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ISLET-1 (ISL1) is a LIM-homeodomain transcription factor. Selective ISL1 expression is shown in neuroendocrine, non-neuroendocrine, and some soft tissue tumors including desmoplastic small round cell tumor (DSRCT). We assessed the specificity of ISL1 (clone EP283, 1:500, Cell Marque) in 288 soft tissue tumors, which included 17 DSRCTs and other histologic mimics. Positive staining threshold for ISL1 was set to >10 % of neoplastic cell nuclei at moderate intensity. ISL1 IHC was positive in 15/16 (94 %) DSRCTs with 75 % showing diffuse (>50 %) expression. ISL1 was positive in 1/10 (10 %) Ewing sarcomas (EWS), 7/13 (54 %) alveolar rhabdomyosarcoma (RMS), 14/22 (63 %) embryonal RMS, 7/14 (50 %) synovial sarcomas, 15/16 (93 %) neuroblastoma, 1/5 (20 %) Wilms tumor, 2/4 (50 %) olfactory neuroblastoma, and all 9 Merkel cell carcinomas. Other tumors, including all CIC::DUX4 sarcomas, were negative except 3/27 leiomyosarcomas, and 1 each of angiosarcoma, myxoid liposarcomas, inflammatory myofibroblastic tumor, malignant peripheral nerve sheath tumor, tenosynovial giant cell tumor, dedifferentiated LPS, and 1 ectomesenchymoma. In summary, among the soft tissue tumors tested, ISL1 is a highly sensitive but moderately specific marker for DSRCT and may be useful to distinguish from round cell mimics including EWS and CIC::DUX4 sarcomas. The oncogenic role of ISL1 in these tumors warrants further investigation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Bone and soft tissue tumors (BST) are a highly heterogeneous group largely classified by their line of differentiation, based on their resemblance to their normal counterpart in adult tissue. Yet, rendering a specific diagnosis can be challenging, primarily due to their rarity and overlapping histopathologic features or clinical presentations. Over the past few decades, seemingly histogenetic-specific gene fusions/translocations and amplifications have been discovered, aiding in a more nuanced classification, leading to well-established objective diagnostic criteria and the development of specific surrogate ancillary tests targeting these genetic aberrations (e.g., immunohistochemistry). Ironically, the same research also has revealed that some specific tumor subtypes may be the result of differing and often multiple gene fusions/translocations, but, more interestingly, identical gene fusions may be present in more than one phenotypically and biologically distinct neoplasm, sometimes with entirely different clinical behavior. Prime examples include, EWSR1::ATF1 and, less commonly, EWSR1::CREB1 gene fusions present in both clear cell sarcoma, a malignant high-grade tumor with melanocytic differentiation, and angiomatoid fibrous histiocytoma, a mesenchymal neoplasm of intermediate malignancy with a generally indolent course. Similarly, MDM2 amplification, once deemed to be pathognomonic for atypical lipomatous tumor/well differentiated and dedifferentiated liposarcoma, has been documented in a range of additional distinct tumors, including low grade osteosarcomas (e.g. low grade central and surface parosteal) and high-grade intimal sarcomas, amongst others. Such findings reinforce the importance of careful attention to morphological and clinicoradiological features and correlation with molecular testing before rendering a specific diagnosis. Future classification systems in BST neoplasms cannot be solely based on molecular events and ideally will balance morphologic features with molecular analysis. Herein, we provide a narrative literature review of the more common BST neoplasms with shared genetic events but differing demographics, morphology, immunophenotype, and clinical behavior, re-emphasizing the importance of the hematoxylin and eosin slide and the "eye" of the practicing pathologist., Competing Interests: Declaration of competing interest The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2024. Published by Elsevier Inc.)

Background: Soft tissue tumors (STTs) in adolescents are relatively rare, and their characteristics and behavior have not been well studied in this age group. The aim of this study was to describe the clinicopathologic patterns of STTs in adolescents aged 10-19 years according to the 2020 WHO classification., Method: A 10-year retrospective cross-sectional study of 632 surgical samples from adolescents was conducted at a tertiary health facility to determine the frequency, histological patterns and characteristics of STTs in this population. The data were analyzed via SPSS 23., Results: STTs accounted for 12.5% of all histologically diagnosed lesions in adolescents, with a mean age of 15 ± 2.9 years, 54.4% occurring in females and 35.4% in middle adolescents. The majority (64.56%) of STTs were benign, while malignant and intermediate-grade neoplasms accounted for 25.32% and 10.13%, respectively. Vascular tumours were the most common, followed by adipocytic and fibroblastic/myofibroblastic tumours, with hemangiomas being the most common. The most prevalent symptom was a painless mass (82.3%), with the head and neck (25.3%) being the most commonly involved body site. Most of the STTs patients presented within the first two years of occurrence (36.7%, n = 29/79). However, age, age group and sex were not significantly associated with the WHO grades of these STTs., Conclusion: This study provided valuable insights into the characteristics and behavior of STTs in adolescents, highlighting the importance of early diagnosis and management. These findings suggest that adolescent STTs affect females more than males , involve the head and neck more and are more benign, with vascular tumours being the most common type of STT in this age group., Competing Interests: Declarations. Ethics approval and consent to participate: This study utilized anonymized archived human tissues and was conducted in accordance with the World Medical Association’s Helsinki Declaration and the National Health Research Ethics Committee guidelines. The study protocol was reviewed and approved by NAUTH Human Research Ethics Committee (NAUTH HREC), Nnewi (Reference: NAUTH/CS/66/VOL.14/VER3/134/2021/036). As the study did not involve direct contact with human subjects, consent to participate was deemed unnecessary by the NAUTH HREC. A hospital permit (Reference: NAUTH/CS/66B/VOL.2/153) was also obtained from NAUTH management before commencement of this study. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

NTRK-rearranged spindle cell neoplasm is a group of tumors characterized by NTRK1/2/3 gene fusion. Recently, tumors with other kinase fusion genes were reported to exhibit similar morphologies. Herein, we discuss an adult-onset soft tissue tumor with similar histologic patterns as kinase gene fusion-related tumors but with BRAF and NRAS mutations. A female in her 40s had a 40 mm tumor with an unclear border in the soft tissue of her foot joint. Short spindle-shaped tumor cell proliferation with abundant capillaries and collagen fiber bundles were observed. The tumor infiltrated the subcutaneous adipose tissue, exhibiting a lipofibromatosis-like pattern. Immunohistochemically, the tumor cells coexpressed CD34, S-100, and BRAF V600E. Whole-exome sequencing revealed BRAF p.V600E and NRAS p.Q61K mutations. Since BRAF activation occurs in BRAF fusion gene tumors and BRAF mutations, they could share a similar mechanism in tumorigenesis. This case suggests the further expansion of kinase-related spindle cell tumors., (© 2024 Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.)

The initial approach to soft tissue tumors in children and teenagers is everyone's responsibility. While the vast majority is benign, all practitioners dread missing a malignant lesion. The first step involves taking the patient's history and performing a clinical examination. Useful information can be gained from radiographs, ultrasound imaging and MRI. If there is no diagnosis at this stage, a biopsy (preferably percutaneous) is essential because unplanned excision can have serious consequences in terms of morbidity and even mortality. This should only be undertaken at a specialized facility after careful planning by the surgeon and interventional radiologist. Once the diagnosis has been made, the case should be discussed at a tumor board meeting to benefit from multidisciplinary expertise and input. Surgery is an essential component of the treatment and must be done at the appropriate time, after potential systemic (chemotherapy, targeted therapy) or local treatment (radiation therapy). LEVEL OF EVIDENCE: Expert opinion., Competing Interests: Declaration of competing interest None., (Copyright © 2024. Published by Elsevier Masson SAS.)

The clinicopathological spectrum of undifferentiated round cell sarcomas of bone and soft tissues is expanding after the 5th edition of the WHO classification. A 23-year-old male patient presented with a lump in his left thigh of 3 months' duration. Radiological examination revealed a well-defined, solid-cystic lobulated, soft tissue lesion in the proximal medial region of his left thigh, measuring 7.7 cm in the largest dimension. The referring diagnosis was an epithelioid sarcoma. Histopathological review of the tumor sections revealed a cellular tumor composed of malignant epithelioid to focally "rhabdoid-like" cells in a variable hyalinized and myxoid stroma with geographic areas of necrosis. In addition, there were areas reminiscent of hemangiopericytomatous vasculature. By immunohistochemistry, the tumor cells were diffusely positive for CD34, focally and distinctly for pan keratin (AE1/AE3). INI1/SMARCB1 and SMARCA4 (BRG1) were diffusely positive (normal). Next-generation sequencing with a wide sarcoma panel revealed EWSR1exon8::ZBT44exon4 fusion. The present example constitutes the first malignant epithelioid tumor with a hemangiopericytomatous growth pattern, exhibiting this rare fusion. The differential diagnoses of this tumor and their corresponding immunohistochemical profile are discussed. This example highlights the value of NGS in unraveling rare fusions and in differentiating these tumors from their several mimics., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Introduction: Benign and malignant myxoid soft tissue tumors have shared clinical, imaging, and histologic features that can make diagnosis challenging. The purpose of this study is comparison of the diagnostic performance of a radiomic based machine learning (ML) model to musculoskeletal radiologists., Methods: Manual segmentation of 90 myxoid soft tissue tumors (45 myxomas and 45 myxofibrosarcomas) was performed on axial T1, and T2FS or STIR magnetic resonance imaging sequences. Eighty-seven radiomic features from each modality were extracted. Five ML models were trained to classify tumors as benign or malignant in 40 tumors and then tested with an additional 50 tumors using cross validation. The accuracy of the best ML model based on area under the receiver operating characteristic curve (AUC) was compared to the consensus diagnosis of three musculoskeletal radiologists. Correlation between radiologist confidence (equivocal, probably, consistent with) and accuracy was tested., Results: The best ML classifier was a logistic regression model (AUC 0.792). Using T1 + T2/STIR images, the ML model classified 78% (39/50) of tumors correctly at a similar rate compared to 74% (37/50) by radiologists. When radiologists disagreed, the consensus diagnosis classified 50% of tumors (7/14) correctly compared to 86% (12/14) by the ML model, though this did not reach statistical significance. Radiologists had a cumulative accuracy of 91% (30/33) when they rated their confidence 'consistent with' compared to 61% (31/51) when they rated their confidence 'equivocal/probably' (P = 0.006). For cases when radiologists rated their confidence 'equivocal/probably', the ML model had 76% accuracy (39/51)., Conclusions: A radiomic based ML model predicted benign or malignant diagnosis in myxoid soft tissue tumors similarly to the consensus diagnosis by three musculoskeletal radiologists. Radiologist confidence in the diagnosis strongly correlated with their diagnostic accuracy. Though radiomics and radiologists perform similarly overall, radiomics may provide novel diagnostic utility when radiologist confidence is low, or when radiologists disagree., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2025 Lawrenz et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Introduction: Liquid biopsy as a non-invasive method to investigate cancer biology and monitor residual disease has gained significance in clinical practice over the years. Whilst its applicability in carcinomas is well established, the low incidence and heterogeneity of bone and soft tissue sarcomas explains the less well-established knowledge considering liquid biopsy in these highly malignant mesenchymal neoplasms., Materials and Methods: A systematic literature review adhering to the PRISMA guidelines initially identified 920 studies, of whom 68 original articles could be finally included, all dealing with clinical applicability of liquid biopsy in sarcoma. Studies were discussed within two main chapters, i.e. translocation-associated and complex-karyotype sarcomas., Results: Overall, data on clinical applicability of liquid biopsy in 2636 patients with > 10 different entities of bone and soft tissue sarcomas could be summarised. The five most frequent tumour entities included osteosarcoma (n = 602), Ewing sarcoma (n = 384), gastrointestinal stromal tumour (GIST; n = 203), rhabdomyosarcoma (n = 193), and leiomyosarcoma (n = 145). Of 11 liquid biopsy analytes, largest evidence was present for ctDNA and cfDNA, investigated in 26 and 18 studies, respectively., Conclusions: This systematic literature review provides an extensive up-to-date overview about the current and potential future uses of different liquid biopsy modalities as diagnostic, prognostic, and disease monitoring markers in sarcoma., Competing Interests: Declarations. Conflict of interest: MAS has received travel grants by Alphamed Fischer, implantcast, ImplanTec, and PharmaMar, outside of the submitted work. AL has received institutional educational grants by DePuy Synthes, Alphamed, and ImplanTec, outside of the submitted work. PS has received educational grants, travel support, and honoraria for lectures by Medacta, DePuy Synthes, implantcast, outside of the submitted work. The remaining co-authors (MGS, KK, BAL, DAM) declare no conflicts of interest. Ethical approval: N/A. Informed consent: N/A., (© 2025. The Author(s).)

In total, 38 patients with cystic dorsal wrist tumours managed with surgical excision were prospectively followed up for 2 years. Tissue was examined histologically after primary surgery and at recurrence. Two distinct tissue types were found: ganglion cyst and synovial cyst., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Fewer than 5 % of soft tissue sarcomas arise in the foot and ankle. It can be difficult to distinguish between benign and malignant lesions which leads to a delay in diagnosis. Initial inappropriate procedures limit options for limb salvage and increasing rates of local recurrence. Our aim is to improve understanding of the presentation and management of these rare tumors to reduce delays in diagnosis and decrease the occurrence of inappropriate or unwarranted procedures. A prospectively maintained database of 376 new referrals to the West of Scotland regional musculoskeletal oncology service for soft tissue lesions of the foot, ankle, and lower leg over a 10-year period was analysed retrospectively. An assessment was made of patient demographics, presentation, anatomical location, diagnosis, classification, management, and outcomes for all patients. Of all new referrals, 53.5 % were diagnosed with primary benign soft tissue tumors and 16 % with primary malignant soft tissue tumors. The most common primary benign tumor in our population was schwannoma (15.9 %) and primary malignant tumor was undifferentiated sarcoma (26.7 %). In the foot alone, soft tissue sarcomas most commonly occurred in the forefoot (44.4 %). The most common presenting complaints were rest pain and focal swelling. Symptoms were present for on average 7 months prior to referral. Death from disease in sarcomas was 41.7 % over a 10 year follow up period, higher than other body areas. Soft tissue sarcomas in the foot and ankle remain a diagnostic challenge. Local biopsies should only be performed following discussion with an oncology surgeon. We have provided a management protocol in order to reduce the number of inappropriate procedures performed in this group and expedite referral to specialist centres, optimising clinical outcomes and reducing the cost of litigation to healthcare services., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 the American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.)

Objective: The purposes of this study were to assess the frequency of detection of clinically relevant findings by abdominal radiographs and abdominal ultrasound during restaging of solid, soft tissue tumours in dogs and to determine the cost per clinically relevant finding for both modalities., Materials and Methods: The medical records of 159 dogs which underwent a total of 223 restaging episodes following a diagnosis of a solid, soft tissue tumour within, or with potential for metastasis to, the abdomen were reviewed. Data collected from the sample dogs were reviewed for clinically relevant findings, including local recurrence, lymph node or intra-abdominal metastasis, and other changes that would influence prognosis or management. The clinically relevant findings were compared between abdominal radiographs and abdominal ultrasound. The cost per clinically relevant finding was calculated per modality based on current hospital costs., Results: Clinically relevant findings were observed in 158 restaging episodes. Ninety-two clinically relevant findings were detected with ultrasound alone, and 65 clinically relevant findings were detected with a combination of both modalities. Only one dog had a clinically relevant finding detected with radiographs alone. Findings were identified significantly more frequently with ultrasound than radiographs. Cost per clinically relevant finding was 495 USD (approx. 373 GBP/448 EUR) for abdominal radiographs and 323 USD (approx. 242 GBP/292 EUR) for abdominal ultrasound., Clinical Significance: Abdominal radiographs were of minimal use beyond abdominal ultrasound for restaging in this study, despite a higher cost per clinically relevant finding than abdominal ultrasound. This study does not support routine use of abdominal radiographs during routine restaging of solid, soft tissue tumours., (© 2024 British Small Animal Veterinary Association.)

Osseous and cartilaginous soft tissue tumours are a heterogenous group of neoplasms characterised by the presence of an osseous or cartilaginous component. Mineralisation of the osseous or cartilaginous component is a common finding amongst these lesions, presenting as calcification/ossification on radiological imaging. This pictorial review examines the key imaging findings and characteristics of osseous and cartilaginous soft tissue tumours with a focus on the distinguishing features which can help the radiologist to differentiate benign and malignant lesions. All examples provided are of histopathologically proven cases seen in our tertiary referral soft tissue sarcoma centre., Competing Interests: Conflict of interest The authors declare no conflict of interest., (Copyright © 2024 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Background: Moderately hypofractionated, preoperative radiotherapy in patients with soft tissue sarcomas (HYPORT-STS; ClinicalTrials.gov identifier NCT03819985) investigated a radiobiologically equivalent, moderately hypofractionated course of preoperative radiotherapy (RT) 15 × 2.85 Gy in patients with soft tissue sarcoma (STS). Here, the authors report longer term follow-up to update local control and report late toxicities, as well as functional and patient-reported outcomes., Methods: HYPORT-STS was a single-center, open-label, single-arm, prospective phase 2 clinical trial that enrolled 120 eligible adult patients with localized STS of the extremities or superficial trunk between 2018 and 2021. Patients received a 3-week course of preoperative RT followed by surgery 4-8 weeks later. End points and follow-up were analyzed from the date of surgery., Results: The median follow-up was 43 months (interquartile range, 37-52 months), and the 4-year local recurrence-free survival rate was 93%. Overall RT-related late toxicities improved with time from local therapy (p < .001), and few patients had grade ≥2 toxicities (9%; n = 8 of 88) at 2 years. These included: 2% grade ≥2 skin toxicity, 2% fibrosis, 3% lymphedema, and 1% joint stiffness. Four patients (3%) had bone fractures. Both functional outcomes, as measured by the Musculoskeletal Tumor Society Rating Scale (p < .001), and quality of life, as measured by the Functional Assessment of Cancer Therapy-General (p < .001), improved with time from treatment, and both measures were better in follow-up at 2 years compared with baseline., Conclusions: Long-term follow up suggests that moderately hypofractionated preoperative RT for patients with STS is safe and effective. Higher grade late toxicities affect a minority of patients. Late toxicities decrease over time, whereas functional outcomes and health-related quality of life seem to improve with more time from combined modality treatment., (© 2024 American Cancer Society.)

Introduction: Percutaneous cryoablation is a first-line therapeutic option for primary neoplasms and metastatic lesions of the musculoskeletal system. Treatment of abdominal wall tumors is challenging as surgical resection can be highly morbid and necessitate complex reconstructive surgery; the efficacy of cryoablation for abdominal wall tumors may be limited by inadequate posterior margins owing to the proximity of intra-abdominal organs. With laparoscopy and insufflation, peritoneal structures can be safely mobilized away from the abdominal wall, allowing for adequate deep margin freeze and visualization of the ice ball. We present two patients with abdominal wall soft tissue tumors treated with a novel approach of laparoscopic-assisted, percutaneous ultrasound-guided cryoablation., Patients and Methods: Patient 1 is a 65-year-old female with metastatic extraskeletal myxoid chondrosarcoma, stable on systemic therapy, who presented with a new soft tissue metastasis to the abdominal wall. Resection would have necessitated a highly morbid complex abdominal wall reconstruction with mesh. Patient 2 is a 35-year-old female with a large abdominal wall desmoid tumor, diagnosed after miscarriage. Resection was relatively contraindicated owing to the morbidity of a complex abdominal wall reconstruction and concerns regarding potential future pregnancies after surgery., Results: Both patients underwent procedures in the outpatient setting after discussion at multidisciplinary sarcoma tumor board. Laparoscopic enterolysis was performed to mobilize the bowel away from the abdominal wall, to allow direct visualization of the peritoneal aspect of the tumor, and to confirm adequacy of the posterior margin freeze of the lesion. Laparoscopic transversus abdominus preperitoneal (TAPP) blocks with local anesthetic were performed for postoperative pain control. Interventional radiology performed an ultrasound-guided cryoablation consisting of two freeze and thaw cycles. Both patients recovered well without complications and were without radiographic evidence of persistent or recurrent disease at 12 and 18 months postoperatively, respectively., Conclusion: We report a novel approach of laparoscopic-assisted cryoablation for the treatment of abdominal wall soft tissue tumors. This allowed for successful minimally invasive local control of these large tumors that would have otherwise required highly morbid resections with complex abdominal wall reconstruction and mesh repair., Competing Interests: Disclosure: None, (© 2024. The Author(s).)

Objectives: The revised European Society of Musculoskeletal Radiology (ESSR) consensus guidelines on soft tissue tumor imaging represent an update of 2015 after technical advancements, further insights into specific entities, and revised World Health Organization (2020) and AJCC (2017) classifications. This second of three papers covers algorithms once histology is confirmed: (1) standardized whole-body staging, (2) special algorithms for non-malignant entities, and (3) multiplicity, genetic tumor syndromes, and pitfalls., Materials and Methods: A validated Delphi method based on peer-reviewed literature was used to derive consensus among a panel of 46 specialized musculoskeletal radiologists from 12 European countries. Statements that had undergone interdisciplinary revision were scored online by the level of agreement (0 to 10) during two iterative rounds, that could result in 'group consensus', 'group agreement', or 'lack of agreement'., Results: The three sections contain 24 statements with comments. Group consensus was reached in 95.8% and group agreement in 4.2%. For whole-body staging, pulmonary MDCT should be performed in all high-grade sarcomas. Whole-body MRI is preferred for staging bone metastasis, with [ 18 F]FDG-PET/CT as an alternative modality in PET-avid tumors. Patients with alveolar soft part sarcoma, clear cell sarcoma, and angiosarcoma should be screened for brain metastases. Special algorithms are recommended for entities such as rhabdomyosarcoma, extraskeletal Ewing sarcoma, myxoid liposarcoma, and neurofibromatosis type 1 associated malignant peripheral nerve sheath tumors. Satisfaction of search should be avoided in potential multiplicity., Conclusion: Standardized whole-body staging includes pulmonary MDCT in all high-grade sarcomas; entity-dependent modifications and specific algorithms are recommended for sarcomas and non-malignant soft tissue tumors., Clinical Relevance Statement: These updated ESSR soft tissue tumor imaging guidelines aim to provide support in decision-making, helping to avoid common pitfalls, by providing general and entity-specific algorithms, techniques, and reporting recommendations for whole-body staging in sarcoma and non-malignant soft tissue tumors., Key Points: An early, accurate, diagnosis is crucial for the prognosis of patients with soft tissue tumors. These updated guidelines provide best practice expert consensus for standardized imaging algorithms, techniques, and reporting. Standardization can improve the comparability examinations and provide databases for large data analysis., Competing Interests: Compliance with ethical standards. Guarantor: The scientific guarantor of this publication is Univ.-Prof. Priv.-Doz. Dr. I.M.N.H. Conflict of interest: A.B. is a member of the European Radiology Editorial Board. He has not taken part in the review or selection process of this article. The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article. Statistics and biometry: No complex statistical methods were necessary for this paper. Informed consent: Written informed consent was not required for this study because patients were not involved. Ethical approval: Institutional Review Board approval was not required because patients were not involved. Study subjects or cohorts overlap: Study subjects or cohorts have not been previously reported. Methodology: Expert consensus is performed by a Delphi process Perspective: not applicable Study design: not applicable Location: multicentre study, (© 2024. The Author(s).)

In the 2020 5th edition of the World Health Organization classification of soft tissue and bone tumours a major reorganization of Undifferentiated Small Round Cell Sarcomas (USRCS) took place based on the underlying molecular features. The classification now recognizes Ewing sarcoma, round cell sarcoma with EWSR1-non-ETS fusions, CIC-rearranged sarcoma and sarcoma with BCOR alterations. The focus on these genetic alterations highlights the importance of molecular techniques in the diagnosis of these entities. Knowledge of these features can drastically reduce the time to diagnosis and avoid potential misdiagnosis. Molecular diagnostic capabilities should not be limited to an overall small number of centres worldwide as is reflected by the WHO's recognition of 'essential' and 'desirable' diagnostic criteria. A good knowledge of the usual histomorphology, uncommon variants and diagnostic pitfalls remains essential even in centres with access to a full molecular testing arsenal. This review aims to give an overview of the current classification of USRCS not by going over each entity, but instead going over the molecular, morphological, immunophenotypic and clinical features step by step to allow easy comparison of these features between the separate entities., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Fibroblastic and myofibroblastic neoplasms represent about 12% of pediatric soft tissue tumors. Most of these neoplasms in children are either benign or locally aggressive with rare metastasis, while malignant cases are uncommon. Diagnosing these tumors is challenging due to overlapping morphologies and the limited utility of immunohistochemistry. Advances in molecular techniques, especially RNA sequencing, have improved our understanding of the molecular drivers of these tumors, leading to better classification. Key molecular alterations, such as RTK and MAPK activation, are central in the development of tumors like infantile fibrosarcoma (IFS) and inflammatory myofibroblastic tumors (IMT). The identification of alternative fusions in IFS and IMT underscores the importance of an integrated diagnostic approach. Furthermore, new RTK-driven lesions, now included in the WHO's "NTRK-rearranged mesenchymal neoplasms", have been identified. This review provides an update on recent findings in RTK-driven myofibroblastic tumors and highlights novel entities still in need of classification., Competing Interests: Declarations. Ethics approval: This article does not contain any studies with human participants or animals performed by any of the authors. Consent to participate: N/A. Consent for publication: N/A. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Pediatric angiosarcoma of soft tissue, an extremely rare entity, remains poorly understood from a genetic standpoint. Herein, we present the case of a previously healthy 17-year-old girl with acute left hip pain. Subsequent magnetic resonance imaging revealed a 21.8 cm left pelvic sidewall mass with heterogeneous enhancement and multiple lung nodules. Biopsy of the tumor showed an infiltrative, hemorrhagic neoplasm composed primarily of atypical spindle to epithelioid cells. Focal vasoformative architecture was appreciated. Immunohistochemically, the tumor cells were strongly positive for CD31, ERG, and FLI-1, supporting the diagnosis of angiosarcoma. Genetic analysis identified a novel TEK::GAB2 gene fusion. TEK belongs to the angiopoietin receptor family, and its fusion with GAB2 is predicted to mediate tumorigenesis. This report expands the current knowledge on the spectrum of gene rearrangements of angiosarcoma., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Introduction: Soft tissue tumors are complex neoplasms requiring accurate diagnosis, often through fine needle aspiration (FNA). The World Health Organization (WHO) classification system aims to standardize cytopathological diagnoses and assess the risk of malignancy (ROM) for these tumors., Materials and Methods: This retrospective study reviewed cytological specimens from January 2022 to June 2023. Samples were categorized using the WHO classification into 6 categories: nondiagnostic, benign, atypical, soft tissue neoplasm of uncertain malignant potential, suspicious for malignancy (SFM), and malignant. Histopathological correlation was performed, and ROM, sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were calculated., Results: A total of 203 samples were analyzed: 62.5% benign, 13.8% SFM, and 9.9% malignant. ROMs were 33.3% (nondiagnostic), 1.2% (benign), 40% (atypical), 25% (soft tissue neoplasm of uncertain malignant potential), 80% (SFM), and 100% (malignant). Histopathological correlation was available for 117 cases. Sensitivity and diagnostic accuracy were highest (77.3% and 93.9%) when SFM and malignant categories were combined as positive for malignancy. Specificity was highest (100%) when only malignant cases were considered positive. The interobserver agreement was moderate (Cohen's kappa 0.45)., Conclusions: The WHO classification system for soft tissue cytopathology improves diagnostic accuracy and standardizes reporting. It effectively categorizes soft tissue tumors and guides clinical management, though further refinement is needed for broader applicability., (Copyright © 2024 American Society of Cytopathology. Published by Elsevier Inc. All rights reserved.)

BACKGROUND Limb-girdle muscular dystrophy recessive 1 (LGMDR1) is an autosomal recessive degenerative muscle disorder characterized by progressive muscular weakness caused by pathogenic variants in the CAPN3 gene. Desmoplastic small round cell tumors (DSRCT) are ultra-rare and aggressive soft tissue sarcomas usually in the abdominal cavity, molecularly characterized by the presence of a EWSR1::WT1 fusion transcript. Mouse models of muscular dystrophy, including LGMDR1, present an increased risk of soft tissue sarcomas. However, the DSRCT risk and general cancer risk in patients with LGMD is unknown. Here, we delineate the clinical, molecular, and genetic findings of a patient with LGMDR1 who developed a DSRCT. CASE REPORT The patient was a boy who was diagnosed at the age of 9 years with LGMDR1, caused by the biallelic pathogenic variants NP&#95;000061.1:p.(Arg448Cys) and NP&#95;000061.1:p.(Thr184ArgfsTer36) in CAPN3. At 17 years of age, a pathologic soft tissue mass was found in the right pelvis. Immunostaining was positive for Desmin and negative for Myogenin and MyoD1, and RNA sequencing showed a EWSR1::WT1 fusion transcript, confirming the diagnosis of DSRCT. The patient relapsed after 1 year and, following a second relapse, he was started on palliative treatment. No germline variants in childhood cancer predisposition genes were detected by whole genome sequencing. CONCLUSIONS We describe a patient with LGMDR1 who developed a DSRCT. Since associations between LGMD and pediatric cancer are hitherto unknown, further studies are warranted, as little information is currently published about the pediatric cancer risk in this patient group.

Case: We present the case of a 73-year-old female with an acromioclavicular joint cyst associated with atypical, exquisite, progressive pain, and imaging findings concerning for neoplastic etiology. She underwent en bloc resection of the trapezium containing this cystic mass and distal clavicle. Surgical pathology demonstrated findings consistent with a large ganglion cyst without evidence of malignancy., Conclusion: Our case serves to emphasize the importance of stepwise evaluation and appropriate treatment of such cysts while utilizing appropriate principles of oncologic resection in cases where a neoplastic etiology is considered., Competing Interests: Declarations. Ethics approval and consent to participate: IRB approval was not necessary given the nature of the case report. Consent for publication: The patient described in this case was informed that data concerning her case would be submitted for publication and was appropriately consented. Competing interests: The authors declare no competing interests. Disclosures: The authors have no financial interests in any of the products or techniques mentioned and have received no external support related to this study. No funding was received for this study., (© 2024. The Author(s).)

Background/aim: Cryoablation is a new, minimally invasive option for local tumor therapy that is attracting attention due to its potential interactions with the immune system. The purpose of this study was to evaluate the efficacy of cryoablation for local control of bone and soft tissue lesions, to elucidate risk factors for recurrence, and to clarify histological changes., Patients and Methods: Participants comprised 25 patients who underwent cryoablation for 53 discrete lesions of bone or soft tissue recurrence after resection or as metastases of cancer or sarcoma. Local progression-free survival was evaluated after completion of cryoablation. The histology of tumor tissues resected after cryoablation was assessed for seven cases., Results: Local progression-free survival rates were 88.1% at 1 year and 79.7% at 2 and 3 years. Risk of local progression was significantly higher for recurrent lesions after resection, and for lesions ≥4.0 cm in diameter than for metastatic lesions, or lesions <4.0 cm, respectively (p<0.05 each). In a subgroup analysis of bone lesions, lesions with an extraskeletal component tended to be associated with worse local recurrence-free survival than those without an extraskeletal component. On histological examination, tissue in the ablated area was completely necrotic. In the border area between ablated and non-ablated areas, CD68-positive cells including CD16-M1-like and CD204-positive M2-like cells were more frequently observed than T cells., Conclusion: Cryoablation has shown good anti-tumor efficacy across various tumor types, including those affecting the bone. However, local control was inadequate for recurrent lesions and tumors larger than 4.0 cm in diameter. Further analysis of the relationship between macrophages and cryoablation is needed and may provide critical insights into achieving a more effective anti-tumor response., (Copyright © 2024 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Objective: To depict histological and imaging features of myoepithelial carcinoma of the bone and soft tissue., Materials and Methods: We retrospectively examined histological features in 22 patients with myoepithelial carcinoma of the bone (4 patients) and soft tissue (18 patients) at a single institution. Imaging analysis of 15 patients (bone, 3 patients; soft tissue, 12 patients;) with preoperative images involved classifying lytic bone lesions via the modified Lodwick-Madewell classification; the growth patterns of soft tissue lesions were classified as well-defined, focally invasive, or diffusely invasive., Results: Local recurrence occurred in eight out of 22 patients (36.3%). Four of 22 patients (18.2%) had metastasis at presentation, whereas 11 of 22 patients (50.0%) had distant metastasis during follow-up. Severe cytological pleomorphism was observed in 14 of 22 patients (63.6%), and 10 of 22 tumors (45.5%) showed ≥ 10 mitoses/10 high-power fields. Vascular invasion was observed in 10 of 22 patients (45.5%). Extracapsular/extraskeletal infiltration into the surrounding tissues was assessed in 20 patients, with 14 of them (70%) showing infiltration beyond the tumor border. Regarding imaging of bone lesions, two patients had Ludwick type IIIB, whereas one patient had type II. The growth pattern of soft tissue lesions was well-defined in two patients (16.7%), focally invasive in seven patients (58.3%), and diffusely invasive in three (25.0%) out of 12 patients., Conclusion: Myoepithelial carcinoma of the bone and soft tissue presents high risk of local recurrence and distant metastasis. Histological and imaging features might be important to understand the aggressive behavior of the tumor., (© 2024. The Author(s), under exclusive licence to International Skeletal Society (ISS).)

Articular masses comprise various disease entities including benign or malignant proliferative processes and other non-neoplastic processes such as infection, deposition diseases, vascular malformations, and other lesions. Many diseases that lead to intra-articular or para-articular masses have distinct imaging features, particularly on MRI. Radiologists can localize masses to the joint space by knowing the articular anatomy and can reach a suggested diagnosis by looking at precise imaging findings. In this review article, we first define the concept of articular space (intraarticular, para-articular) and the normal joint anatomy and histology. We provide a general and comprehensive approach for evaluation of articular lesions on MRI. We then describe specific imaging and histologic features of typical benign and malignant soft tissue articular neoplasms and some non-neoplastic mimickers; and provide a radio-pathologic correlation of the different described entities., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

With the increasing use of next generation sequencing in soft tissue pathology, particularly in neoplasms not fitting any World Health Organization (WHO) category, the spectrum of EWSR1 fusion-associated soft tissue neoplasms has been expanding significantly. Although recurrent EWSR1::ATF1 fusions were initially limited to a triad of mesenchymal neoplasms including clear cell sarcoma of soft tissue, angiomatoid fibrous histiocytoma and malignant gastrointestinal neuroectodermal tumor (MGNET), this family has been expanding. We herein describe 4 unclassified extra-abdominal soft tissue (n = 3) and bone (n = 1) neoplasms displaying epithelioid and round cell morphology and carrying an EWSR1::ATF1 fusion. Affected were 3 males and 1 female aged 20-56 years. All primary tumors were extra-abdominal and deep-seated (chest wall, mediastinum, deltoid, and parapharyngeal soft tissue). Their size ranged 4.4-7.5 cm (median, 6.2). One patient presented with constitutional symptoms. Surgery with (2) or without (1) neo/adjuvant therapy was the treatment. At last follow-up (8-21 months), 2 patients developed progressive disease (1 recurrence; 1 distant metastasis). The immunophenotype of these tumors is potentially misleading with variable expression of EMA (2 of 3), pankeratin (2 of 4), synaptophysin (2 of 3), MUC4 (1 of 3), and ALK (1 of 3). All tumors were negative for S100 and SOX10. These observations point to the existence of heretofore under-recognized group of epithelioid and round cell neoplasms of soft tissue and bone, driven by EWSR1::ATF1 fusions, but distinct from established EWSR1::ATF1-associated soft tissue entities. Their overall morphology and immunophenotype recapitulate that of the emerging EWSR1/FUS::CREB fusion associated intra-abdominal epithelioid/round cell neoplasms. Our cases point to a potentially aggressive clinical behavior. Recognizing this tumor type is mandatory to delineate any inherent biological and/or therapeutic distinctness from other, better-known sarcomas in the differential diagnosis including sclerosing epithelioid fibrosarcoma., Competing Interests: Declarations. Ethical approval: Samples were used in accordance with ethical guidelines for the use of retrospective tissue samples provided by the local ethics committee of the Friedrich-Alexander University Erlangen-Nuremberg (ethics committee statements 24.01.2005 and 18.01.2012). Conflict of interest: The senior author of this study is the Editor-in-Chief of Virchows Archiv. The other authors declare no competing interests., (© 2024. The Author(s).)

Ossifying fibromyxoid tumor (OFMT) is a rare soft tissue neoplasm of uncertain histogenesis, primarily arising in subcutaneous tissues of the extremities, head and neck, or trunk. Most cases present as well-circumscribed masses with a characteristic morphologic appearance, comprising cytologically bland ovoid cells with fibromyxoid stroma, a peripheral rim of metaplastic bone, and lobulated architecture. Nevertheless, tumors displaying unusual morphologic characteristics pose significant diagnostic challenges, requiring the detection of a pathogenic fusion for a definitive diagnosis. The majority of OFMTs exhibits PHF1 gene rearrangements. Herein, we present six cases of molecularly confirmed OFMTs with uncommon histomorphologic features, including the absence of myxoid stroma, extensive chondroid differentiation, prominent clear cell morphology, collagen entrapment, interdigitating fibrocollagenous and fibromyxoid stromal elements, and conspicuous red blood cell extravasation. One case harbored a novel fusion (EPC1::SUZ12). This study emphasizes the broad range of morphologic manifestations that can be encountered in OFMT and the crucial role of molecular testing in establishing a conclusive diagnosis in such cases., Competing Interests: Declarations: The authors confirm that the accepted principles of ethical and professional conduct have been followed in the present study. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Recently, a new World Health Organization Reporting System for Soft Tissue Cytopathology (WHO System) was introduced. To analyze the value of this system, routine fine-needle aspiration soft tissue tumor (STT) cases were reviewed., Methods: Cytology samples of STTs collected between 1954 and 2022 at the Institut Curie were used (2214 cases, including 1376 primary tumors). All specimens were classified according to the predominant cytomorphological pattern and the WHO System. The diagnostic accuracy and risk of malignancy (ROM) in each category were calculated., Results: Final diagnoses revealed 1236 malignancies and 978 benign or low-risk tumors. The original cytological evaluation led to 21 false-negative results (0.85%) and 29 false-positive results (1.17%). Sensitivity, specificity, positive predictive value, and negative predictive value were 98.3%, 92.1%, 97.5%, and 94.2%, respectively. Overall diagnostic accuracy was 94.2%. The ROM calculated according to the WHO System was 29.87%, 2.49%, 39.62%, 51.43%, 68.42%, and 97.69% in the nondiagnostic, benign, atypical, soft tissue neoplasm of uncertain malignant potential, suspicious for malignancy, and malignant categories, respectively; however, it varied broadly depending on the morphological pattern (62.78% in spindle cell tumors, 84.58% in myxoid tumors, 3.00% in lipomatous tumors, 78.15% in epithelioid tumors, 94.26% in pleomorphic tumors, and 100% in round cell tumors)., Conclusions: Cytology of STTs is a powerful diagnostic method. Some cytological patterns overlap in different morphological groups, and the possibility of false-negative and false-positive diagnoses may persist. This analysis evidenced utility of the WHO System, especially when combined with morphological pattern assessment. Subclassification in particular diagnostic categories allowed for calculation of the ROM, which is crucial for optimal patient management., (© 2024 American Cancer Society.)

Accurate classification of soft tissue neoplasms of the skin and subcutis can be challenging given the sometimes significant histomorphologic and immunohistochemical overlap between the entities that comprise this ever-expanding category of tumors. With the benefit of continually emerging adjuncts to histologic diagnosis, pathologists have a number of tools at their disposal for navigating this group of neoplasms. This article aims to review recent immunohistochemical and molecular updates in the diagnosis of cutaneous soft tissue neoplasms., (Copyright © 2022. Published by Elsevier Inc.)

During the past decate, Chinese pathologists have made remarkable achievements in the area of soft tissue tumors. They have not only done in-depth researches in selected entities like liposarcoma and round cell sarcomas, but have also issued expert consenses and guideline, as well as published professional books and translation books, with purpose to comprehensively improve the level of diagnosis nationwide.

Objective: To evaluate the clinical efficacy of ultrafast dynamic contrast-enhanced (DCE)-MRI using a compressed sensing (CS) technique for differentiating benign and malignant soft-tissue tumors (STTs) and to evaluate the factors related to the grading of malignant STTs., Materials and Methods: A total of 165 patients (96 male; mean age, 61 years), comprising 111 with malignant STTs and 54 with benign STTs according to the 2020 WHO classification, underwent DCE-MRI with CS between June 2018 and June 2023. The clinical, qualitative, and quantitative parameters associated with conventional MRI were also obtained. During post-processing of the early arterial phase of DCE-MRI, the time-to-enhance (TTE), time-to-peak (TTP), initial area under the curve at 60 s (iAUC60), and maximum slope were calculated. Furthermore, the delayed arterial phase parameters of DCE-MRI, including K trans , K ep , V e , and iAUC values and time-concentration curve (TCC) types, were determined. Clinical and MRI parameters were statistically analyzed to differentiate between benign and malignant tumors and their correlation with tumor grading., Results: According to logistic regression analysis, the TTE value ( P < 0.001) of the early arterial phase and V e ( P = 0.039) and iAUC ( P = 0.006) values of the delayed arterial phase, as well as age, location, peritumoral edema, and contrast heterogeneity on conventional MRI, were significant ( P = 0.001-0.015) in differentiating benign and malignant tumors. Among all the quantitative parameters, the TTE value had the highest accuracy, with an area under the receiver operating characteristic curve of 0.902. The grading of malignant tumors was significantly correlated with peritumoral edema; CE heterogeneity; visual diffusion restriction; minimum and mean ADC; TTP, K ep , and V e values; and the TCC graph (all P < 0.05)., Conclusion: Among the quantitative parameters obtained using ultrafast DCE-MRI, early arterial phase TTE was the most accurate for distinguishing between benign and malignant tumors., Competing Interests: In Sook Lee, who holds respective positions on the Section Editor of the Korean Journal of Radiology, was not involved in the editorial evaluation or decision to publish this article. The remaining authors have declared no conflicts of interest., (Copyright © 2025 The Korean Society of Radiology.)

The purpose of this article is to give a systematic approach to the ultrasound evaluation of superficial soft-tissue masses. The knowledge of proper technique in image acquisition, the characteristic sonographic appearances of the most common masses, their potential pitfalls, and the location of the lesions can help establish a confident diagnosis. Where the sonographic features of the masses are inconclusive, a percutaneous biopsy is effective in establishing the definitive diagnosis., Competing Interests: Disclosure The authors have nothing to disclose., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Fine-needle aspiration specimens from soft tissue tumors are complicated by lack of tissue architecture and limited material for ancillary testing. There are little data on the feasibility of next-generation sequencing techniques for fusion detection on soft tissue cytology specimens. This study explored the role of an anchored multiplex polymerase chain reaction (PCR)-based gene fusion assay in aiding the diagnosis of mesenchymal neoplasms on cytology samples., Methods: The laboratory information system was queried for cytology specimens that had undergone testing by anchored multiplex PCR. After exclusion of epithelial and hematolymphoid neoplasms, clinical and pathologic information was collected on the remaining cases., Results: There were 1609 cytology specimens tested with anchored multiplex PCR. Of these, 48 (3%) were cytology specimens from mesenchymal tumors. Anchored multiplex PCR was positive for a reportable fusion transcript in 14 of 48 cases (29%); there was no fusion detected in 32 cases (67%), and there was insufficient tissue for analysis in two cases (4%). The detectable fusion partners included ALK (n = 4), STAT6 (n = 4), EWSR1 (n = 3), and one each of SS18, YAP1, and PHF1. Of the cases in which a fusion partner was detected, eight of 14 were disease-defining on cytology preparation, and six of 14 provided molecular confirmation of a metastatic focus of a previously diagnosed tumor., Conclusions: The anchored, multiplex PCR-based gene fusion assay is a powerful orthogonal tool in helping diagnose mesenchymal neoplasms on cytology specimens. The material obtained for cytologic analysis yields sufficient quality/quantity of tissue in the majority of cases tested., (© 2024 American Cancer Society.)

Mesenchymal neoplasms of the kidney present challenges because they are uncommon, and because perinephric soft tissue biopsies are sometimes submitted as "kidney" masses, causing diagnostic confusion. Here, the author thoroughly reviews mesenchymal neoplasms of the kidney, including metanephric stromal tumor, classic and cellular congenital mesoblastic nephroma, anaplastic sarcoma and clear cell sarcoma of the kidney, malignant rhabdoid tumor, PEComa/angiomyolipoma, and anastomosing hemangioma. The author also discusses perinephric myxoid pseudotumor of fat, as well as diagnostic pitfalls presented by well-differentiated/dedifferentiated liposarcoma and sarcomatoid carcinoma., Competing Interests: Disclosure The author reports no conflicts of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Intravascular papillary endothelial hyperplasia (IPEH), also known as Masson's tumor, is an uncommon exuberant form of organizing thrombus that may occur within a vessel, vascular tumor, or hematoma and may change the imaging appearance to mimic an aggressive process. It must be distinguished pathologically from angiosarcoma. They have been most commonly reported within superficial soft tissue tumors, and rapid growth and effect on bone are rarely described. We present a case of a patient with a soft tissue hemangioma with IPEH with intraosseous extension that presented with a pathologic fracture of her right humerus with an aggressive appearing osseous lesion. CT and MRI demonstrated a multifocal ill-defined soft tissue mass throughout the right upper extremity with underlying cortical tunneling and scalloping of the proximal humerus. Similar imaging findings were also present in the distal humerus and ipsilateral scapula and evolved during her hospitalization. Following percutaneous biopsy revealing hemangioma with features of papillary endothelial hyperplasia with intraosseous extension, the patient died in the ICU secondary to unrelated septic shock. Diagnosis was confirmed at autopsy. Primary and secondary IPEH have been generally characterized as well-defined solitary masses, most often in the superficial soft tissues. This case of a deep soft tissue hemangioma with type II IPEH, intraosseous extension, and imaging findings of regional multicompartmental involvement is very unusual. Reporting of this case in the literature should be beneficial for pathologic correlation with similar confounding masses as well as propose a possible mechanism for intraosseous extension of soft tissue hemangiomas., Competing Interests: Declarations. Consent to participate: Informed consent was obtained from the subject described in this report. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s).)

Context: Soft tissue neoplasms are infrequent in children with sarcomas accounting for approximately 7% of all pediatric malignancies. Morphologic diagnosis is challenging due to overlapping features. Subtyping and categorization of these lesions are difficult on fine-needle aspiration cytology (FNAC) alone owing to tumor heterogeneity and limited material in some cases. Tru-cut biopsies obtain adequate tumor tissue for ancillary studies besides conventional histology., Aim: The study aims to explore the role of tru-cut biopsy to arrive at a definitive diagnosis. The study also highlights the correlation between FNAC and histopathology on tru-cut biopsy besides explaining the significance of a panel of immunohistochemistry (IHC) markers for histological categorization and subtyping., Materials and Methods: A total of 61 children from infancy to 18 years were included in the study. Closed biopsy procedures like FNAC and tru-cut biopsy were performed, and the tru-cut biopsy specimen was subjected to a panel of immunohistochemical markers., Results: Fisher's exact test for sensitivity and specificity towards detection of malignancy was 83% and 86%, respectively for FNAC. For tru-cut biopsy, sensitivity was 94% and specificity was 91%. The two-sided P value (<0.0001) was extremely significant. Cohen's Kappa coefficient value for tru-cut biopsy was 0.772 suggesting a substantial strength of agreement. Tru-cut with IHC had a Kappa value of 0.866 suggesting greater agreement with histopathology., Conclusion: Tru-cut biopsy is a simple, safe, and reliable adjunct to the FNAC. Instead, immunohistochemistry enhances the diagnostic accuracy., Competing Interests: None

In the past decade, several emerging bone and soft tissue neoplasms of the head and neck region have been described in the literature, including GLI1-altered mesenchymal tumors, (intraosseous) rhabdomyosarcoma with TFCP2 fusion, and adamantinoma-like Ewing sarcoma. This review provides a summary of the clinical features, histologic characteristics, immunoprofile, key diagnostic features, and differential diagnoses of these emerging entities. Notably, all three entities show epithelioid morphology and cytokeratin immunopositivity, highlighting the need to consider these mesenchymal neoplasms in the differential diagnoses of cytokeratin-positive epithelioid tumors in the head and neck region. Appropriate workups including detection of the characteristic molecular alterations are essential for the correct diagnosis., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

BACKGROUND Elastofibroma dorsi is a rare, benign soft-tissue tumor, emerging in the subscapular area and exhibiting higher prevalence in elderly women. Despite its slow growth rate and asymptomatic nature in most patients, elastofibroma can cause swelling, pain, and discomfort during shoulder movements. Imaging and histopathologic data combined with a detailed history are essential to exclude malignancies and provide suitable treatment. CASE REPORT This report describes the case of a 78-year-old man with an incidental finding of elastofibroma dorsi, presenting as an asymptomatic left subscapular mass. Physical examination revealed the mass, the presence of which was later confirmed through an MRI scan. The tumor was surgically excised without any postoperative complications. Histopathologic findings from a biopsy supported the diagnosis of elastofibroma dorsi, showing an abundance of thick and irregular elastic fibers, giving a "rope-like" appearance in hematoxylin and eosin stain. Additionally, Verhoeff-Van Gieson stain highlighted the elastic fibers, making their characteristic arrangement and appearance evident. The patient was then discharged from our hospital and made a complete recovery. CONCLUSIONS Despite its benign nature and rarity, elastofibroma dorsi should be included in the differential diagnosis of subscapular masses. Proper imaging and histopathological examination are crucial for a definitive diagnosis, to ensure that patients receive the appropriate and necessary treatment and guidance. Furthermore, additional research is needed to completely clarify the pathophysiologic mechanism responsible for the development of elastofibroma dorsi.

Background: Soft tissue sarcomas (STS) pose challenges in management due to large defects following wide resection. Reconstructive options are often limited, especially in patients with large circular defects below the gluteal region. This article addresses the question of how to effectively reconstruct such defects while minimizing donor-site morbidity. We present our experience with using an L-shaped combined scapular and parascapular flap after STS resection, highlighting the novelty of employing indocyanine green (ICG) angiography to ensure optimal blood flow and surgical safety., Methods: We retrospectively reviewed patients who underwent STS resection and immediate reconstruction using an L-shaped scapular and parascapular combined flap between October 2022 and April 2024. The feasibility of the procedure was assessed by analyzing the patient demographics, tumor characteristics, defect and flap sizes, operative time, and postoperative outcomes, including donor-site complications and shoulder function., Results: Six patients underwent reconstruction using an L-shaped combined flap with no donor-site complications or significant shoulder dysfunction. The average sizes were 15.7 × 13.7 cm for the defect, 20 × 7 cm for the scapular flap, and 23 × 7.3 cm for the parascapular flap. The average operative time was 7 h and 9 min. The average follow-up period was 10.2 months. Except for one case of partial flap necrosis, all flaps survived completely, highlighting the reliability of the procedure., Conclusion: L-shaped combined scapular and parascapular flaps are promising reconstructive techniques for large surface defects after STS resection with low donor-site morbidity and preservation of shoulder function. The novel application of these flaps for large circular defects below the gluteal region, combined with the use of ICG angiography to ensure flap viability and enhance surgical safety, are key contributions of this study., (© 2024 Wiley Periodicals LLC.)

Mantle cell lymphoma (MCL) is frequently diagnosed at advanced stages and is characterized by multiple extranodal sites of disease, most notably the bone marrow, peripheral blood, and gastrointestinal tract. Historically the prognosis of mantle cell lymphoma has been poor with median survival of four to five years. With new treatment regimens, however, patients have been able to achieve prolonged remissions and require special attention while being evaluated for relapse. This report describes four patients treated for stage IV mantle cell lymphoma at the University of Miami who developed soft tissue relapse presenting as non-tender large masses of the extremities, including one patient who presented without associated nodal involvement. Average time to soft tissue relapse was 99 months (range: 28-240) following initial diagnosis. Providers who care for patients with mantle cell lymphoma should be aware of soft tissue lesions as a presentation of mantle cell lymphoma that merits evaluation for disease relapse., (© 2024. The Author(s).)

Objective: This study aimed to assess the complication rate during and 24 hours after cryoablation in lung, bone, and soft tissue tumors., Methods: We reviewed complications in a total of 85 consecutive patients who underwent cryoablation using a liquid nitrogen-based system in various lesions between April 2017 and October 2022. There were no liver and renal lesions. Complications were categorized using the Society of Interventional Radiology classification., Results: Eighty-five patients were treated for 96 lesions in the bone (36.4%; 35 of 96), lung (18.8%; 18 of 96), and soft tissue (44.8%; 43 of 96). The primary technical success rate was 97.7% (83 of 85). The total grade 2 and 1 complication rates were 5.2% (5/96) and 20.8% (20/96), respectively. Two patients had asymptomatic pulmonary embolisms incidentally noted at the 24-hour follow-up computed tomography (grade 2). The most frequent complications were simple and hemorrhagic pleural effusions (18.7%; 18 of 96). Lung procedures had the highest complication rate, where 13 patients (72.2%; 13 of 18) reported complications, including 2 cases of symptomatic hydropneumothorax requiring drainage (grade 2) and an additional 2 days of hospital stay. Eight patients (24.2%; 8 of 33) with bone lesions and 4 (9.3%; 4 of 43) with soft tissue lesions experienced complications., Conclusion: Cryoablation using a liquid nitrogen-based system is safe, with only minor complications observed., Advances in Knowledge: This study provides data on the safety of liquid nitrogen-based percutaneous cryoablation in tumors located in lung, in bones and in soft tissues. Despite using larger diameter cryoprobes than those typically reported with argon-based system, our experience shows that complications are mostly low and comparable in frequency and severity., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Institute of Radiology.)

Background: A standardized reporting system for bone and soft tissue tumor cytopathology has not yet been established. The objective of this study was to explore the potential utility of a classification modified from the Milan System for Salivary Gland Cytopathology and compared it with the upcoming World Health Organization (WHO) system for fine-needle aspiration of soft tissue lesions., Methods: The authors reviewed 285 cytology cases of bone/joint (n = 173) and soft tissue (n = 112) lesions, scoring each within diagnostic categories. The results were compared with histologic diagnoses and the risk of malignancy (ROM) for each category, and diagnostic reliability was analyzed., Results: All 285 cases were successfully classified into one of the following categories: nondiagnostic (6.3%), non-neoplastic (11.9%), atypia of uncertain significance (11.9%), benign neoplasm (5.6%), bone and soft tissue neoplasm of uncertain malignant potential (25.3%), suspicious for malignancy (1.4%), and malignant (37.5%). The ROM was 44.4% (eight of /18 cases) in nondiagnostic, 0% (zero of 34 cases) in non-neoplastic, 32.4% (11 of 34 cases) in atypia of uncertain significance, 0% (zero of 16 cases) in benign neoplasm, 16.7% (12 of 72 cases) in bone and soft tissue neoplasm of uncertain malignant potential, 75.0% (three of four cases) in suspicious for malignancy, and 100% (107 of 107 cases) in malignant categories. Using the WHO system, the proportion and ROM of the benign category (non-neoplastic and benign neoplasm) was 17.5% and 0%, respectively. Among benign and malignant lesions, the diagnostic accuracy, sensitivity, and specificity for detecting malignancy were 99.4%, 100%, and 98.0%, respectively., Conclusions: The modified Milan system as well as the WHO system may be a useful cytopathologic classification tool for both bone and soft tissue lesions., (© 2024 The Author(s). Cancer Cytopathology published by Wiley Periodicals LLC on behalf of American Cancer Society.)

With the expanding possibilities of human genome research in recent years, the number of cases of soft tissue tumors that we are able to classify into the correct subgroups and to reveal their molecular profile is increasing. Among such tumors, we can also consider neoplasms that have a specific fusion of genes, in our case namely the pleomorphic adenoma gene 1 (PLAG1) and its partner. PLAG1 gene fusions were previously associated mainly with salivary gland pleomorphic adenomas, lipoblastomas, myoepithelial tumors, uterine epitheloid, myxoid leiomyosarcomas, and, recently, with PLAG1-rearranged fibromyxoid soft tissue tumors. To our knowledge, we report the first case of a soft tissue tumor with a PLAG1 fusion gene in an adult. In our case, we detected a new H3-3B::PLAG1 fusion in a soft tissue tumor, which originally appeared as nodular fasciitis., (© 2024 The Author(s). Genes, Chromosomes and Cancer published by Wiley Periodicals LLC.)

PRRX1-fused mesenchymal neoplasm is a recently identified, rare subcutaneous soft tissue neoplasm that is characterized by fusion of PRRX1 (exon 1) with NCOA1 (exon 13) in the majority of reported cases. Although initially considered to be fibroblastic, a possibility of neural or neuroectodermal differentiation has been suggested in a subset of cases. We report a 26-year-old female with a 4.0 cm painless mass located in the subcutis of the left thigh. Microscopically, the tumor was well-circumscribed and multinodular and was composed of relatively monomorphic ovoid to spindle cells arranged in loose fascicles, trabeculae, and cords within alternating myxoid and fibrous matrix, and vascularized stroma. Mitotic figures were scarce and necrosis was not observed. By immunohistochemistry, the neoplastic cells demonstrated focal co-expression of S100 protein and SOX10 and were negative for epithelial membrane antigen, smooth muscle actin, desmin, CD34, STAT6, HMB45, Melan-A, and MUC4. The expression of Rb1 was retained. Targeted RNA-sequencing identified a novel transcript fusion of PRRX1 (exon 1)::NCOA1 (exon 15), which was further confirmed by reverse transcription polymerase chain reaction and Sanger sequencing. The tumor was narrowly excised and no tumor recurrence or metastasis was identified after 13 months of follow-up. In summary, we report a new case of PRRX1-fused mesenchymal neoplasm, expanding the molecular genetic spectrum and providing further support for possible neural or neuroectodermal differentiation of this emerging soft tissue tumor entity., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Mouse lemurs (Microcebus spp) are small Madagascan strepsirrhine primates increasingly used as an animal model in ageing research. During a period of 10 years, neoplastic disease occurred in 47 grey (Microcebus murinus) and Goodman's (Microcebus lehilahtsara) mouse lemurs from a captive colony in Germany. Approximately half of these tumours appeared histologically as soft tissue tumours (STTs) with a significantly higher proportion of STTs in Goodman's mouse lemurs (87.5%) compared with grey mouse lemurs (38.5%) (P ≤0.025). Most STTs grew subcutaneously in old or senile animals and were commonly located on the trunk, less often on the head and rarely at visceral sites. The majority of STTs were of fibrous or myofibroblastic origin, followed by undifferentiated pleomorphic sarcomas and extraskeletal chondro-osseous neoplasia. Histological grading of malignant STTs revealed all but one as grade II or III, with more than 60% being grade III. Female mouse lemurs of both species were affected significantly more often by grade II and III tumours than males (P = 0.0412). This study gives a comprehensive overview of the spectrum of mesenchymal neoplastic disease in mouse lemurs and highlights some histomorphological characteristics of spontaneous STTs in this small non-human primate species., Competing Interests: Declaration of competing interests The authors declared no conflicts of interest in relation to the research, authorship and/or publication of this article., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Soft tissue tumors of childhood are an extremely heterogeneous group of tumors that require precise diagnosis for therapy. In this article, selected tumors of uncertain origin that exhibit characteristic histological, immunophenotypical, and molecular features are addressed. Angiomatoid fibrous histiocytoma, alveolar soft part sarcoma, extrarenal rhabdoid tumor, synovial sarcoma, and desmoplastic small round cell tumor differ in their pathology, their clinical behavior, and prognosis., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Soft tissue lesions are among the most prevalent forms of tumors or tumor-like alterations within the oral cavity. They exhibit a wide spectrum of characteristics, ranging from benign, noninvasive lesions to malignant tumors, which collectively present a diagnostic challenge. A 67-year-old patient presented with an incidental finding of induration on the right cheek during dental hygiene. The intraoral examination revealed a soft, non-tender swelling measuring 20 mm in diameter. The sensitivity and percussion tests for the teeth in the fourth quadrant yielded unremarkable results. Panoramic radiography (OPG) revealed tip-ping of the premolars and an unclear apical finding in region 44. Cone-beam computed tomography (CBCT) revealed a sharply defined, lobulated hypodense lesion in the right buccal area. To clarify the diagnosis and optimize perioperative management, a 3 Tesla dental magnetic resonance imaging (MRI) scan was performed. This identified a 23×6×23 mm lipoma along the right mandibular ramus, causing detachment of the buccinator and de-pressor anguli oris muscles. A cinematic rendering reconstruction derived from the MRI data facilitated enhanced visualization for preoperative planning. The surgical excision was performed under local anesthesia, resulting in the successful removal of the neoplasm while preserving the mental nerve and submandibular gland. Histo-pathology confirmed the presence of a lobulated mature cell lipoma. The patient exhibited no complications during the removal of the sutures, with complete wound healing and no recurrence observed. This article highlights the efficacy of advanced MRI diagnostics and post-processing techniques in the management of ambiguous soft tissue neoplasms., (Copyright 2024 Adib Al-Haj Husain, Esra Salzer, Bernd Stadlinger. License: This work is licensed under a Creative Commons Attribution 4.0 International License.)

Background: Solitary fibroous tumors (SFTs) are distinctive soft tissue tumors characterized by rearrangements of NAB2-STAT6 gene, which are associated with thin-walled, branching, "staghorn"-shaped vessels. SFTs are originally classified as a type of hemangiopericytoma (HPC). Classical SFTs are composed of spindle to ovoid cells arranged haphazardly or in fascicles. Rarely, SFTs exhibit unusual morphological variants such as fat formation, giant cells, dedifferentiation, or epithelioid variant. The epithelioid cell variant, which is composed almost entirely of epithelioid cells and arranged in solid or nest patterns, is extremely rare and frequently malignant., Case Presentation: In this study, we reported three cases of epithelioid SFTs (ESFTs) located in extrathoracic sites (right lateral ventricle, right lumbar, left pelvis). All the subjects in this study were elderly, with a predominance of female patients, accounting for two out of the three cases, and only one case involved a male patient. The tumor cells were entirely composed of epithelioid cells and exhibited positive for CD34 and STAT-6 markers. Ultimately, the majority of cases (two out of three) were diagnosed as malignant SFTs., Conclusion: This study aims to enhance the awareness of ESFTs. In these cases, irrespective of the onset location, the arrangement patterns of tumor cells, such as papillary structures and the morphology of epithelial-like cells, conspicuously lack the hallmark histological characteristics of Solitary Fibrous Tumors (SFTs). Consequently, it requires differential diagnosis from a plethora of malignant neoplasms. Moreover, the elevated malignancy level of this cohort of cases poses substantial diagnostic challenges to pathologists, compounding the complexity of accurate interpretation., (© 2024. The Author(s).)