Dermatofibrosarcoma protuberans of the breast.

Dermatofibrosarcoma protuberans (DFSP) of the breast is an infrequent soft tissue sarcoma that usually affects young to middle-aged women. Our case report describes a unique occurrence of DFSP of the breast in an adolescent girl, which was initially being managed as a keloid for 2 years under dermatology despite being refractory to treatment. Once the diagnosis of DFSP was confirmed through punch biopsy, our patient underwent surgical excision of the lesion under general anaesthesia. Our patient was at an increased risk of damage to the ductal system due to proximity of the lesion to the nipple-areolar complex, warranting the need for early recognition and treatment. As demonstrated by our case, DFSP of the breast can be difficult to diagnose since it resembles a range of benign and malignant pathologies of the breast.

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.

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.

Disease-Specific Mortality of Dermatofibrosarcoma Protuberans After Mohs Surgery Versus Wide Local Excision: A Systematic Review and Meta-Analysis.

BACKGROUND: Although advances have been made in the understanding of recurrence patterns in dermatofibrosarcoma protuberans, the current understanding of disease-specific mortality after surgical management is limited. OBJECTIVE: To understand disease-specific mortality rates associated with dermatofibrosarcoma protuberans treated with wide local excision (WLE) versus Mohs micrographic surgery (MMS). MATERIALS AND METHODS: A systematic literature search was conducted on March 6, 2023, to identify patients treated with MMS or WLE for dermatofibrosarcoma protuberans. RESULTS: A total of 136 studies met inclusion criteria. Overall, the disease-specific mortality rate was not significantly different after treatment with MMS (0.7%, confidence interval [CI] 0.1-1.2, p : 0.016) versus WLE (0.9%, CI 0.6-1.2, p < .001). For recurrent tumors, the MMS treatment group had a statistically significantly lower disease-specific mortality rate (1.0%, CI 0.0-2.0, p 0.046) compared with the WLE treatment group (3.5%, CI 2.0-5.1, p < .001). The mean follow-up for all studies was 57.6 months. CONCLUSION AND RELEVANCE: The authors' meta-analysis suggests there is no substantial difference in disease-specific mortality between MMS and WLE in patients with dermatofibrosarcoma protuberans, except in the case of recurrent tumors, where MMS seems to confer a survival advantage.

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.

[Fascio-cutaneous exeresis of a dermatofibrosarcoma of Darier-Ferrand of the right flank]. / Exérèse fascio-cutanée d'un dermatofibrosarcome de Darier-Ferrand du flanc droit.

INTRODUCTION: Darrier-Ferrand dermatofibrosarcoma (DFSC) is the most common cutaneous sarcoma. It generally affects subjects with an average age of 40 years, without gender or race predominance. It is a tumour characterised by a slow evolution and local aggressiveness. The reasons for consultation are pain, pruritus or rapidly progressive evolution. There are no specific imaging studies for this tumour. The diagnosis of certainty is based on immunohistochemistry with positive CD34 labelling. Treatment is surgical based on wide excision. MATERIAL AND METHODS: This is an observation of a patient operated in our department for the initial diagnosis of cutaneous leiomyosarcoma of the right flank that rapidly increased in volume to 10cm in six months. A large fasciocutaneous excision was performed. The postoperative course was simple. DISCUSSION: In our patient, this lesion occurred on an old burn scar. This notion of skin trauma preceding the appearance of DFSC is reported in 10 to 20% of cases. The rapid increase in volume was the reason for consultation. The diagnosis of DFSC could only be made on definitive analysis of the surgical specimen, which showed positive immunostaining for CD34. The occurrence of metastases, although rare, confers a survival of no more than two years. The prognostic factors depend on the quality of the surgical excision, the presence of metastases and certain locations (head, neck), which make the surgery particularly mutilating. Only long-term monitoring attests to definitive cure, given the frequency of recurrence. CONCLUSION: DFSC is a rare and slowly evolving tumour. Wide surgical excision should be attempted in most cases. In inoperable cases, the use of targeted therapies (IMATINIB) has led to complete cures in some cases.

Survival outcomes of rare cutaneous malignancies within an insured cohort of patients, 1988-2018.

BACKGROUND: There are limited survival data on cutaneous angiosarcoma (CAS), dermatofibrosarcoma protuberans (DFSP), Merkel cell carcinoma (MCC), and sebaceous carcinoma (SC). OBJECTIVE: To analyze survival trends in CAS, DFSP, MCC, and SC among a racially diverse, insured cohort of patients. METHODS: Using data from the Kaiser Permanente Southern California Cancer Registry, we identified adults diagnosed with CAS, DFSP, MCC, or SC between January 1, 1988 and December 31 2018, followed through December 31, 2021. RESULTS: Our cohort consisted of 83 diagnoses of CAS, 490 diagnoses of DFSP, 411 diagnoses of MCC, and 249 diagnoses of SC. Our analysis revealed no significant differences in overall or disease-specific 1000 person-years mortality rates among our populations of non-Hispanic Whites, Hispanics, African American/Blacks, and Asian American/Pacific Islanders diagnosed with CAS, DFSP, MCC, or SC. On multivariate analysis, controlling for patient and tumor characteristics, there was similarly no increased risk of overall mortality for minorities diagnosed with CAS, DFSP, MCC, or SC. LIMITATIONS: Retrospective nature of the analysis and small sample size. CONCLUSION: Contrary to existing literature, our results show a notable lack of racially driven survival disparities among insured individuals with CAS, DFSP, MCC, and SC, emphasizing the importance of health care coverage.

A study of collagen refractility in dermatofibroma and dermatofibrosarcoma protuberans using diffractive microscopy.

BACKGROUND: Diffractive microscopy creates contrast within samples that are otherwise uniform under bright light. This technique can highlight subtle differences in refractive indices within birefringent samples containing varying amounts of mature collagen. Dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP) possess differences in their mature collagen content and, therefore, may be distinguishable using diffractive microscopy. METHODS: Two hundred forty-two DF and 85 DFSP hematoxylin-eosin (H&E)-stained specimens were analyzed using diffractive microscopy. Data regarding the distribution pattern and strength of refractility was recorded. RESULTS: DFSP was more frequently found to be focally, weakly, or non-refractile (82.9%; n = 68) under diffractive microscopy, while DF more often showed diffusely bright refractility (52.9%; n = 128). DFSP samples with diffuse refractility in portions of the lesion (17.1%; n = 14) also exhibited a unique checkerboard pattern distinct from that which was seen in DF samples. CONCLUSIONS: The absence of diffuse refractility was more closely associated with DFSP, as was the presence of a unique checkerboard diffraction pattern. Despite high sensitivity (Sn = 82.9%), absent refractility was not a specific test (Sp = 52.9%), with 47.1% (n = 114) of DF samples sharing this feature. The distinction between DF and DFSP is often diagnosed using H&E alone. In difficult cases, examination of collagen under diffractive microscopy may be useful in distinguishing DFSP from DF and provide an alternative cost-effective tool to immunohistochemical staining.

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.

Connexin 43 in Dermatofibroma and Dermatofibrosarcoma Protuberans: Diagnostic, Pathogenic, and Therapeutic Implications.

ABSTRACT: Connexins play a crucial role in the formation of gap junctions that connect cells to each other, as well as cells to the surrounding environment. In recent years, connexin 43 has been extensively studied in various human tumors. In this study, we conducted an immunohistochemical analysis to evaluate the expression of connexin in 16 dermatofibromas (DFs) and 13 dermatofibrosarcoma protuberans (DFSP). Connexin was diffusely expressed in the cytoplasm of all DFs with moderate or strong intensity, whereas all DFSPs showed negative staining. In addition to its diagnostic implications, the loss of Cx43 may elucidate the invasive capacity of DFSP and offer a potential avenue for future therapeutic interventions.

Dermatofibrosarcoma protuberans: A rare presentation in the scalp. Case report.

BACKGROUND: Dermatofibrosarcoma protuberans of the scalp (DFSP) is a rare soft tissue neoplasm originating from the dermal layer of the skin, usually affecting the adults. CASE REPORT: The current case report presents a 48-year old male with a huge lump on the right side of parietal region. A wide local excision of the tumor was performed and the excised specimen was sent for histopathological examination. Histopathology and Immunohistochemistry was suggestive of DFSP. CONCLUSION: Dermatofibrosarcoma protuberans is a rare neoplasm affecting the head and neck region. This unusual entity is more likely to recur when a small margin of surgical excision is performed. Wide local excision is the gold standard treatment and radiotherapy is preferred in recurrent diseases.

Survival Outcomes and Prognostic Factors of Dermatofibrosarcoma Protuberans: A Population-Based Retrospective Cohort Analysis.

BACKGROUND: Limited information is available regarding survival outcomes and risk factors of dermatofibrosarcoma protuberans (DFSP). OBJECTIVE: To investigate the clinicopathologic characteristics and survival outcomes of DFSP. MATERIALS AND METHODS: The study cohort (7,567 patients) was selected from the Surveillance, Epidemiology, and End Results Program (2000-2018). Demographic and clinicopathologic variables, survival outcomes, and prognostic factors were analyzed. RESULTS: A total of 5,640 (74.53%) and 1,927 (25.47%) tumors were located in the skin and soft tissue, respectively. The median follow-up duration was 92 months. Median follow-up times were similar between patients with lymph node (107 months) and distant (102 months) metastases; the median survival time of the 89 patients (1.18%) who died of DFSP was significantly short (41 months, p < .001). Independent risk factors for cancer-specific mortality included age at diagnosis, histologic grade, and tumor size. Patients with tumors ≥10 cm in size or histologic grade III had significantly higher DFSP-specific mortality (7.07% and 10.08%, respectively, p < .001). Tumor locations and surgical procedures did not significantly influence survival. CONCLUSION: Dermatofibrosarcoma protuberans has a favorable survival prognosis, even in patients with node-positive or distant metastases. Dermatofibrosarcoma protuberans-specific mortality is significantly higher in patients with grade III or large (≥10 cm) tumors.

An update on selected cutaneous (myo) fibroblastic mesenchymal tumors.

Cutaneous (myo)fibroblastic tumors constitute a group of tumors with overlapping clinicopathological features and variable biologic behavior. In the present review we focus on the histomorphology, immunohistochemical profile and molecular background of the following entities: dermatofibrosarcoma protuberans (DFSP), CD34-positive fibroblastic tumor (SCD34FT), myxoinflammatory sarcoma (MIFS), low-grade myofibroblastic sarcoma, solitary fibrous tumor and nodular fasciitis. Although some of these entities typically arise in deep-seated locations, they may occasionally present as cutaneous/superficial tumors and might be challenging to recognize. This review covers in depth the latest advances in molecular diagnostics and immunohistochemical markers that have significantly facilitated the correct classification and diagnosis of these neoplasms.

Wide local excision, Mohs micrographic surgery, and reconstructive options for treatment of dermatofibrosarcoma protuberans of the breast: A retrospective case series from Mayo Clinic.

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) of the breast is a dermal fibroblastic neoplasm requiring wide excisional margins due to recurrence rates ranging from 26 to 60%. The current literature on reconstructive options and utility of Mohs micrographic surgery for DFSP of the breast is scarce. We describe surgical management of DFSP of the breast at our institution with the largest case series reported to date. METHODS: A retrospective review was performed of women who underwent surgery for DFSP of the breast at our institution between 1990 and 2019. Continuous data was summarized using mean, median, and range; categorical data was summarized with frequency count and percentage. Preoperative lesion size and postoperative defect size were evaluated using 2-sided Fisher exact test, and p-values < 0.05 were considered statistically significant. RESULTS: Nine patients underwent wide local excision (WLE) with reconstruction including pedicled latissimus dorsi flaps (n = 2), local flap advancement (n = 2), mastectomy with implant (n = 1), oncoplastic breast reduction (n = 1), and skin grafts (n = 3). Nine underwent Mohs micrographic surgery (MMS) with complex primary closure. Mean postoperative maximum wound defect size for WLE was 10.8 cm versus 7.0 cm for MMS with no statistical significance (p = 0.77). Mean preoperative maximum lesion size for WLE was 6.4 cm versus 3.3 cm for MMS with no statistical significance (p = 0.07). Complications with WLE included wound dehiscence in three patients and seroma in one patient. No complications were reported with MMS and primary closure. Recurrence was reported in one WLE patient, which was successfully detected despite flap coverage and resected without complications. Median follow-up for the patients without recurrence was 5.0 years, with two patients in MMS cohort lost to follow-up. Five-year overall survival was 100%. CONCLUSIONS: MMS and WLE are both viable surgical options for managing DFSP of the breast. MMS could potentially minimize reconstructive needs due to smaller average defect size and result in fewer complications but may also result in asymmetry. Immediate flap reconstruction, especially in larger defects, can achieve excellent aesthetic outcomes for patients with DFSP of the breast without compromising detection of disease recurrence.

[Micrographic controlled surgery in everyday dermatosurgery]. / Mikroskopisch kontrollierte Chirurgie im dermatochirurgischen Alltag.

Micrographic controlled surgery (MCS) has become established in dermatosurgery in recent years and includes various methods to enable the histologically proven complete resection of malignant cutaneous tumors, while at the same time sparing tumor-free tissue in the immediate vicinity as much as possible. MCS is of great importance in the surgical treatment of cutaneous malignancies in so-called problem locations and aggressive tumor subtypes. Indications for MCS include basal cell carcinoma, cutaneous squamous cell carcinoma, Bowen's disease and Bowen's carcinoma, melanoma in chronic light-damaged skin with acral lentiginous melanoma, dermatofibrosarcoma protuberans (DFSP), and Merkel cell carcinoma. However, other tumor entities are also treated using MCS, such as extramammary Paget's disease and various cutaneous sarcomas. All procedures subsumed under MCS have in common the marking of the surgical specimen for topographical orientation, which provides assignment of remaining tumor remnants. Various methods of MCS (3D histology, the horizontal method or Mohs surgery) are presented in this article. Furthermore, this article aims to raise awareness of the possibilities and limitations of micrographically controlled surgery.

Dermatofibrosarcoma protuberans of the scalp: Surgical management in a multicentric series of 11 cases and systematic review of the literature.

BACKGROUND: Dermatofibrosarcoma protuberans is a rare, slow-growing soft-tissue malignancy originating in the dermis that is characterized by an infiltrating growth pattern with a marked tendency of local recurrence. Complete surgical resection with pathological margin clearance must be achieved to reduce the risk of tumor recurrence. Resulting defects often require extensive reconstructive procedures. Dermatofibrosarcoma protuberans of the scalp poses particular challenges owing to the proximity to the face and brain. This study aims to evaluate treatment options and proposes an algorithm for management of scalp dermatofibrosarcoma protuberans based on a multicentric case series and systematic review of the literature. METHODS: A retrospective multicentric chart analysis of 11 patients with scalp dermatofibrosarcoma protuberans who presented within the last 20 years was performed regarding demographic data, pathological tumor characteristics, and surgical management (resection and reconstruction). Additionally, a further 42 patients (44 cases) were identified through a systematic Preferred Reporting Systems for Systematic Reviews and Meta-Analysis-based review of the literature searching the Medline and Embase databases. RESULTS: In total, 30 cases were classified as primary and 20 cases as recurring scalp dermatofibrosarcoma protuberans (data from 5 cases were missing). The median tumor size was 24 cm2 (interquartile range 7.8-64), and the median defect size was 55.8 cm2 (interquartile range 48-112). Recurring scalp dermatofibrosarcoma protuberans was more often associated with invasion of deeper layers and required more extensive tumor resection to achieve negative margins. Within the subgroup that was managed with peripheral and deep en face margin assessment, no recurrence was observed. Most patients required local (41. 8%) or free flap (27.8%) reconstruction after dermatofibrosarcoma protuberans resection. CONCLUSION: Whenever possible, peripheral and deep en face margin assessment-based techniques should be preferred for resection of scalp dermatofibrosarcoma protuberans because they provide superior oncological safety while preserving uninvolved tissue. Patients with locally advanced and recurring scalp dermatofibrosarcoma protuberans often require multidisciplinary treatment including neurosurgery, radiotherapy, and microvascular reconstructive surgery and should be referred to a specialized center.

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.

Surgical management of dermatofibrosarcoma protuberans.

Dermatofibrosarcoma protuberans (DFSP) is an uncommon, locally aggressive cutaneous malignancy. Complete resection is the primary treatment but there is debate over the optimal method. Wide local excision was traditionally the standard of care; however, National Comprehensive Cancer Network guidelines now recommend Mohs micrographic surgery as the preferred approach. Medical therapy with imatinib can be used in advanced or unresectable disease. This review will discuss the current management of DFSP, focusing on optimal surgical approach.

COL1A1-PDGFB Fusion Associated Fibrosarcoma of the Uterine Corpus: A Case Report and Literature Review.

Uterine collagen type 1 alpha 1 (COL1A1) and platelet-derived growth factor beta chain (PDGFB) fusion associated fibrosarcoma is a recently described entity characterized by a specific translocation t(17;22) (q22;q13) leading to the formation of COL1A1-PDGFB fusion transcripts that are typically associated with dermatofibrosarcoma protuberans. So far, only 4 cases of COL1A1-PDGFB fusion associated fibrosarcoma involving the female reproductive system have been reported in the literature. All cases showed strong diffuse expression of CD34. COL1A1-PDGFB fusion associated fibrosarcomas are aggressive tumors with a propensity for chemotherapy resistance and a poor prognosis. We are reporting the fifth case of a uterine COL1A1-PDGFB fusion associated fibrosarcoma. A 58-yr-old female presented with a large uterine mass with extension into bilateral pelvic sidewalls, mesentery of rectosigmoid colon and the vagina. A hysterectomy, bilateral salpingo-oophorectomy, and tumor debulking procedure was performed. Microscopic evaluation revealed a mitotically active cellular spindle cell neoplasm with focal osteoclast like giant cells, myxoid changes and necrosis. CD34 was diffusely and strongly positive throughout the tumor. Next-generation sequencing showed presence of the COL1A1-PDGFB fusion. The patient was treated with multiple chemotherapy regimens, however, progressed under therapy with worsening symptoms and development of extensive pelvic disease. She died of disease 13 mo after the initial diagnosis. In summary, uterine COL1A1-PDGFB fusion associated fibrosarcomas are rare tumors with aggressive clinical behavior that need to be considered in the differential diagnosis of CD34-positive uterine spindle cell neoplasms. Novel treatment options may include imatinib, a tyrosine kinase inhibitor used for treatment of advanced and unresectable dermatofibrosarcoma protuberans that was given in 1 uterine sarcoma case and showed promising initial response.