Evolution of Dermatofibrosarcoma Protuberans to DFSP-Derived Fibrosarcoma: An Event Marked by Epithelial-Mesenchymal Transition-like Process and 22q Loss

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 10 µM at 72 h. No significant activity was observed with imatinib, palbociclib, everolimus, olaparib, gefitinib and erlotinib (IC50 all > 10 µM). In conclusion, we established MDFSP-S1, a new PDX and cell line model of imatinib-resistant DFSP with fibro-sarcomatous transformation.

Extensive analysis of 59 sarcoma-related fusion genes identified pazopanib as a potential inhibitor to COL1A1-PDGFB fusion gene

Sarcomas are malignant mesenchymal tumors that are extremely rare and divergent. Fusion genes are involved in approximately 30% of sarcomas as driver oncogenes; however, their detailed functions are not fully understood. In this study, we determined the functional significance of 59 sarcoma-related fusion genes. The transforming potential and drug sensitivities of these fusion genes were evaluated using a focus formation assay (FFA) and the mixed-all-nominated-in-one (MANO) method, respectively. The transcriptome was also examined using RNA sequencing of 3T3 cells transduced with each fusion gene. Approximately half (28/59, 47%) of the fusion genes exhibited transformation in the FFA assay, which was classified into five types based on the resulting phenotype. The sensitivity to 12 drugs including multityrosine kinase inhibitors was assessed using the MANO method and pazopanib was found to be more effective against cells expressing the COL1A1-PDGFB fusion gene compared with the others. The downstream MAPK/AKT pathway was suppressed at the protein level following pazopanib treatment. The fusion genes were classified into four subgroups by cluster analysis of the gene expression data and gene set enrichment analysis. In summary, the oncogenicity and drug sensitivity of 59 fusion genes were simultaneously evaluated using a high-throughput strategy. Pazopanib was selected as a candidate drug for sarcomas harboring the COL1A1-PDGFB fusion gene. This assessment could be useful as a screening platform and provides a database to evaluate customized therapy for fusion gene-associated sarcomas.

Genetic and environmental reprogramming of the sarcoma epigenome

Sarcomas are rare and heterogenous mesenchymal tumors occurring in soft tissue and bone. The World Health Organization Classification of sarcomas comprises more than hundred different entities which are very diverse in their molecular, genetic and epigenetic signatures as they are in their clinical presentations and behaviors. While sarcomas can be associated with an underlying hereditary cancer predisposition, most sarcomas developed sporadically without identifiable cause. Sarcoma oncogenesis involves complex interactions between genetic, epigenetic and environmental factors which are intimately related and intensively studied. Several molecular discoveries have been made over the last decades leading to the development of new therapeutic avenues. Sarcoma research continues its effort toward a more specific and personalized approach to all sarcoma sub-types to improve patient outcomes and this through world-wide collaboration. This chapter on "Genetic and Environmental Reprogramming of the Sarcoma Epigenome" provides a comprehensive review of general concepts and epidemiology of sarcoma as well as a detailed description of the genetic, molecular and epigenetic alterations seen in sarcomas, their therapeutic implications and ongoing research. This review also presents evidenced-based data on the environmental and occupational factors possibly involved in the etiology of sarcomas and a brief discussion on the role of the microbiome in sarcoma.

Coamplification of 12q15 and 12p13 and homozygous CDKN2A/2B deletion: synergistic role of fibrosarcomatous transformation in dermatofibrosarcoma protuberans with a cryptic COL1A1-PDGFB fusion

Dermatofibrosarcoma protuberans (DFSP) is characterized by collagen type I alpha 1 chain-platelet-derived growth factor B chain (COL1A1-PDGFB) fusion. We present a case of fibrosarcomatous DFSP with lung metastasis in a 53-year-old man. Histologically, the primary and metastatic tumors were composed of high-grade fibrosarcomatous component with varying myxoid changes, while only a small focus of the classic DFSP element was identified in the primary lesion. No evidence of COL1A1-PDGFB fusion was identified by routine fluorescence in situ hybridization (FISH). Subsequent next-generation sequencing and COL1A1 break-apart FISH identified the fusion. In addition, coamplification of 12q15 and 12p13, along with CDKN2A/2B deletion, was confirmed to be limited to the fibrosarcomatous component. The current case is a novel FS-DFSP with cryptic COL1A1-PDGFB fusion. This is the first published example of DFSP harboring coamplification of 12q and 12p sequences. More importantly, the genetic aberrations restricted to the fibrosarcomatous component indicated a synergistic role of higher-grade progression.

Epigenetics of Cutaneous Sarcoma

Epigenetic changes influence various physiological and pathological conditions in the human body. Recent advances in epigenetic studies of the skin have led to an appreciation of the importance of epigenetic modifications in skin diseases. Cutaneous sarcomas are intractable skin cancers, and there are no curative therapeutic options for the advanced forms of cutaneous sarcomas. In this review, we discuss the detailed molecular effects of epigenetic modifications on skin sarcomas, such as dermatofibrosarcoma protuberans, angiosarcoma, Kaposi's sarcoma, leiomyosarcoma, and liposarcoma. We also discuss the application of epigenetic-targeted therapy for skin sarcomas.

Clinicopathological features of fibrosarcomatous dermatofibrosarcoma protuberans and the construction of a back-propagation neural network recognition model

BACKGROUND

Fibrosarcomatous dermatofibrosarcoma protuberans (FS-DFSP) is a form of tumor progression of dermatofibrosarcoma protuberans (DFSP) with an increased risk of metastasis and recurrence. Few studies have compared the clinicopathological features of FS-DFSP and conventional DFSP (C-DFSP).

OBJECTIVES

To better understand the epidemiological and clinicopathological characteristics of FS-DFSP.

METHODS

We conducted a cohort study of 221 patients diagnosed with DFSP and built a recognition model with a back-propagation (BP) neural network for FS-DFSP.

RESULTS

Twenty-six patients with FS-DFSP and 195 patients with C-DFSP were included. There were no differences between FS-DFSP and C-DFSP regarding age at presentation, age at diagnosis, sex, size at diagnosis, size at presentation, and tumor growth. The negative ratio of CD34 in FS-DFSP (11.5%) was significantly lower than that in C-DFSP (5.1%) (P = 0.005). The average Ki-67 index of FS-DFSP (18.1%) cases was significantly higher than that of C-DFSP (8.1%) cases (P < 0.001). The classification accuracy of the BP neural network model training samples was 100%. The correct rates of classification and misdiagnosis were 84.1% and 15.9%.

CONCLUSIONS

The clinical manifestations of FS-DFSP and C-DFSP are similar but have large differences in immunohistochemistry. The classification accuracy and feasibility of the BP neural network model are high in FS-DFSP.

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.

Dermatofibrosarcoma protuberance in a black African cohort-a clinicopathologic study

Background

Dermatofibrosarcoma protuberance (DFSP) is the commonest, yet rare, dermal sarcoma globally. There are few reports in the literature of this neoplasm in Nigerians and indeed in sub-Saharan Africa. This study documents our institutional practice observation and compares it with those from other regions of the world.

Methods and materials

This study was a retrospective review of all cases of histologically diagnosed DFSP at the University College Hospital, Ibadan, Nigeria, spanning a period of 27 years (January 1989–December 2016). Data on patient age, gender, tumour location, size, tumour recurrence and metastasis status were obtained from clinical and surgical pathology archival files and records.

Results

Sixty-nine cases of DFSP were recorded over the period reviewed with a male–female ratio of 1.6:1. The mean age of the study population was 39.6 years. The youngest patient was 5-year old, while the oldest was 86 years and the modal age group was the 4th decade. The trunk was the commonest anatomic tumour location. Recurrences were seen in seven cases with recurrence interval ranging from 6 to 240 months. The correlation between tumour size and age was non-significant (r = −0.183; p = 0.182). There was fibrosarcoma-like transformation in three cases (4.3%) studied.

Conclusion

Dermatofibrosarcoma protuberance is rare in our population and occurs more commonly in males and on the trunk. Recurrence can occur beyond the recommended follow-up period of 10 years.

Atypical fibroxanthoma and pleomorphic dermal sarcoma: A reappraisal

BACKGROUND

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) share clinical, pathological, immunohistochemical and molecular features, though PDS is associated with a more aggressive behavior.

METHODS

We reviewed 71 tumors fulfilling criteria for AFX and PDS to further stratify their biological potential.

RESULTS

Lesions were mainly located on the scalps of elderly men, and were often ulcerated. One case was necrotic, one showed vascular invasion, and one showed perineural invasion. Fifty-one tumors were limited to reticular dermis (71.8%), 20 invaded subcutaneous tissue, focally in 13 cases (18.3%), and diffusely in seven (9.9%). Subcutaneous invasion was present significantly more often in tumors showing predominantly spindle compared to pleomorphic/mixed cell morphology (P = 0.02). At a follow-up of 17-125 months, 4 cases recurred locally, 4, 6, 10 and 13 months after surgery; no metastases were observed. Three tumors were composed of spindle cells, and one of clear cells. Three cases had margins focally involved, while the fourth case had clear margins.

CONCLUSION

Depth of invasion and state of margins are criteria predicting prognosis in AFX/PDS; in addition, spindle cell morphology seems to be related to a more infiltrative pattern of growth and to aggressiveness. Grouping these tumors on a morphologic base could help to clarify their different biological behavior.

Dermatofibrosarcoma protuberans with fibrosarcomatous transformation arising at the site of breast implant

Fibrosarcomatous transformation of dermatofibrosarcoma protuberans (DFSP) is a rare variant with higher risk of recurrence and metastasis, and no known associations with breast implants. We report a rare case of fibrosarcomatous dermatofibrosarcoma protuberans arising at the site of breast implant in a 33-year-old patient followed by brief discussion on fibrosarcomatous DFSP.

Genomic and transcriptomic features of dermatofibrosarcoma protuberans: Unusual chromosomal origin of the COL1A1-PDGFB fusion gene and synergistic effects of amplified regions in tumor development

The dermatofibrosarcoma protuberans family of tumors (DPFT) comprises cutaneous soft tissue neoplasms associated with aberrant PDGFBR signaling, typically through a COL1A1-PDGFB fusion. The aim of the present study was to obtain a better understanding of the chromosomal origin of this fusion and to assess the spectrum of secondary mutations at the chromosome and nucleotide levels. We thus investigated 42 tumor samples from 35 patients using chromosome banding, fluorescence in situ hybridization, single nucleotide polymorphism arrays, and/or massively parallel sequencing (gene panel, whole exome and transcriptome sequencing) methods. We confirmed the age-associated differences in the origin of the COL1A1-PDGFB fusion and could show that it in most cases must arise after DNA synthesis, i.e., in the S or G2 phase of the cell cycle. Whereas there was a non-random pattern of secondary chromosomal rearrangements, single nucleotide variants seem to have little impact on tumor progression. No clear genomic differences between low-grade and high-grade DPFT were found, but the number of chromosomes and chromosomal imbalances as well as the frequency of 9p deletions all tended to be greater among the latter. Gene expression profiling of tumors with COL1A1-PDGFB fusions associated with unbalanced translocations or ring chromosomes identified several transcriptionally up-regulated genes in the amplified regions of chromosomes 17 and 22, including TBX2, PRKCA, MSI2, SOX9, SOX10, and PRAME.

The efficacy of Mohs micrographic surgery over the traditional wide local excision surgery in the cure of dermatofibrosarcoma protuberans

Usually most patients with dermatofibrosarcoma protuberans (DFSP) may present rather late when the tumor is in protuberant phase due to its rarity and indolent onset. It has a high propensity for local recurrence and destructive nature. Management of DFSP requires a biopsychosocial and Multidisplinary approach regardless of the clinical or immunohistochemical variant. Surgery is the Gold standard management of localized disease. DFSP rarely exhibits any lymphatic or hematogenous dissemination. It is because of its high recurrence rate associated with Wide Local Excision (WLE), the introduction of Mohs micrographic surgery (MMS) has really helped in reducing the rates of recurrence of DFSP. Thus, the aim of this meta-analysis and systemic review is to advocate for MMS over WLE for DFSP and other cutaneous malignancies using DFSP as a prototype. The objective of this study were to conduct a meta-analysis on comparative surgical methods used in the cure of DFSP with regards to WLE verses MMS, to evaluate the cure rates with relation to recurrence rates, offer a recommendation on the various treatment modalities based on the location of lesion, and use of adjuvant therapy in different clinical-medical setups. A comprehensive retrospective analysis search in EMBASE, Google Scholar and Medline (PubMed) for studies published from 2008 to 2018 containing the surgical management of DFSP with WLE verses MMS were reviewed. Five studies of moderate-quality evidence (level B) with a pooled patient load of 684 was analyzed and found for recurrence of DFSP after WLE and MMS to be 9.10% and 2.72% respectively after an average follow-up time for both groups of 5.32 years with a female predominance of 1.58. The trunk is the commonest site for the DFSP lesion which was at 52.80% then the upper and lower extremities zones and the head and neck zones at 31.75% and 15.45% respectively. The pooled adjusted odds ratio (OR) analysis indicated that there was a direct relationship with regards the reduced recurrence rate of DFSP in the MMS group compared to the WLE group (OR:0.31;95%; CI :0.17-0.56). Furthermore, there was significant association between the reduced recurrence rate with the MMS in DFSP patients with a statistical P-value of 0.0001 at 95% CI. The expected increased recurrence rate by zones was in WLE head and neck zone at 38.19% then trunk and extremities zone at 13.34%. In the MMS group it was at of 23.4% as compared to 16.0% in the head and neck zone. Mohs Micrographic Surgery (MMS) is more efficacious in the cure rate and recurrence reduction of DFSP and should be advocated for as first line therapy especially in high recurrence prone zones.

A novel MAP3K7CL-ERG fusion in a molecularly confirmed case of dermatofibrosarcoma protuberans with fibrosarcomatous transformation

Dermatofibrosarcoma protuberans (DFSP) is a translocation-associated, low-grade sarcoma with fibroblastic differentiation. It is the most common superficial sarcoma, almost exclusively arising within the dermis. In a minority of cases, there is a transition from the conventional morphology to a fibrosarcomatous pattern, known as a fibrosarcomatous DFSP (FS-DFSP). Although a number of different molecular alterations have been described to account for this transformation, it remains poorly understood. Herein we report the first case of a FS-DFSP with a fusion between ERG, an ETS family transcription factor, and MAP3K7CL, a kinase gene rarely observed in fusion gene events.

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

OPINION STATEMENT

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.

Kutane Sarkome

Cutaneous sarcomas comprise a heterogeneous group of mesenchymal spindle cell tumors of the dermis and subcutis, one of the best-known entities being dermatofibrosarcoma protuberans. Other sarcomas addressed in this review include a typical fibroxanthoma, cutaneous undifferentiated pleomorphic sarcoma, leiomyosarcoma, liposarcoma, and angiosarcoma. With the exception of dermatofibrosarcoma protuberans, which has its peak incidence in middle-aged adults, cutaneous sarcomas usually occur in elderly individuals starting in the sixth or seventh decade of life. The pathogenesis of the various disease entities is not uniform and has not been definitively ascertained. Histology is the key to arriving at a correct diagnosis, and should always include ruling out other dermal neoplasms such as melanoma. In recent years, molecular genetic methods have provided greater insight into the pathogenesis, thus paving the way for new targeted therapies. Treatment of choice for cutaneous sarcomas is excision with sufficient surgical margins. Adjuvant and neoadjuvant therapeutic concepts include radiation therapy and the use of targeted therapies or chemotherapies. Local recurrences have frequently been reported in cutaneous sarcomas. Unlike soft tissue sarcomas, the prognosis in terms of survival - with the exception of angiosarcoma - is very good if treated adequately, a fact that should be emphasized to patients.

EGFR is involved in dermatofibrosarcoma protuberans progression to high grade sarcoma

Dermatofibrosarcoma protuberans (DFSP), amounting to 6% of all soft tissue sarcomas, has a slow growth rate, contrasting with a likelihood for local recurrence and a 10-20% evolution to higher-grade sarcoma, or "transformed DFSP" (DFSP-T). At molecular level, the characteristic COL1A1-PDGFB rearrangement, leading to sustained PDGFR signaling, is not linked to the evolutive potential. Here, we studied EGFR, another tyrosine kinase receptor, using laser-microdissection to select the different histologic components of DFSP (DFSP center, DFSP infiltrative periphery, DFSP-T higher-grade sarcoma), in 22 patients followed over 3 to 156 months. EGFR protein and mRNA were expressed in 13/22 patients with DFSP or DFSP-T, and increased with tumor progression, both in microdissected areas of higher-grade sarcomas and in microdissected areas of local extension. No cancer-associated EGFR gene mutation or copy-number variation, nor any KRAS, BRAF, NRAS hotspot mutations were found in any microdissected area. Among epithelial-mesenchymal transition factors tested, SNAIL 1/2 had the same expression pattern as EGFR while ZEB1/2 or TWIST1/2 did not. Using a proteome profiler phospho-kinase array on 3 DFSP and 3 DFSP-T cryopreserved tissue samples, EGFR phosphorylation was detected in each case. Among EGFR downstream pathways, we found positive correlations between phosphorylation levels of EGFR and STAT5a/b (r = 0.87, p < 0.05) and TOR (r = 0.95, p < 0.01), but not ERK in the MAPK pathway (r = -0.18, p > 0.70). We thus demonstrated that in DFSP evolution to high grade sarcoma, EGFR and SNAIL were involved, with EGFR activation and signaling through TOR and STAT5a/b downstream effectors, which could lead on to new therapies for advanced DFSP.

Unforeseen clonal evolution of tumor cell population in recurrent and metastatic dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is a very rare soft tissue sarcoma, generally of low-grade malignancy. DFSP is locally aggressive with a high recurrence rate, but metastasis occurs rarely. To investigate the mechanism of metastasis in DFSP, we analyzed the whole exome sequencing data of serial tumor samples obtained from a patient who had a 10-year history of recurrent and metastatic DFSP. Tracking various genomic alterations, namely somatic mutations, copy number variations, and chromosomal rearrangements, we observed a dramatic change in tumor cell population during the occurrence of metastasis in this DFSP case. The new subclone that emerged in metastatic DFSP harbored a completely different set of somatic mutations and new focal amplifications, which had not been observed in the primary clone before metastasis. The COL1A1-PDGFB fusion, characteristic of DFSP, was found in all of the serial samples. Moreover, the break position on the fusion gene was identical in all samples. Based on these observations, we suggest a clonal evolution model to explain the mechanism underlying metastasis in DFSP and identified several candidate target genes responsible for metastatic DFSP by utilizing The Cancer Genome Atlas database. This is the first study to observe clonal evolution in metastatic DFSP and provide insight for a possible therapeutic strategy for imatinib-resistant or metastatic DFSP.

Clinical Features, Pathological Findings and Treatment of Recurrent Dermatofibrosarcoma Protuberans

Dermatofibrosarcoma protuberans (DESP) is a relatively rare and low-grade tumor of the skin and soft tissue. We review the clinical features, pathological findings and management of recurrent DESP with the aim to improve our understanding of this rare tumor. Fifty-seven patients were diagnosed with recurrent DFSP. The mean age at the presentation of DFSP was 30.9 years. The mean age at diagnosis of DFSP was 40.2 years. Chest wall was the dominant location. The histopathological diagnosis was ordinary DFSP (O-DFSP) in 46 cases and fibrosarcomatous DFSP (FS-DFSP) in 11 cases. No differences were noted between FS-DFSP and conventional DFSP in age at presentation and diagnosis, tumor size, as well as CD34 and SMA expression (P > 0.05). However, the time course to recurrence in FS-DFSP group was less than that in O-DFSP group (P = 0.038). All of the patients were treated with Mohs micrographic surgery (MMS). On follow-up, none of the patients had tumor recurrence. Our data demonstrated that the clinical features of recurrent DFSP are non-specific and variable. Our current practice suggests that MMS is very useful treatment choice for recurrent DFSP.

Programmed death-ligand 1 expression is associated with fibrosarcomatous transformation of dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is a locally invading tumor, characterized by the presence of the collagen type I α 1 (COL1A1)-platelet-derived growth factor (PDGF) β fusion gene. We herein report the case of a 31-year-old man with a history of resection of an abdominal wall DFSP. The patient presented with chest pain and a computed tomography scan revealed a large mass in the posterior mediastinum and another mass in the right lung. The mediastinal mass was a sarcomatous lesion expressing the COL1A1-PDGFβ fusion gene, suggesting that it represented a metastasis of the DFSP following fibrosarcomatous (FS) transformation. Following resection of the mediastinal metastasis and subsequent radiotherapy, the mass in the right lung was also resected. Due to the emergence of pleural and pancreatic tail metastases, the patient was treated with a combination therapy of adriamycin and ifosfamide. After five courses, the disease progressed and the patient was subsequently treated with pazopanib for ~2 months until further progression. Three years after the diagnosis of the mediastinal metastasis of DFSP, the patient was referred to another hospital for palliative care. The expression of programmed cell death 1 ligand (PD-L1) in the primary and metastatic tumors was investigated: PD-L1 expression was detected in the metastasis but not in the primary tumor. Given that the metastatic tumor exhibited FS transformation (DFSP-FS), PD-L1 expression may be induced by FS transformation, contributing to the metastasis through escape from immune surveillance. Further investigation of the PD-L1 pathway in DFSP and DFSP-FS in primary as well as metastatic sites is required to evaluate the clinical efficacy of therapies targeting the PD-L1 signaling cascade.