Expanding the molecular landscape of undifferentiated sarcomas of bone with a novel EWSR1-SSX3 gene fusion.

Undifferentiated sarcomas characterized by a primitive monomorphic round to spindle cell phenotype and often non-specific immunoprofile remain difficult to subclassify outside molecular analysis. The increased application of RNA sequencing in clinical practice led to significant advances and discoveries of novel gene fusions that furthered our understanding and refined classification of otherwise undifferentiated neoplasms. In this study, we report an undifferentiated round to spindle cell sarcoma arising in the femur of a 34-year-old female. The round to spindle tumor cells were arranged in short fascicles, with focal rosette formation, within a hyalinized stroma. The tumor immunoprofile included diffuse reactivity for CD99, SATB2, and TLE1 and patchy positivity for Cyclin D1, Keratin AE1/AE3, synaptophysin, and chromogranin. Other markers, such as EMA, SMA, desmin, S100, ERG, and WT1, were negative. Fluorescence in situ hybridization analysis for EWSR1 gene alterations showed a break-apart signal and targeted RNA sequencing revealed an EWSR1::SSX3 gene fusion. The patient received neoadjuvant chemotherapy followed by surgery and subsequently relapsed in less than a year with lung metastasis. Larger series are needed to determine if this fusion defines a novel subset of undifferentiated tumors or represents a genomic variant of already existing primitive round cell sarcoma categories, such as Ewing sarcoma or synovial sarcoma.

Malignant undifferentiated epithelioid neoplasms with MAML2 rearrangements: A clinicopathologic study of seven cases demonstrating a heterogenous entity.

Among mesenchymal tumors, MAML2 gene rearrangements have been described in a subset of composite hemangioendothelioma and myxoinflammatory fibroblastic sarcoma (MIFS). However, we have recently encountered MAML2-related fusions in a group of seven undifferentiated malignant epithelioid neoplasms that do not fit well to any established pathologic entities. The patients included five males and two female, aged 41-71 years old (median 65 years). The tumors involved the deep soft tissue of extremities (hip, knee, arm, hand), abdominal wall, and the retroperitoneum. Microscopically, the tumors consisted of solid sheets of atypical epithelioid to histiocytoid cells with abundant cytoplasm. Prominent mitotic activity and necrosis were present in 4 cases. In 3 cases, the cells displayed hyperchromatic nuclei or conspicuous macronucleoli, and were admixed with background histiocytoid cells and a lymphoplasmacytic infiltrate. By immunohistochemistry (IHC), the neoplastic cells had a nonspecific phenotype. On targeted RNA sequencing, MAML2 was the 3' partner and fused to YAP1 (4 cases), ARHGAP42 (2 cases), and ENDOD1 (1 case). Two cases with YAP1::MAML2 harbored concurrent RAF kinase fusions (RBMS3::RAF1 and AGK::BRAF, respectively). In 2 cases with targeted DNA sequencing, mutations in TP53, RB1 and PTEN were detected in 1 case, and PDGFRB mutations, CCNE1 amplifications and CDKN2A/2B deletion were detected in another case, which showed strong and diffuse PDGFRB expression by IHC. Of the 4 cases with detailed clinical history (median follow-up period 8 months), three developed distant metastatic disease (one of which died of disease); one case remained free of disease 3 years following surgical excision. In conclusion, we describe a heterogeneous series of MAML2-rearranged undifferentiated malignant epithelioid neoplasms, a subset of which may overlap with a recently described MIFS variant with YAP1::MAML2 fusions, further expanding the clinicopathologic spectrum of mesenchymal neoplasms with recurrent MAML2 gene rearrangements.

The novel finding of an FGFR1::TACC1 fusion in an undifferentiated spindle cell sarcoma of soft tissue with aggressive clinical course.

We report an aggressive soft tissue sarcoma with FGFR1-TACC1 fusion occurring in the thigh of an 83-year-old man. Microscopically, the tumor was composed of monomorphic spindle cells arranged in intersecting fascicles. The tumor cells showed ovoid nuclei, fine chromatin, indistinct nucleoli, and elongated eosinophilic cytoplasm. Focal increase in nuclear atypia was noted. Immunohistochemistry showed only focal rare positivity to S100, but negative to SOX10, CD34, STAT6, TLE-1, SMA, and other myogenic markers. An extensive panel of immunostains did not reveal a definite lineage of cellular differentiation. The fusion junction of the chimeric transcript involved FGFR1 exon 16 and TACC1 exon 7, which was similar to those reported in other types of neoplasms such as glioblastomas and epithelial cancers. The transcript was predicted to be in-frame and confirmed by Sanger sequencing after reverse transcriptase-polymerase chain reaction. The patient was treated by marginal excision of tumor without receiving adjuvant therapy. He experienced rapid tumor recurrence with distant metastases and succumbed at 3.5 months after presentation. The finding of FGFR1-TACC1 fusion in a high-grade, undifferentiated spindle cell sarcoma of soft tissue is novel and may offer a potential therapeutic target in the near future.

Undifferentiated and dedifferentiated soft tissue neoplasms: Immunohistochemical surrogates for differential diagnosis.

Undifferentiated soft tissue sarcomas (USTS) are described in the current World Health Organization Classification of Soft Tissue and Bone Tumours as those showing no identifiable line of differentiation when analyzed by presently available technologies. This is a markedly heterogeneous group, and the diagnosis of USTS remains one of exclusion. USTS can be divided into four morphologic subgroups: pleomorphic, spindle cell, round cell and epithelioid undifferentiated sarcomas, with this combined group accounting for up to 20% of all soft tissue sarcomas. As molecular advances enable the stratification of emerging genetic subsets within USTS, particularly within undifferentiated round cell sarcomas, other groups, particularly the category of undifferentiated pleomorphic sarcomas (UPS), still remain difficult to substratify and represent heterogeneous collections of neoplasms often representing the common morphologic endpoints of a variety of malignant tumors of various (mesenchymal and non-mesenchymal) lineages. However, recent molecular developments have also enabled the identification and correct classification of many tumors from various lines of differentiation that would previously have been bracketed under 'UPS'. This includes pleomorphic neoplasms and dedifferentiated neoplasms (the latter typically manifesting with an undifferentiated pleomorphic morphology) of mesenchymal (e.g. solitary fibrous tumor and gastrointestinal stromal tumor) and non-mesenchymal (e.g. melanoma and carcinoma) origin. The precise categorization of 'pleomorphic' or 'undifferentiated' neoplasms is critical for prognostication, as, for example, dedifferentiated liposarcoma typically behaves less aggressively than other pleomorphic sarcomas, and for management, including the potential for targeted therapies based on underlying recurrent molecular features. In this review we focus on undifferentiated and dedifferentiated pleomorphic and spindle cell neoplasms, summarizing their key genetic, morphologic and immunophenotypic features in the routine diagnostic setting, and the use of immunohistochemistry in their principal differential diagnosis, and highlight new developments and entities in the group of undifferentiated and dedifferentiated soft tissue sarcomas.

DNA Methylation Profiling for Diagnosing Undifferentiated Sarcoma with Capicua Transcriptional Receptor (CIC) Alterations.

Undifferentiated soft tissue sarcomas are a group of diagnostically challenging tumors in the pediatric population. Molecular techniques are instrumental for the categorization and differential diagnosis of these tumors. A subgroup of recently identified soft tissue sarcomas with undifferentiated round cell morphology was characterized by Capicua transcriptional receptor (CIC) rearrangements. Recently, an array-based DNA methylation analysis of undifferentiated tumors with small blue round cell histology was shown to provide a highly robust and reproducible approach for precisely classifying this diagnostically challenging group of tumors. We describe the case of an undifferentiated sarcoma of the abdominal wall in a 12-year-old girl. The patient presented with a voluminous mass of the abdominal wall, and multiple micro-nodules in the right lung. The tumor was unclassifiable with current immunohistochemical and molecular approaches. However, DNA methylation profiling allowed us to classify this neoplasia as small blue round cell tumor with CIC alterations. The patient was treated with neoadjuvant chemotherapy followed by complete surgical resection and adjuvant chemotherapy. After 22 months, the patient is disease-free and in good clinical condition. To put our experience in context, we conducted a literature review, analyzing current knowledge and state-of-the-art diagnosis, prognosis, and clinical management of CIC rearranged sarcomas. Our findings further support the use of DNA methylation profiling as an important tool to improve diagnosis of non-Ewing small round cell tumors.

Think twice before stent insertion for renal artery aneurysm with elusive etiology: a case report.

BACKGROUND: Endovascular treatment has been recognized as the first line therapy for renal artery aneurysm (RAA). However, RAA related with malignancies had been sporadically reported in the literature. Stent insertion should be contraindicated for RAAs with malignant etiology, whereas surgery be optimal. CASE PRESENTATION: A 40-year-old female underwent covered stent insertion to exclude the left RAA for suspected Takayasu arteritis in a reginal hospital. Three months later the RAA recurred with sign of threatened rupture, and the patient was transferred for salvage embolization with coils and thrombin injection. However, 20 days after the embolization procedure, multiple painful subcutaneous nodules developed in her flanks. Undifferentiated sarcoma was revealed by the pathological biopsy of the nodules. The RAA in this case was most likely related with the malignancy. CONCLUSION: Malignancy was the most likely etiology behind recurrent aneurysm in this case. Definite diagnosis is mandatory for interventional radiologists before stent insertion for treatment of RAA.

An undifferentiated sarcoma with BCOR-CCNB3 fusion transcript - pathological and clinical retrospective study.

The BCOR-CCNB3 positive sarcoma is a recently identified sarcoma morphologically and clinically similar to Ewing sarcoma in adolescents and young adults. The BCOR-CCNB3 fusion transcript originates from a paracentric inversion on the X chromosome with an in-frame fusion between the last codon of BCOR and the exon 5 of CCNB3 gene. We report morphological and molecular genetic analysis of 8 undifferentiated sarcomas positive for the BCOR-CCNB3 fusion. Six of the eight BCOR-CCNB3 positive sarcoma patients were male. Five of the eight patients were in their second decade of life (median of all patients 14 years at diagnosis). The bone marrow involvement was demonstrated in 2 of 4 patients tested. Detection of the fusion transcripts BCOR-CCNB3 in the bone marrow suggests that patients with positive findings are at high risk of the tumor progression.

Primary Renal Rhabdomyosarcoma: An Unusual Bone Metastasizing Tumor of Kidney.

Rhabdomyosarcoma (RMS) is one of the common malignant tumors in the pediatric age group. There is only a single case report of primary renal alveolar RMS. Fine needle aspiration (FNA) findings of primary renal RMS has not been reported so far. Hence we present an unusual case of primary alveolar RMS of the kidney. An 11 year old boy presented with an abdominal mass. On FNA a diagnosis of undifferentiated sarcoma and anaplastic Wilms tumor were considered. The tumor was resected and showed histopathological features of alveolar rhabdomyosarcoma. He developed multiple bony metastases and succumbed to the illness despite aggressive chemotherapy. RMS of the kidney should be considered in the differential diagnosis of children with a renal mass, and may have an aggressive clinical course with bone metastases.

Interleukin-8-producing primary cardiac undifferentiated sarcoma in a child with sustained fever.

We report the case of a 12-year-old boy with primary undifferentiated sarcoma of the left atrium. He had sustained fever during the clinical course and multiple lung and brain metastases. Chemotherapy and irradiation were ineffective; he died 41 days after hospitalization. On retrospective analysis, interleukin-8 (IL-8) was elevated; this was supported by immunohistochemistry and gene expression analysis of tumor samples. IL-8 continued to increase with tumor progression accompanied by elevated neutrophil count and C-reactive protein. IL-8 is involved in malignant tumor proliferation, migration, and angiogenesis and may have been related to the clinical condition and prognosis in the present case.

High-grade myxoinflammatory fibroblastic sarcoma: a report of 23 cases.

We describe 23 cases of high-grade myxoinflammatory fibroblastic sarcoma (MIFS). The patients were 15 women and 8 men, with the age ranging at the time of diagnosis from 39 to 93 years (mean, 64.3 years; median, 66 years). Follow-up was available for 18 patients, of whom 9 developed metastatic disease; 7 of these died. Most tumors showed a predilection for the soft tissues of the extremities, with 14 cases involving the lower limb and 5 the upper extremity. However, in both sites, the acral parts were affected in only 1 case each. Of the 4 remaining tumors, 2 were found in axilla, 1 was found in sacral area, and 1 developed in the scar on the breast, 14 years after previous excision of a mammary carcinoma and subsequent local irradiation. The tumor size ranged from 1.3 cm to as much as 30 cm in the largest dimension with a mean size of 8.3 cm. Histologically, the tumors were characterized by occurrence of 3 types of characteristic cells, including (1) lipoblast-like cells with an ample, distended, mucin-filled cytoplasm compartmentalized by a variable number of intracytoplasmic septa, thus remotely resembling soccer balls; (2) large, polygonal, bizarre ganglion-like cells similar to those seen in the Hodgkin disease, also called Reed-Sternberg-like cells. Within an ample, deeply eosinophilic cytoplasm, there was an oval nucleus with vesicular chromatin and a large, inclusion-like nucleolus. Binucleated, multinucleated, or more pleomorphic forms of these cells were also present; (3) cells with emperipolesis of variable sizes, ranging from very inconspicuous neoplastic cells containing only one to a few engulfed cells to conspicuous large ones having many inflammatory cells, usually polymorphonuclear leukocytes admixed with various numbers of some lymphoid cells, within the cytoplasm. Quite often, we found elements that combined the histologic features of all the above 3 characteristic tumor cell types. In 2 tumors, we found an additional undifferentiated spindle cell sarcoma component, whereas in another tumor, a chondrosarcomatous moiety was evident. For comparison, we studied 10 cases of pleomorphic hyalinizing angiectatic tumor (PHAT) of soft tissues. Based on the identification of morphological changes typical for MIFS within most of the cases of PHAT, we suggest that most cases of PHAT represent examples of MIFS merely having hyaline ectatic vessels.

A Modification of the American Joint Committee on Cancer Nomogram for Undifferentiated Sarcoma With External Validation and Risk Stratification.

BACKGROUND: The aim of this study is to establish a model to predict the overall survival (OS) and stratify the risk of postoperative patients with undifferentiated sarcoma. METHODS: A total of 452 postoperative patients with undifferentiated sarcoma in the trunk and extremity from the Surveillance, Epidemiology, and End Results database were enrolled as the training cohort. We collected a group of 163 undifferentiated sarcoma patients from our center as the external validation cohort. Cox proportional hazards regression model was used to screen survival-associated factors for the construction of the nomogram. Concordance-indexes (C-indexes), calibration curves, and receiver operating characteristics (ROCs) curves were applied for the discrimination and calibration of the nomogram. The cutoff value of nomogram-based total points was applied to stratify the risk of patients. RESULTS: A nomogram was developed incorporating four independent factors: age, tumor site, eighth AJCC stage, and radiotherapy. The nomogram showed good prognostic accuracy and excellent agreement in the training and validation cohort, with C-indexes of .701 (95% confidence interval [CI]: .683-.719) and .700 (95% CI: 0.659-.741), respectively. Furthermore, we identified the best cutoff value of nomogram total points (103.2) as the predicted risk and divided the patients into a high-risk group and a low-risk group. Significant differences in OS between the two groups were indicated in the training cohort and external validation cohort, showing the appreciable clinical validity and clinical utility of the nomogram (P < .001). CONCLUSION: This nomogram provides an insightful and applicable tool for individual evaluations and the distinguishment of risk for patients with undifferentiated sarcoma.

Incidental finding of an undifferentiated sarcoma during lower limb Doppler ultrasound: A case report.

Introduction: Undifferentiated sarcoma is considered a rare and aggressive type of soft tissue sarcoma with the lower extremity reported as the common site for soft tissue sarcomas. Case presentation: We present a rare incidental finding of undifferentiated sarcoma during lower limb Doppler ultrasound with a presenting symptom of right thrombotic-like calf pain in a 49-year-old female. Discussion: On ultrasound, the presented undifferentiated sarcoma appeared as a large heterogeneous, oval-shaped, soft tissue mass deeply seated in the right calf with involvement of the soleus muscle. The features on ultrasound mimicked those of a hematoma; however, the possibility of the lesion being a haematoma was promptly ruled out with the demonstration of internal vascularity on colour Doppler application. The case was then referred to a sarcoma triage multidisciplinary team for a review. Magnetic resonance imaging, computed tomography and biopsy were parts of the diagnostic workup for this case, histology confirmed the soft tissue lesion to be an undifferentiated sarcoma. Emergency above knee amputation of the right leg was performed as part of the patient's treatment. Conclusion: This case report presents a rare incidental finding of undifferentiated sarcoma encountered during lower limb Doppler ultrasound causing thrombotic-like calf pain. Sonographers are encouraged to pay necessary attention and carefully examine any adjacent and incidental soft tissue lesion during lower limb Doppler ultrasound using compression, two-dimensional imaging and colour imaging, especially those that appear with characteristic features of malignancy; urgent referral should be made of such cases to a tertiary soft tissue sarcoma centre for further evaluation and management.

Case report: The first account of undifferentiated sarcoma with epithelioid features originating in the pleura.

Undifferentiated epithelioid sarcoma (USEF) is a rare subtype of undifferentiated soft tissue sarcoma that presents unique challenges in clinical diagnosis and treatment. Here, we report a case of USEF occurring in the pleura of a 51-year-old man for the first time. Thoracoscopic examination revealed widespread nodular changes, and pathological analysis confirmed the presence of numerous epithelioid atypical cells. Immunohistochemical (IHC) analysis demonstrated an undifferentiated phenotype with distinct characteristics: epithelial membrane antigen (foci +), vimentin (+), Ki-67 (+70% +), TTF-1 (+), P53 (mutant type +90%), INI-1 (+), and CK5/6 (small foci +). Immunohistochemical examination of the tumor showed that the tumor was an undifferentiated epithelioid sarcoma. High-throughput DNA sequencing revealed pivotal mutations, including a nonsense mutation in the NF1 gene (c.641A > G(p.H214R)). and critical TP53 missense mutation (c.641A > G(p.H214R)). This TP53 mutation, with a tumor mutation burden of 16.5 Muts/Mb, signifies a high level of genomic instability, likely contributing to the rapid progression and aggressiveness of the disease. Detection of the TP53 mutation provides essential insights, indicating the disease's rapid progression and highlighting the potential for targeted therapies. Although the patient's disease progressed extremely rapidly and he tragically died within a week, we discussed the results of IHC and DNA sequencing in detail and discussed his possible treatment options. Insights gained from this case will be critical in shaping future diagnostic and therapeutic paradigms for USEF, particularly in the context of TP53 mutations.

Rapid but nondurable response of a BRAF exon 15 double-mutated spindle cell sarcoma to a combination of BRAF and MEK inhibitors.

INTRODUCTION: BRAF V600E substitution predicts sensitivity of a cancer to BRAF inhibitor therapy. The mutation is rarely found in soft-tissue sarcomas. Here we describe a case of undifferentiated spindle cell sarcoma showing primary insensitivity to standard chemotherapy and pronounced but non-sustained response to BRAF/MEK inhibitors at recurrence. CASE PRESENTATION: A 13-year-old girl was diagnosed with low-grade spindle cell sarcoma of pelvic localization, BRAF exon 15 double-mutated: c.1799T>A p.V600E and c.1819T>A p.S607T in cis-position. The tumor showed resistance to CWS-based first-line chemotherapy and was treated surgically by radical resection. Seven months after surgery the patient developed metastatic relapse with abdominal carcinomatosis. Combined targeted therapy with BRAF/MEK inhibitors afforded complete response in 1 month and was continued, though complicated by severe side effects (fever, rash) necessitating 1-2 week toxicity breaks. After 4 months from commencement the disease recurred and anti-BRAF/MEK regimen consolidation was unsuccessful. Intensive salvation chemotherapy was ineffective. Empirical immunotherapy afforded a transient partial response giving way to fatal progression with massive, abdominal cocoon-complicated peritoneal carcinomatosis. CONCLUSION: This is the first report of spindle cell sarcoma BRAF V600E/S607T double-mutated, responding to a combination of B-Raf and MEK inhibitors. Despite the low histological grade and radical surgical treatment of the tumor at primary manifestation, the disease had aggressive clinical course and the response to BRAF/MEK targeted therapy at recurrence was complete but nondurable. Empirical use of pembrolizumab provided no unambiguous evidence on the clinical relevance of immunotherapy in protein kinase -rearranged spindle cell tumors.

Recurrent mucinous carcinoma with sarcomatoid and sarcomatous mural nodules: a case report and literature review.

Ovarian mucinous tumors with sarcomatous mural nodules are rare. Sarcomatous nodules have a bad prognosis. Its diagnosis and treatment are controversial.It is still controversial whether malignant mural nodules represent a dedifferentiated form of mucinous tumors or collisional tumors. This is a case report of a 32-year-old female diagnosed with ovarian mucinous tumor recurred as a mucinous carcinoma combined with sarcomatoid and undifferentiated sarcoma mural nodules after surgery and chemotherapy. The primary lesion did not have a sarcomatous component after comprehensive sampling and repeated review, while the recurrent lesion had a predominantly sarcomatous component. The patient received a second operation and postoperative chemotherapy plus Anlotinib with no progression at 16 months of follow-up. Primary mucinous carcinoma and sarcomatous mural nodules revealed the same K-RAS mutation(c.35G>T, pG12V), TP53 mutation (c.817C>T, p.R273C), MLL2 mutation(c.13450C>T, p.R4484) and NF1 mutation(c.7876A>G, p.S2626G). We present a comprehensive analysis on morphologic characteristics, molecular detection results, clinical management, and prognosis of ovarian mucinous tumors with mural nodules of sarcomatoid and undifferentiated sarcoma. Mutation sharing between primary mucinous carcinoma and recurrent sarcomatous nodules supports monoclonal origin of primary and recurrent tumors, suggesting a tendency for sarcomatous differentiation during the progression of epithelial tumors. Malignant mural nodules represent dedifferentiation in mucinous ovarian tumors rather than collision of two different tumor types. Therefore, it is imperative to conduct comprehensive sampling, rigorous clinical examination, and postoperative follow-up in order to thoroughly evaluate all mural nodules of ovarian mucinous tumors due to their potential for malignancy and sarcomatous differentiation.

Clinical presentation, diagnostic evaluation, and management of undifferentiated/unclassified cardiac sarcoma: A case report and literature review.

This case report details a challenging instance of undifferentiated/unclassified cardiac sarcoma in a 28-year-old female, presenting with diverse symptoms like muscle weakness, shortness of breath, and hemoptysis. Diagnostic hurdles led to an initial misdiagnosis of granulomatosis with polyangiitis before discovering a sizable left atrial mass, ultimately diagnosed as high-grade undifferentiated/unclassified sarcoma. Despite initial surgical intervention, the patient's condition worsened, underscoring the complexities in managing such cases involving cardiac sarcomas. This case emphasizes the diagnostic complexities associated with primary cardiac sarcomas, particularly the challenges in achieving accurate diagnoses and formulating effective treatment strategies.

Pleomorphic undifferentiated sarcoma of urinary bladder with calcified pulmonary metastasis: A rare entity.

We report the case of a 29-year-old male who presented to us with hematuria, dysuria and bilateral flank pain. On evaluation, the patient was found to have primary pleomorphic undifferentiated sarcoma of bladder with calcified pulmonary metastasis, confirmed with computerized tomography scan and immunohistochemistry.

Pleomorphic undifferentiated sarcoma of the mediastinal thymus: A case report and literature review.

Pleomorphic undifferentiated sarcoma (PUS) of the mediastinal thymus is a rare type of cancer. In the present case report, a 67-year-old female patient presenting a mediastinal mass for >1 year was assessed for clinical characteristics, histopathological, immunohistochemical expression and gene mutation using fluorescence in situ hybridization (FISH), and relevant literature was reviewed. Histological analysis revealed nodular changes of different sizes in the thymus, which consisted of a mixture of pleomorphic and spindle cells. The pleomorphic cells with distinct atypia were giant cells and multinucleated cells with large cell sizes and frequent nuclear divisions. The spindle cells were mild to moderate atypical and arranged in a woven pattern, and nuclear division was rare. Immunohistochemical analysis indicated that vimentin was diffusively expressed in tumor cells. No amplification was found in CDX2 and MDM4 genes using the FISH analysis. In conclusion, mediastinal thymus neoplasm should be considered in the presence of PUS and it is an exclusionary diagnosis based on clinical and pathological examination of the patient.

Retroperitoneal undifferentiated pleomorphic sarcoma with total nephrectomy: a case report and literature review.

Background: Undifferentiated pleomorphic sarcoma (UPS) is a highly malignant soft tissue sarcoma with a poor prognosis and no clear effective clinical means for treatment, and there has been no significant progress in research within this field in recent years. This study aimed to investigate the epidemiology, etiology, clinical features, diagnostic modalities, various treatment modalities, and prognosis of retroperitoneal undifferentiated pleomorphic sarcoma and to contribute to the clinical management of this type of disease. In this study, we report a case of undifferentiated pleomorphic sarcoma with a primary origin in the retroperitoneum. Undifferentiated pleomorphic sarcoma occurring in the retroperitoneum is rarely reported. Case description: A 59-year-old man with abdominal distension and pain for 4 months presented to our hospital after the failure of conservative treatment. A 9.6 cm by 7.4 cm mass in the left retroperitoneum was found on a CT scan of the whole abdomen with three degrees of enhancement. After surgical treatment, the tumor and the left kidney were completely removed, and pathological examination and genetic sequencing showed an apparent undifferentiated pleomorphic sarcoma. The patient subsequently declined follow-up treatment and is currently alive and well. Conclusions: At the current level of clinical technology, the treatment of undifferentiated pleomorphic sarcoma is still in the exploratory stage, and the scarcity of clinical cases of this disease may have hindered the acquisition of clinical trials and research data for this disease. At present, the first choice of treatment for undifferentiated pleomorphic sarcoma is still radical resection. In the existing clinical studies, there are no strong data to support the effect of preoperative neoadjuvant chemoradiotherapy and adjuvant chemoradiotherapy in clinical practice. Similar to other diseases, the use of radiotherapy and chemotherapy before and after surgery may be a potential treatment for this disease in the future. Targeted therapy for this disease still needs further exploration, and we need more reports on related diseases to promote future treatment and research on this disease.

Pleomorphic type undifferentiated gastric sarcoma, report of a case.

Reports on pleomorphic type of undifferentiated sarcoma (PUS) originating from the gastrointestinal tract, especially the stomach, are extremely rare. We herein report a case of pleomorphic type undifferentiated gastric sarcoma. The patient was a 67-year-old woman. The chief complaint was upper abdominal pain. Upper gastrointestinal endoscopy, ultrasonography, and contrast-enhanced computed tomography showed two submucosal tumors at the greater curvature of the fundus and the lesser curvature of the gastric angle. Endoscopic ultrasound-guided fine-needle aspiration revealed a c-kit-negative spindle cell tumor at the greater curvature of the fundus. Total gastrectomy, splenectomy, and partial resection of the diaphragm and liver were performed. One lesion had invaded the lateral segment of the liver, left diaphragm and spleen. The postoperative course was uneventful. Histopathological and immunohistochemical examinations of the resected specimen revealed PUS. Peritoneal dissemination was detected at 8 months after surgery. However, no effective therapeutic agents were adopted for chemotherapy. The patient had poor performance status due to disease progression and underwent best supportive care. The patient died 10 months after surgery. This case highlights the imaging, histological diagnosis, and treatment strategy for PUS originating from the stomach. Surgeons should be aware of PUS as a differential diagnosis in cases with submucosal tumor of the stomach.