuberans (DFSP) - update 2018.

While dermatofibrosarcoma protuberans (DFSP) is a rare cancer entity overall, it is nevertheless the most common type of cutaneous sarcoma. The tumor is of fibroblastic origin and characterized by slow, undermining and locally destructive growth. Metastatic spread is very rare. Given its nonspecific clinical appearance, diagnosis is frequently delayed. Biopsy and subsequent histopathology are key diagnostic tools. Standard treatment for primary tumors consists of complete excision with surgical margins of 1 to 2cm. Smaller margins are associated with high local recurrence rates. Inoperable and metastatic DFSP may be treated with radiation therapy. Approximately 80-90% of DFSP lesions harbor a fusion gene that results in continuous activation of the PDGF-β signaling pathway. Consequently, molecular targeted therapy inhibiting PDGF-β is an effective option for advanced (inoperable) and metastatic DFSP. The first agent to be approved for systemic treatment of DFSP is the multikinase inhibitor imatinib, showing objective response rates of about 50% in clinical trials.

Current Update on the Molecular Biology of Cutaneous Sarcoma: Dermatofibrosarcoma Protuberans

Cutaneous sarcoma is a group of malignant mesenchymal tumors primarily involving the dermis, and it is characterized by extreme clinicopathological heterogeneity. Although its occurrence rate is rare, dermatofibrosarcoma protuberans (DFSP) is one of the most common types of dermal sarcoma. DFSP grows slowly and tends to relapse locally after inadequate resection. There are various histological variants of DFSP tumors and it often mimics benign lesions such as dermatofibroma and scar, which make accurate diagnosis difficult and delayed, and some cases progress to the stage where the tumor is unresectable. Recent advancements in cancer genetics and molecular biology methods have elucidated the COL1A1-PDGFB fusion gene, some novel fusion gene variants and pathways related to DFSP pathogenesis that have resulted in the evolution of cutaneous sarcoma diagnosis and treatment. For example, some clinical studies have confirmed the efficacy of imatinib methylate, an αPDGFR-targeted therapy for unresectable or metastatic DFSP. The present review summarizes recent updates in DFSP research, diagnostics, and treatment.

Sarcomas cutáneos: directrices para el diagnóstico y tratamiento. Dermatofibrosarcoma protuberans

Sarcomas comprise a broad group of tumors, many of whose biological behavior and aggressiveness differ from one type to another. The therapeutic approach is generally multidisciplinary and often complex. Developments in surgical and oncological dermatology during the last few decades have positioned dermatologists as specialists in the diagnosis and treatment of skin cancer. The aim of this article is to review the main soft tissue sarcomas that typically affect the skin. Dermatofibrosarcoma protuberans is a low-grade malignant sarcoma. It exhibits slow-growth, is locally invasive, and has low metastatic potential (<3%). Mohs micrographic surgery is the treatment of choice. The COL1A1-PDGFB translocation should be analyzed in cases of unclear diagnosis and when it is necessary to identify candidates for tyrosine kinase inhibitors. Imatinib is indicated for the treatment of locally advanced and metastatic dermatofibrosarcoma protuberans.

Dermatofibrosarcoma protuberans: A retrospective study of clinicopathologic features and related Akt/mTOR, STAT3, ERK, cyclin D1, and PD-L1 expression

Little is known regarding oncoproteins other than platelet-derived growth factor subunit B in dermatofibrosarcoma protuberans (DFSP). Moreover, the risk factors for worse prognosis are controversial. We sought to determine the clinicopathologic features and key factors for adverse outcome in DFSP, including the implication of expression of protein kinase B (Akt)/mammalian target of rapamycin (mTOR), signal transducer and activator of transcription 3 (STAT3), extracellular signal regulated kinase (ERK), cyclin D1, and programmed death ligand 1 (PD-L1). Clinicopathologic and immunohistochemical analyses were performed for 44 DFSPs having wide local excision and 92 dermatofibromas as controls. Compared with the 35 nonrecurrent DFSPs, the 9 recurrent DFSPs exhibited larger tumor size, deeper invasion beyond the subcutis, and more diverse histologic subtype. The fibrosarcomatous subtype revealed frequent mitotic figures and a high cyclin D1-positive index. The 2 metastatic DFSPs (1 each of the fibrosarcomatous and myxoid subtypes) demonstrated 4 and 11 instances of local recurrence, respectively, as well as larger tumor size, deeper invasion beyond the subcutis, and high expression of cyclin D1. Expression of Akt/mTOR, STAT3, ERK, and PD-L1 ranged from none or low in the primary skin lesions to high in the corresponding metastatic sites. Akt/mTOR and ERK were expressed more frequently in DFSP than in dermatofibroma. Lack of information on patients before hospital evaluation. Complex factors beyond fibrosarcomatous subtype may portend local recurrence or metastasis. Akt/mTOR, STAT3, ERK, and PD-L1 may be associated with development and/or progression of DFSP.

Long-term results of treatment of advanced dermatofibrosarcoma protuberans (DFSP) with imatinib mesylate – The impact of fibrosarcomatous transformation

BackgroundDermatofibrosarcoma protuberans (DFSP) is rare, infiltrating dermal neoplasm, characterized by indolent growth and low probability of metastases. The first effective systemic therapy in DFSP introduced into clinical practice was imatinib, demonstrating high activity in advanced cases. The aim of the study was to perform an analysis of patients with advanced DFSP treated with imatinib, with or without surgery, in routine clinical practice with long-term follow-up. Patients and methodsWe analyzed the data of 31 Caucasian patients (14 male, 17 female; median age 56 years) with locally advanced/initially inoperable and/or metastatic DFSP who started therapy with imatinib at initial dose 800 mg daily between 12/2004 and 07/2014. All diagnoses were confirmed cytogenetically for the presence of specific COL1A1-PDGFB fusion. Median follow-up time was 5.3 years. ResultsMetastases were present in 15 cases (8 – lungs, 5 – soft tissue, 2 – lymph nodes). Fibrosarcomatous transformation (FS-DFSP) was confirmed in 16 patients (52%). 5-year progression-free survival (PFS) rate was 58% (median 6.8 years), 5-year overall survival (OS) rate was 64% (median time for OS was not reached). The shorter PFS and OS correlated with FS-DFSP and presence of metastatic disease. 5-year PFS rate was 93% for classic DFSP and 33% for FS-DFSP. The best overall responses were: 21 partial responses (68%, including 8 FS-DFSP, but the responses were shorter than for classic DFSP), 6 stable disease (19%) and 4 progressive diseases (13%). Thirteen patients (47%) underwent resection of residual disease and nine of them remained free of disease, although imatinib was discontinued. Median survival after progression on imatinib was 19 months, and longer survival were observed only in cases were rescue surgery/radiotherapy was possible. ConclusionsOur results indicate the long-term activity of imatinib in therapy of inoperable and/or metastatic cases of DFSP, including FS-DFSP. Some DFSP patients initially evaluated as unresectable/metastatic or necessitating mutilating surgery turned resectable after imatinib therapy and this rational approach leading to complete remission maybe potentially curative.

Usefulness of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in dermatofibrosarcoma protuberans on treatment with imatinib

Dermatofibrosarcoma protuberans (DFSP) is a rare locally aggressive tumor with distant metastases being unusual. We present a case of metastatic DFSP treated with imatinib showing complete metabolic response to treatment.

Treatment of dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is a rare borderline malignant or potentially low-grade malignant neoplasm with a high local recurrence rate and a low risk of metastasis. DFSP usually occurs on the trunk in people aged 20-50 years, and is characterized by multiple indurated nodules varying in size and arising on atrophic plaques. Histologically, the tumor consists of uniform spindle cells which grow infiltratively and are arranged in a storiform or cartwheel pattern. The standard therapy of DFSP is wide local excision with a margin of 2-3 cm. Mohs' surgery and modified Mohs' surgery have shown a good prospect in the treatment of DFSP. Radiation therapy can serve as an adjuvant treatment after surgery. In recent years, the pathogenesis of DFSP has been further clarified and studies have shown that chromosomes 17 and 22 are rearranged in 90% of patients with DFSP. As a targeted drug, imatinib has been approved for the treatment of DFSP in patients with unresectable, metastatic and/or recurrent DFSP. Key words: Dermatofibrosarcoma; Surgical procedures, operative; Mohs surgery; Radiotherapy dosage; Molecular targeted therapy

Dermatofibrosarcoma Protuberans: an Update and Review

Dermatofibrosarcoma protuberans (DFSP) is a rare, infiltrative, spindle cell tumor with a propensity for deep invasion. Definitive treatment is with surgical excision, either Mohs micrographic surgery (MMS) or wide local excision (WLE). Metastasis is rare, but local recurrence is common. Imatinib mesylate is approved for the treatment of unresectable DFSP, recurrent DFSP that cannot be re-resected, and metastatic DFSP. Radiation therapy is sometimes used to treat unresectable DFSP or as an adjuvant treatment modality after surgical excision. MRI is not routinely used but is a useful imaging tool in atypical, recurrent, or difficult cases to better delineate tumor depth or involvement of critical structures. Close clinical follow-up is recommended every 6 to 12 months after treatment given the high rates of local recurrence.

Efficacy and Biological Activity of Imatinib in Metastatic Dermatofibrosarcoma Protuberans (DFSP).

To report on imatinib mesylate (IM) in patients with metastatic dermatofibrosarcoma protuberans (DFSP)/fibrosarcomatous (FS)-DFSP and on the impact of the treatment on tumor biology. Ten consecutive patients treated with IM from 2007 to 2015 for a metastatic relapse from DFSP/FS-DFSP were identified. FISH analysis for COL1A1-PDGFB was performed. Two IM-treated and 4 naïve FS-DFSP were transcriptionally profiled by RNAseq on HiScanSQ platform. Differential gene expression was analyzed with edgeR (Bioconductor), followed by hierarchical clustering and Principal Component Analysis. All cases featured fibrosarcomatous in the metastasis and retained the COL1A1-PDGFB. Best RECIST response was: 8 partial response, 1 stable disease, and 1 progressive disease. Median progression-free survival was 11 months. Five patients received surgery after IM and all relapsed. IM was restored in 4 patients with a new response. After IM, the most upregulated genes included those encoding for immunoglobulins and those affecting functions and differentiation of endothelial cells. Pathway enrichment analysis revealed upregulation in genes involved in antigen processing and presentation, natural killer-mediated cytotoxicity, and drug and xenobiotics metabolism. Conversely, a significant down-regulation of kinase signaling pathways was detected. All metastatic cases were fibrosarcomatous. Most patients responded to IM, but PFS was shorter than reported in published series which included both DFSP and FS-DFSP. All patients operated after IM had a relapse, suggesting that IM cannot eradicate metastatic cases and that the role of surgery is limited. Transcriptional profile of naïve and posttreatment samples pointed the contribution of immune infiltrates in sustaining the response to IM.

Diagnosis and treatment of dermatofibrosarcoma protuberans. European consensus-based interdisciplinary guideline

Dermatofibrosarcoma protuberans (DFSP) is a skin fibroblastic tumour that is locally aggressive, with a tendency for local recurrence, but rarely metastasizes. A unique collaboration of multi-disciplinary experts from the European Dermatology Forum (EDF), the European Association of Dermato-Oncology (EADO) and the European Organization of Research and Treatment of Cancer (EORTC) was formed to make recommendations on DFSP diagnosis and treatment, based on systematic literature reviews and the experts’ experience. Diagnosis is suspected clinically and confirmed by pathology. Analysis by fluorescence in situ hybridisation (FISH) or multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) to detect specific chromosomal translocations and fusion gene transcripts is useful to confirm a difficult DFSP diagnosis. Treatment is mainly surgical, with the aim to achieve complete resection of the tumour. In order to reduce the recurrence rate, the treatment of choice of DFSP seems to be Mohs’ micrographic surgery (MMS) and related variants. In hospitals where only standard histopathological procedures are available, standard excision with lateral safety margin of 3cm is advisable. Imatinib (Glivec®) is approved in Europe for the treatment of inoperable primary tumours, locally inoperable recurrent disease, and metastatic DFSP. Imatinib has also been given to patients with extensive, difficult-to-operate tumours for preoperative reduction of tumour size, but the usefulness of this attitude should be confirmed by clinical trials. Therapeutic decisions for patients with fibrosarcomatous DFSP should be primarily made by an interdisciplinary oncology team (‘tumour board’).

Target therapy of unresectable or metastatic dermatofibrosarcoma protuberans with imatinib mesylate: an analysis on 22 Chinese patients.

Dermatofibrosarcoma protuberans (DFSP) is a rare, plaque-like tumor of the cutaneous tissue occurring more on the trunk than the extremities and neck. More than 95% of DFSP present anomalies on the 17q22 and 22q13 chromosomal regions leading to the fusion of COL1A1 and PDGFB genes. Surgery is the optimal treatment for DFSP, but less effective in locally advanced or metastatic patients, as is the case with chemotherapy and radiotherapy. The aim of this study was to assess retrospectively the therapeutic activity and safety of imatinib on 22 Chinese patients with locally inoperative or metastatic DFSP at a single institution.In the collected data of 367 Chinese patients with DFSP, we analyzed retrospectively 22 patients with locally advanced or metastatic DFSP, all of whom received imatinib therapy at 1 center from January 2009 to October 2014. Patients were administered with imatinib at an initial dose of 400 mg and escalated to 800 mg daily after they developed imatinib resistance. The median follow-up time was 36 months, and the median treatment time was 15 months.The results showed that 10 locally advanced DFSP patients and 12 metastatic DFSP patients received imatinib therapy. Apart from 1 patient who developed primary imatinib resistance, 15 patients achieved partial remission (PR), and 6 patients achieved stable disease (SD). Both fibrosarcomatous DFSP and classic DFSP patients demonstrated similar response to imatinib. Median PFS was estimated to be 19 months. Median overall survival (OS) has not been reached, and estimated 1- and 3-year OS rates were 95.5% (21/22) and 77.3% (17/22), respectively. Four out of 10 patients with primarily unresectable DFSP received complete surgical resection after neoadjuvant treatment of imatinib.Imatinib therapy is well tolerated with a safety profile and is the therapy of choice in locally inoperative or metastatic DFSP. Neoadjuvant treatment of locally advanced or metastatic DFSP with imatinib improves surgical outcomes and may facilitate resection of difficult tumors.