WHO classification of soft tissue tumours 2020: An update and simplified approach for radiologists

Pictorial essay on selected new, emerging, and reclassified entities in the 2020 WHO classification of soft tissue tumors

The 2020 WHO classification of soft tissue tumors includes major updates, incorporating new and emerging tumor entities, along with reclassified tumor types, supported by advances in immunohistochemistry and genetic data. This pictorial essay provides an overview of the selected new, "emerging," and reclassified soft tissue tumors, highlighting their imaging characteristics. Given the rarity of many of these entities, familiarity with their imaging features will aid in accurate diagnosis, ultimately contributing to improved patient care and management of these tumors.

Atypical spindle cell lipomatous tumor in the pelvis causing sciatic nerve compression: A case report

A 60-year-old woman with chronic lower back pain and deep gluteal pain with radicular symptoms was diagnosed with an atypical spindle cell lipomatous tumor in the pelvis compressing the sacral plexus and sciatic nerve. She underwent successful surgical excision of the tumor, resulting in significant symptom relief. This case highlights the importance of considering rare tumors in the pelvis, such as atypical spindle cell lipomatous tumors, in the differential diagnosis of radicular pain to avoid misdiagnosis.

Clinical diagnosis and treatment of abdominal inflammatory myofibroblastic tumors

OBJECTIVE

This study aims to summarize the clinicopathological characteristics, treatment methods, and prognosis of these patients. The goal is to enhance our understanding of the disease and provide insights for the standardized diagnosis and treatment of abdominal inflammatory myofibroblastic tumors(IMT).

METHODS

This retrospective cohort study included clinical data of 26 patients with abdominal IMT admitted to the First Hospital of Jilin University between January 2015 and December 2023. The clinical manifestations, pathological features, treatment methods, and prognoses were analyzed.

RESULTS

Among 26 patients, 6 had hepatic IMT, 2 splenic IMT, and 1 abdominal wall IMT, all detected incidentally as painless masses during routine exams. Six patients with mesenteric IMT reported abdominal distension, pain, nausea, vomiting, and low-grade fever. Of five patients with gastric IMT, three had gastrointestinal bleeding, one had distension and fever, and one had dysphagia. Four small intestine cases included one asymptomatic and three with obstruction symptoms. The colon and rectal cases presented with intermittent hematochezia. Surgery was performed in 24 patients, and 2 with metastases received palliative therapy. During follow-up, five patients relapsed; three received palliative therapy, and two had surgery. At last follow-up, 20 patients were disease-free, 3 were living with tumors, and 3 had died.

CONCLUSIONS

Abdominal IMTs are rare, low-grade tumors with favorable prognoses. Pathological examination is essential for diagnosis, and surgery is the primary treatment. Adjuvant therapy depends on tumor location and risk factors. Close follow-up is necessary due to the potential for recurrence and metastasis.

Stepwise Surgical Strategy for Retroperitoneal Myxofibrosarcoma with Inferior Vena Cava Reconstruction Prior to En Bloc Resection: A Case Report

Retroperitoneal sarcomas are rare and difficult to treat. Myxofibrosarcoma (MFS), a subtype of aggressive soft tissue sarcoma, primarily arises in the extremities and trunk but rarely in the retroperitoneum. When critical vascular structures are involved, prognosis worsens, necessitating a comprehensive surgical strategy to achieve complete resection and long-term control. We present a strategic plan for achieving R0 resection of a large retroperitoneal MFS. Firstly, the entire infrahepatic inferior vena cava (IVC) was replaced with a tube graft following separation of the IVC from the aorta, division of the right renal artery, and transection of both proximal and distal IVC, including its division from the renal veins. The tumor was then removed en bloc with the IVC, right kidney, and portions of the psoas and quadriceps muscles. This case emphasized the importance of detailed preoperative planning and precise intraoperative technique to ensure complete resection in complex retroperitoneal sarcomas.

Deciphering the roles of non-coding RNAs in liposarcoma development: Challenges and opportunities for translational therapeutic advances

Liposarcoma is one of the most prevalent forms of soft tissue sarcoma, and its prognosis is highly dependent on its molecular subtypes. Non-coding RNAs (ncRNAs) like microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) can bind various cellular targets to regulate carcinogenesis. By affecting the expressions and activities of their downstream targets post-transcriptionally, dysregulations of miRNAs can alter different oncogenic signalling pathways, mediating liposarcoma progression. On the contrary, lncRNAs can sponge miRNAs to spare their downstream targets from translational repression, indirectly affecting miRNA-regulated oncogenic activities. In the past 15 years, multiple fundamental and clinical research has shown that different ncRNAs play essential roles in modulating liposarcoma development. Yet, there is a lack of an effective review report that could summarize the findings from various studies. To narrow this literature gap, this review article aimed to compare the findings from different studies on the tumour-regulatory roles of ncRNAs in liposarcoma and to understand how ncRNAs control liposarcoma progression mechanistically. Additionally, the reported findings were critically reviewed to evaluate the translational potentials of various ncRNAs in clinical applications, including employing these ncRNAs as diagnostic and prognostic biomarkers or as therapeutic targets in the management of liposarcoma. Overall, over 15 ncRNAs were reported to play essential roles in modulating different cellular pathways, including apoptosis, WNT/β-catenin, TGF-β/SMAD4, EMT, interleukin, and YAP-associated pathways to influence liposarcoma development. 28 ncRNAs were reported to be upregulated in liposarcoma tissues or circulation, whereas 11 were downregulated, making them potential candidates as liposarcoma diagnostic biomarkers. Among these ncRNAs, measuring the tissues or circulating levels of miR-155 and miR-195 was reported to help detect liposarcoma, differentiate liposarcoma subtypes, and predict the survival and treatment response of liposarcoma patients. Overall, except for a few ncRNAs like miR-155 and miR-195, current evidence to support the use of discussed ncRNAs as biomarkers and therapeutic targets in managing liposarcoma is mainly based on a single-center study with relatively small sample sizes or cell-based studies. Hence, more large-scale multi-center studies should be conducted to further confirm the sensitivity, specificity, and safety of ncRNAs as biomarkers and therapeutic targets. Instead of furthering investigation to confirm the translational values of all the discussed ncRNAs, which can be time- and cost-consuming, it would be more practical to focus on a few ncRNAs, including miR-155 and miR-195, to evaluate if they are sensitive and safe to be used as liposarcoma biomarkers and therapeutic agents or targets.

Enhancing precision in sarcoma diagnosis: nCounter fusion panel implementation in a middle-income country

Background

Sarcoma diagnosis is challenging due to numerous subtypes with similar histopathological features and the high cost of fusion detection methods, particularly in middle-income countries.

Objectives

To implement a cost-effective custom-based nCounter approach previously validated for fusion analysis of suspected sarcoma in Brazil.

Design and methods

RNA isolated from 56 routine sarcomas, which were formalin-fixed and paraffin-embedded, was analyzed using a custom nCounter assay that detects 174 common sarcoma gene fusions. The results were compared to fluorescence in situ hybridization (FISH)/next-generation sequencing (NGS) and clinicopathological data.

Results

The nCounter assay was conclusive in 98.2% of cases, identifying 25 gene fusions with 82.5% accuracy, 76.6% sensitivity, and 100% specificity compared to FISH/NGS.

Conclusion

Although it does not identify all sarcoma fusions, especially for rare subtypes, the present nCounter assay is a rapid, affordable, and accurate tool for sarcoma diagnosis in resource-limited settings.

A 73-Year-Old Man With Right-Sided Chest Pain and Dyspnea

CASE PRESENTATION

A 73-year-old man presented with a 2-week history of intermittent right-sided chest pain, cough, and progressive dyspnea on exertion. He reported subjective weight loss and anorexia with early satiety over the preceding months. He denied any fevers, night sweats, or sick contacts. On further questioning, he had also noted some progressive abdominal distension, though denied any change in bowel habits, nausea, or vomiting. He had a history of hypertension and diabetes. He was a person who does not smoke and had worked in the construction industry for > 50 years prior. His daughter had passed away due to lung cancer.

Sclerosing well-differentiated liposarcoma: two diagnostically challenging mimicker cases and a literature review

Liposarcoma is a malignant soft tissue tumor with several subtypes, the most common of which is well-differentiated liposarcoma (WDL) or atypical lipomatous tumor (ALT). WDL/ALTs are further divided into three histological subtypes, including lipoma-like, sclerosing, and inflammatory. While the majority of these tumors are predominantly fatty, the sclerosing variant demonstrates diverse histologic and radiographic characteristics, including variable amounts of fibrosis and fat. Because of this histological variability and relative rarity, the sclerosing WDL/ALT can present diagnostic dilemmas. We present two cases of sclerosing WDL/ALT, both of which demonstrated high degrees of fibrosis and a paucity of fat, mimicking desmoid fibromatosis and other fibrotic soft tissue tumors. Thus, it is important for radiologists to be aware of the subtypes of liposarcoma and their unique characteristics, and to consider sclerosing WDL/ALT in cases of fibrotic soft tissue tumors.

Laparoscopic Abdominoperineal Resection of Undifferentiated Spindle Cell Sarcomas of the Rectum with Lymph Node Metastases: A Rare Case Report

INTRODUCTION

Undifferentiated sarcomas of the gastrointestinal tract are rare and have poor prognoses, especially those with lymph node metastases. There is no consensus on the treatment plan. While there are reports on undifferentiated pleomorphic sarcomas of the rectum, no reports on undifferentiated rectal spindle sarcomas with lymph node metastases have been presented previously.

CASE PRESENTATION

We report a case of a 97-year-old woman referred to our hospital with anal pain. Imaging findings indicated multiple tumors in the rectum below the peritoneal reflection protruding from the anus and two enlarged pararectal lymph nodes. Laparoscopic abdominoperineal resection of the rectal sarcomas with lymph node metastasis was performed to alleviate the pain with uneventful postoperative courses. The immunostaining did not reveal a trend of tumor cell differentiation. The tumor was diagnosed as undifferentiated spindle cell sarcoma based on histopathological findings. Because of advanced age, the patient is followed up on an outpatient basis without additional postoperative treatment.

CONCLUSION

The prognosis of undifferentiated sarcomas is poor. While radical resection is the primary treatment, the efficacy of preoperative radiation therapy, cytotoxic chemotherapy, and immune checkpoint inhibitors has been investigated recently. Accumulating cases of this disease is important to determine treatment plans, and this report is valuable in this regard.

NAB2-STAT6 drives an EGR1-dependent neuroendocrine program in Solitary Fibrous Tumors

The pathogenesis of many rare tumor types is poorly understood, preventing the design of effective treatments. Solitary fibrous tumors (SFTs) are neoplasms of mesenchymal origin that affect 1/1,000,000 individuals every year and are clinically assimilated to soft tissue sarcomas. SFTs can arise throughout the body and are usually managed surgically. However, 30-40% of SFTs will relapse local-regionally or metastasize. There are no systemic therapies with durable activity for malignant SFTs to date. The molecular hallmark of SFTs is a gene fusion between the NAB2 and STAT6 loci on chromosome 12, resulting in a chimeric protein of poorly characterized function called NAB2-STAT6. We use primary samples and an inducible cell model to discover that NAB2-STAT6 operates as a transcriptional coactivator for a specific set of enhancers and promoters that are normally targeted by the EGR1 transcription factor. In physiological conditions, NAB2 is primarily localized to the cytoplasm and only a small nuclear fraction is available to operate as a co-activator of EGR1 targets. NAB2-STAT6 redirects NAB1, NAB2, and additional EGR1 to the nucleus and bolster the expression of neuronal EGR1 targets. The STAT6 moiety of the fusion protein is a major driver of its nuclear localization and further contributes to NAB2's co-activating abilities. In primary tumors, NAB2-STAT6 activates a neuroendocrine gene signature that sets it apart from most sarcomas. These discoveries provide new insight into the pathogenesis of SFTs and reveal new targets with therapeutic potential.

New Abdominal Mass After Surgery for Gastrointestinal Stromal Tumor: Desmoid-Type Fibromatosis Difficult to Distinguish from Mesenchymal Tumor - A Case Report

A new lump in patients with a history of gastrointestinal stromal tumor (GIST) may indicate resistance to medication and recurrence. It is important to monitor for recurrence or metastasis after surgery for GIST, especially in cases of high-risk GIST, as it determines the subsequent treatment. However, it is difficult to differentiate between GIST and DF by imaging. Tissue biopsy and final diagnosis through pathological analysis are usually required. Here, we report 2 cases of primary diagnosis with high-risk GIST and suspected tumor recurrence during Imatinib treatment. The mass was not located where the previous GIST lesion had been. After the complete excision of the mass through laparoscopic surgery, the pathological findings revealed that it was not a recurrence of GIST, but a desmoid-type fibromatosis.

Primary mesenchymal tumors of the prostate:18F FDG PET/CT findings

BACKGROUND

Primary mesenchymal tumors of the prostate are very rare, and there is no systematic report on fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT). The aim of this research was to characterize mesenchymal tumors of the prostate on 18F-FDG PET/CT.

RESULTS

We included 13 patients with pathologically confirmed mesenchymal neoplasms of the prostate. The location, size, maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), total glycolysis of the lesion (TLG), pathologic findings, and available imaging study of the tumors were reviewed. Of the 13 patients (median age, 38 years; ranged from 13 to 74 years), the mean size of the tumors was 8.8 cm in diameter ranged from 5 to 16.1 cm. SUVmax ranged from 3.1 to 17.6 (mean 9.5), MTV ranged from 4.9 to 398 cm3 (mean 109 cm3) and TLG ranged from 21.3 to 1216 g (mean 96 g). The seminal vesicles, rectum, and bladder are the most commonly affected sites of invasion, while metastasis typically occurs in the bones, lungs, and lymph nodes.

CONCLUSIONS

Mesenchymal tumors of the prostate revealed large sizes and high SUVmax, MTV and TLG levels on 18F-FDG PET/CT. 18F-FDG PET/CT may be useful for accurate diagnosis, staging, and restaging, which plays an important role in the management of subsequent plans.

Sarcoma or haematoma? If only it was that simple! Part 2

Introduction

Imaging appearances and clinical presentation of soft tissue sarcoma and soft tissue haematomas are similar. It is imperative that sarcoma is differentiated from benign soft tissue lesions due to the poor outcomes and high morbidity associated with sarcoma.

Topic Description

Part 2 of this pictorial review summarises the key ultrasound appearances of soft tissue sarcoma and soft tissue haematomas and some differential diagnoses.

Discussion

Ultrasound is the first line test in the investigation of soft tissue masses. With the overlapping ultrasound appearances of soft tissue sarcoma and soft tissue haematomas, it is essential that practitioners are aware of key ultrasound appearances and understand when to escalate cases for further investigation.

Conclusion

Sound knowledge of the clinical and sonographic features of soft tissue haematomas and soft tissue sarcoma as well as recognising potential differential diagnoses is fundamental to ensuring an accurate diagnosis, timely management and improved patient outcomes.

Anlotinib treatment for rapidly progressing pediatric embryonal rhabdomyosarcoma in the maxillary gingiva: a case report

BACKGROUND

Embryonal rhabdomyosarcoma (ERMS) is a highly aggressive form of soft-tissue sarcoma that predominantly affects children. Due to limited benefits and resistance to therapy, there is an unmet need to explore alternative therapeutic strategies.

CASE PRESENTATION

In this report, we present a rare case of pediatric ERMS located on the right side of the maxillary gingiva. A composite reference guide integrating clinical, radiographic, and histopathologic findings was used for a definitive diagnosis. Targeted next-generation sequencing of tumor biopsy was performed to identify genetic alterations. A 12-year-old female was admitted to the Pediatric Intensive Care Unit (PICU) and underwent a tracheotomy to relieve asphyxiation caused by a 5.5 cm diameter mass compressing the tongue root and pharyngeal cavity. Hematoxylin and eosin staining revealed a hybrid morphology characterized by clusters of round and spindle cells. Further immunohistochemistry assays indicated positive immunoreactivity for desmin, myogenin, and MyoD1. Various genetic alterations were identified, including mutations in GNAS, HRAS, LRP1B, amplification of MDM2 and IGF1R, and two novel IGF1R fusions. Negative PAX-FOXO1 fusion status supported the clinical diagnosis of ERMS. Initial treatment involved standard chemotherapy; however, the tumor persisted in its growth, reaching a maximum volume of 12 cm × 6 cm × 4 cm by the completion of treatment. Subsequent oral administration of anlotinib yielded a significant antitumor response, characterized by substantial tumor necrosis and size reduction. Following the ligation of the tumor pedicle and its removal, the patient developed a stabilized condition and was successfully discharged from PICU.

CONCLUSIONS

Our study highlights the importance of accurate diagnosis established on multifaceted assessment for the effective treatment of ERMS. We present compelling evidence supporting the clinical use of anlotinib as a promising treatment strategy for pediatric ERMS patients, especially for those resistant to conventional chemotherapy.

Sarcoma or haematoma? If only it was that simple! Part 1

Introduction

Imaging appearances and clinical presentation of soft tissue sarcoma and soft tissue haematomas are similar. It is imperative that sarcoma is differentiated from benign soft tissue lesions due to the poor outcomes and high morbidity associated with sarcoma.

Topic description

Part 1 of this pictorial review will summarise the paucity of guidance in management of suspected haematomas, the clinical features and ultrasound techniques used in the assessment of soft tissue masses.

Discussion

Ultrasound is the first-line test in the investigation of soft tissue masses. With the overlapping ultrasound appearances of soft tissue sarcoma and soft tissue haematoma, thorough and methodical clinical examination and scanning technique is fundamental so that practitioners understand when to escalate cases for further investigation.

Conclusion

The clinical assessment and clinical history taking into consideration the intensity of trauma and ecchymosis must correlate with the ultrasound appearances. This will facilitate an accurate diagnosis, timely management and improved patient outcomes.

Retrospective analysis of radiological investigation of surgically excised head and neck lipomas

PURPOSE

Differentiating benign lipomas from malignant causes is challenging and preoperative investigative guidelines are not well-defined. The purpose of this study was to retrospectively identify cases of head and neck lipomas that were surgically resected over a 5-year period and to identify the radiological modality chosen and features discussed in the final report. Multidisciplinary outcomes and pathology reports were examined with a view to identifying high risk features of a lipoma to aid in future risk stratification.

METHODS

Retrospective chart review of pathology characteristics, radiological features (modality, size, calcifications, septations, globular/nodular foci), multidisciplinary discussion and history of presenting complaint was performed.

RESULTS

Two liposarcomas and 138 lipomas were identified. Twenty-two percent of all lipomas received radiological investigation. Twenty-two percent of imaging referrals were possibly inappropriate. Furthermore, radiological features suggestive of malignancy were not present in the final radiology report, X2 = 28.8, p < 0.0001.

CONCLUSION

As expected, the incidence of liposarcoma is low. There is limited awareness of radiology referral guidelines superimposed with a tendency to over-investigate lipomas. Furthermore, radiological features suggestive of malignancy were inconsistently reported on and not documented in multidisciplinary discussions. Therefore, we propose a multidisciplinary checklist for referring physicians and radiologists to aid in diagnostic work-up.

[Innovations in the classification of soft tissue tumors]

Soft tissue tumors are a very heterogeneous group of tumors. Their classification is regularly updated by the World Health Organization (WHO), most recently in 2020. The current classification of soft tissue tumors emphasizes molecular biological tumor characteristics, which enable tumor-specific treatment. In addition to Ewing's sarcoma, which occurs as bone as well as extra-skeletal soft tissue tumors as a small round cell sarcoma, three other subtypes of undifferentiated, small and round cell sarcomas have been introduced. Some names of the new sarcomas can be derived from the gene mutations. The groups of adipocytic and (myo)fibroblastic tumors have been extended by three further entities. There were further additions to vascular soft tissue tumors, smooth muscle cell tumors, peripheral nerve sheath tumors and tumors of uncertain differentiation. A distinction is made between benign, intermediate locally aggressive, intermediate rarely metastatic and malignant soft tissue tumors.

Epstein-Barr Virus-Associated Smooth-Muscle Tumor of the Brain

Epstein-Barr virus, a herpesvirus, has been associated with a variety of cancers, including Burkitt, Hodgkin, and non-Hodgkin lymphomas; posttransplant lymphoproliferative disorders; gastric carcinoma; and nasopharyngeal carcinoma, in both immunocompetent and immunocompromised individuals. Previous studies have established a connection between Epstein-Barr virus and the development of smooth-muscle tumors. Smooth-muscle tumors of the brain are very rare and are often misdiagnosed as meningiomas on imaging. To our knowledge, advanced imaging findings such as MR perfusion of smooth-muscle tumors of the brain have never been reported. We describe the radiologic and pathologic features of the Epstein-Barr virus-associated smooth-muscle tumors of the brain in a person with newly diagnosed advanced HIV.

Peripheral Vascular Compression in a Patient With Diffuse Tenosynovial Giant Cell Tumor of the Knee: A Case Report Focusing on the Role of the Ultrasound

Tenosynovial giant cell tumors (TGCTs) are benign histo-fibrocystic tumors originating from the synovium of joints, bursae, or tendon sheaths. They are categorized into localized and diffuse types, each with distinct clinical presentations and management approaches. The diffuse form, which is rare, generally affects a single joint and is characterized by joint swelling, pain, functional limitation, and often hemarthrosis. While MRI is commonly used for diagnosis, we present a case highlighting ultrasound's significance in diagnosing and managing TGCTs, particularly for identifying vascular complications. A 59-year-old female with a 10-year history of recurrent swelling, pain, and functional limitation of the right knee was evaluated for persistent symptoms and unilateral right peripheral edema. Ultrasound revealed multiple hypoechoic, vascularized masses with both homogeneous and heterogeneous echostructures and a significant suprapatellar effusion. An ultrasound-guided biopsy confirmed the diagnosis of a recurrent diffuse TGCT complicated by vascular compression of the popliteal vein. The patient underwent mass resections, total synovectomy, and radiotherapy to reduce the risk of recurrence.  Ultrasound is cost-effective and highly beneficial for the diagnosis, treatment planning, and monitoring of diffuse TGCTs. Total synovectomy combined with radiotherapy or intra-articular yttrium-90 injection is the preferred treatment to prevent recurrence and complications.

Molecular Imaging in Soft-tissue Sarcoma: Evolving Role of FDG PET

Soft tissue sarcomas are a rare and heterogenous group of tumors that account for 2% of all cancer-related deaths. Molecular imaging with FDG PET can offer valuable metabolic information to help inform clinical management of soft tissue sarcomas that is unique and complementary to conventional diagnostic imaging techniques. FDG PET imaging often correlates with tumor grade, can help guide biopsy, and frequently detects additional sites of disease compared to conventional imaging in patients being considered for definitive or salvage therapy. Traditional size-based evaluation of treatment response is often inadequate in soft tissue sarcoma and changes in metabolic activity can add significant value to interim and end of treatment imaging for high-grade sarcomas. FDG PET can be used for detection of recurrence or malignant transformation and thus play a vital role in surveillance. This article reviews the evolving role of FDG PET in initial diagnosis, staging, treatment response assessment, and restaging. Further studies on the use of FDG PET in soft sarcoma are needed, particularly for rare histopathologic subtypes.

CT and MR imaging findings of head and neck chondrosarcoma

OBJECTIVES

This study investigated the imaging features of head and neck chondrosarcoma (HNCS) according to its origin and pathologic subtype.

METHODS

Patients who were pathologically diagnosed with HNCS between January 2000 and April 2022 were retrospectively reviewed. Lesions were classified based on their origin and pathologic subtype. The size and margin were evaluated on the image. Internal calcification and the effects on adjacent bone were assessed using computed tomography (CT) images, while signal intensity and contrast enhancement patterns were analyzed using magnetic resonance (MR) imaging.

RESULTS

Thirteen HNCSs were included in this study: 8 bone tumors (61.5%) and 5 soft tissue tumors (38.5%). The bone tumors were pathologically diagnosed as conventional (n = 5) and mesenchymal type (n = 3). Soft tissue tumors were defined as myxoid type. The main symptoms were swelling (90.9%) and pain (72.7%). The lesions measured 4.5 cm on average. The margins showed benign and well-defined except for the mesenchymal type. On CT, most bone tumors (75%) showed internal calcification with remodeling or destruction of the adjacent bone. No soft tissue tumors, except one case, showed internal calcification or destruction of the adjacent bone. MR imaging features were non-specific (T2 high signal intensity and contrast enhancement).

CONCLUSIONS

HCNS showed various imaging findings according to their origin and pathologic subtype. HNCS should be differentiated if a bone tumor shows internal calcification and affects the adjacent bone. When diagnosing slow-growing soft tissue tumors, even if low possibility, HNCS should be considered.

Positron Emission Tomography/Computed Tomography Transformation of Oncology: Musculoskeletal Cancers

The past 25 years have seen significant growth in the role of positron emission tomography/computed tomography (PET/CT) in musculoskeletal oncology. Substantiative advances in technical capability and image quality have been paralleled by increasingly widespread clinical adoption and implementation. It is now recognized that PET/CT is useful in diagnosis, staging, prognostication, response assessment, and surveillance of bone and soft tissue sarcomas, often providing critical information in addition to conventional imaging assessment. As individualized, precision medicine continues to evolve for patients with sarcoma, PET/CT is uniquely positioned to offer additional insight into the biology and management of these tumors.

Case report: Solitary mass of the sciatic nerve confirmed as a primary extranodal manifestation of diffuse large B-cell lymphoma in a geriatric patient

Background

Neoplastic lesions affecting peripheral nerves are rare in the general population and, most often, are benign peripheral nerve sheath tumors. However, a minority of lesions represent high-grade malignancies associated with a poor prognosis, such as malignant peripheral nerve sheath tumors (MPNSTs). Very rarely, these tumors represent peripheral non-nerve sheath tumors (PNNSTs), such as hematological neoplasms that impair nerve function. These can be hard to distinguish from MPNSTs and other lesions arising from the nerve itself. In the present case report, we describe a rare case of direct infiltration of nerves by tumor cells of a hematological neoplasm.

Methods

We report the case of a 90-year-old woman with acute onset of right-sided foot palsy, sensory loss, and pain, caused by an extensive solitary mass of the sciatic nerve in the thigh. We present and discuss the clinical presentation, multimodal diagnostic procedures, and treatment.

Results

MRI of the right thigh and the caudal pelvis revealed a contrast-enhancing lesion infiltrating the sciatic nerve. Additionally performed staging imaging was non-revealing. After multidisciplinary discussion in the neuro-oncology tumor board, a MPNST was suspected and the patient underwent radical tumor resection. However, final histopathology revealed a diffuse large B-cell lymphoma (DLBCL). The patient received adjuvant palliative local radiotherapy which led to acceptable symptom control.

Conclusion

Rare PNNSTs, including extranodal manifestations of DLBCL can have similar clinical and radiological diagnostical features as PNSTs. Comprehensive diagnostic workup of contrast-enhancing lesions affecting peripheral nerves including MRI and metabolic imaging are recommended. Discussion in interdisciplinary tumor boards facilitates finding individual treatment approaches.

Arthroscopic Excision of a Localized Tenosynovial Giant Cell Tumor of the Knee: A Case Report

BACKGROUND AND AIM

A tenosynovial giant cell tumor (TGCT) is a proliferative lesion of the synovial membrane of the joints, tendon sheaths and/or bursae. There are two described subtypes, including the localized and diffuse forms. A TGCT can also be intraarticular or extraarticular. An intraarticular localized tenosynovial giant cell tumor (L-TGCT) of the knee is characterized by nodular hyperplasic synovial tissue that can remain asymptomatic for a long time, but as the mass grows, it may cause mechanical symptoms that may require surgical treatment. The aim of our study is to present a rare case of an L-TGCT of the knee joint treated with an arthroscopic excision.

CASE REPORT

We describe the case of a 17-year-old female with pain, swelling and knee locking in the absence of trauma. The magnetic resonance imaging (MRI) displayed a well-circumscribed small mass in the anterior medial compartment, adherent to the infrapatellar fat pad. The lesion presented the typical MRI characteristics of an intraarticular localized TGCT. The patient was treated with an arthroscopic mass removal and partial synovectomy. The gross pathology showed an ovoid nodule that was covered by a fibrous capsule; a histopathology examination confirmed the diagnosis. The patient was able to return to normal daily activities one month after surgery; at the three-year follow-up, she was free of symptoms with no evidence of disease on the MRI.

CONCLUSION

In patients with a small-dimension L-TGCT in the anterior compartment of the knee that presents an MRI pattern and causes mechanical symptoms, an arthroscopic en-bloc excision can be performed that results in good outcomes and a rapid return to preinjury levels.

Emerging innovations and advancements in the treatment of extremity and truncal soft tissue sarcomas

In this special edition update on soft tissue sarcomas (STS), we cover classifications, emerging technologies, prognostic tools, radiation schemas, and treatment disparities in extremity and truncal STS. We discuss the importance of enhancing local control and reducing complications, including the role of innovative imaging, surgical guidance, and hypofractionated radiation. We review advancements in systemic and immunotherapeutic treatments and introduce disparities seen in this vulnerable population that must be considered to improve overall patient care.

Establishment and validation of nomogram models for overall survival and cancer-specific survival in spindle cell sarcoma patients

Spindle cell sarcoma (SCS) is rare in clinical practice. The objective of this study was to establish nomograms to predict the OS and CSS prognosis of patients with SCS based on the Surveillance, Epidemiology, and End Results (SEER) database. The data of patients with SCS between 2004 and 2020 were extracted from the SEER database and randomly allocated to a training cohort and a validation cohort. Univariate and multivariate Cox regression analyses were used to screen for independent risk factors for both overall survival (OS) and cancer-specific survival (CSS). Nomograms for OS and CSS were established for patients with SCS based on the results of multivariate Cox analysis. Then, we validated the nomograms by the concordance index (C-index), receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA). Finally, Kaplan‒Meier curves and log-rank tests were applied to compare patients with SCS at three different levels and in different treatment groups. A total of 1369 patients with SCS were included and randomly allocated to a training cohort (n = 1008, 70%) and a validation cohort (n = 430, 30%). Age, stage, grade, tumour location, surgery, radiation and diagnosis year were found to be independent prognostic factors for OS by Cox regression analysis, while age, stage, grade, tumour location and surgery were found to be independent prognostic factors for CSS. The nomogram models were established based on the results of multivariate Cox analysis for both OS and CSS. The C-indices of the OS model were 0.76 and 0.77 in the training and validation groups, respectively, while they were 0.76 and 0.78 for CSS, respectively. For OS, the 3- and 5-year AUCs were 0.801 and 0.798, respectively, in the training cohort and 0.827 and 0.799, respectively, in the validation cohort; for CSS, they were 0.809 and 0.786, respectively, in the training cohort and 0.831 and 0.801, respectively, in the validation cohort. Calibration curves revealed high consistency in both OS and CSS between the observed survival and the predicted survival. In addition, DCA was used to analyse the clinical practicality of the OS and CSS nomogram models and revealed that they had good net benefits. Surgery remains the main treatment method for SCS patients. The two nomograms we established are expected to accurately predict the personalized prognosis of SCS patients and may be useful for clinical decision-making.

Pediatric presacral tumors with intraspinal extension: a rare entity with diagnostic challenges

The presacral space is a potential space located between the rectum and the lumbosacral spine. It contains various primitive germ cell types that serve as the origin for a range of tumors. Imaging is crucial in characterizing, assessing the extent of and evaluating the treatment response to these tumors. We report a series of six cases of pediatric presacral tumors with intraspinal extension, including an immature sacrococcygeal teratoma (Altman type II), a malignant sacrococcygeal teratoma (Altman type IV), a neuroblastoma, a rhabdomyosarcoma, a clear cell sarcoma and an Ewing's sarcoma of the ilium. These tumors can be broadly categorized as tumors of germ cell, neuroblastic, mesenchymal and osteogenic origin. Despite overlapping imaging features, a review of the existing literature and careful retrospective observation revealed several distinctive features that aid in the optimal characterization of tumors. These include the tumor's epicenter, the pattern and degree of bone involvement, the status of sacral foramina and neural elements, and internal tumor characteristics such as the presence of fat, calcification, hemorrhage and necrosis.

Diagnosis of inflammatory myofibroblastic tumor in a pediatric patient initially suspected of tuberculosis

BACKGROUND

Symptoms of inflammatory myofibroblastic tumor (IMT) are atypical, and histopathological misdiagnosis of IMT is still inevitable. Here we present a pediatric case that an eight-year-old boy with recurrent fever for fifteen months, received anti-tuberculosis therapy for five months and was ultimately confirmed to be IMT.

CASE PRESENTATION

An eight-year-old boy experienced a recurrent fever for fifteen months, accompanied by cough, vomiting, meteorism, night sweating, and emaciation. Thoracoabdominal computer tomography revealed multiple enlarged lymph nodes in the thorax, abdomen, and axilla, as well as minimal bilateral pleural effusion. Histopathological examinations of the intestines and greater omentum implied fibrous tissue hyperplasia along with eosinophil and lymphocyte infiltration. The patient was initially misdiagnosed with tuberculosis, and symptoms were relieved partially following anti-tuberculosis treatment. However, after four months, the symptoms aggravated again and a subsequent histopathological analysis of a second sample from the greater omentum revealed the presence of IMT. Eventually, after surgical resection of the lesions and chemotherapy, the clinical symptoms in the child gradually alleviated.

CONCLUSIONS

The clinical course of IMT is variable, and pediatricians should pay attention to differentiating IMT from tuberculosis.

Synovial sarcoma in the prevertebral space can mimic malignant neurogenic neoplasm: Case report and literature review

Synovial sarcoma, a rare malignant neoplasm with a poor prognosis, accounts for approximately 5%-10% of all primary soft-tissue malignancies worldwide. Typically affecting adolescents and young adults, it primarily manifests near the joints of the lower extremities. This study aimed to demonstrate that this tumor can also affect the prevertebral space. A 32-year-old male patient presented at our outpatient clinic with a 2-month history of upper limb numbness and a 1-month complaint of palpable neck mass. Imaging studies revealed a bulky, lobulated, and heterogeneous mass exhibiting heterogeneous enhancement. Furthermore, the mass caused expansion of the neuroforamen in the neck, initially suggesting a diagnosis of malignant schwannoma. However, a histopathologic examination suggested synovial sarcoma. The article provided a comprehensive review of the clinical, pathological, and radiological features of this condition. Additionally, it explored current treatment options and prognoses by referencing relevant literature.

MRI Prediction Model for Tenosynovial Giant Cell Tumor with Risk of Diffuse-type

RATIONALE AND OBJECTIVES

To propose a magnetic resonance imaging (MRI) prediction model for diffuse-type tenosynovial giant cell tumors (D-TSGCTs).

MATERIALS AND METHODS

Anatomic locations were classified and then nodularity, margin, peripheral and internal hypointensity, and bone and cartilage involvement were evaluated on MRI. Student's t-test, chi-square test, diagnostic performance, logistic regression analysis, and decision tree were performed.

RESULTS

Nineteen intra-articular (11 localized; eight diffuse) and 55 extra-articular (44 localized; 11 diffuse) TSGCTs were included. Extra-articular D-TSGCTs showed significantly more frequent multinodular (72.7% vs. 25.0%, p = 0.009), and infiltrative lesions (90.9% vs. 34.1%, p = 0.002), without peripheral hypointensity (90.9% vs. 18.2%, p < 0.001), and contained granular internal hypointensity (72.7% vs. 31.8%; p = 0.003) with more frequent bone (81.8% vs. 27.3%; p = 0.003) and cartilage (50.0% vs. 0.0%; p = 0.038) involvement than localized-type. Intra-articular D-TSGCT also showed significance in all MRI features (100.0% vs. 9.1%, p = 0.001; 100.0% vs. 27.3%, p = 0.007; 100.0% vs. 36.4%, p = 0.018; 100.0% vs. 27.3%, p = 0.007; 50.0% vs. 0.0%, p = 0.038), except bone involvement (37.5% vs. 9.1%, p = 0.352) than localized-type. Cartilage involvement revealed the highest specificity (88.6-100.0%), regardless of location. Nodularity (100.0%; odds-ratio [OR]: 70.000) and peripheral hypointensity (90.9%; OR: 62.250) demonstrated the highest sensitivities ORs for D-TSGCT in intra-articular and extra-articular cases, respectively. MRI models for D-TSGCG beginning with the cartilage involvement in both anatomic locations and next on nodularity and peripheral hypointensity in intra-articular and extra-articular locations, respectively, exhibited sensitivity and specificity of 100% and 90.9% for intra-articular and 100% and 77.2% for extra-articular TSGCTs, respectively.

CONCLUSION

MRI can suggest the risk of D-TSGCT by combining imaging features with anatomic locations.

Primary renal malignant epithelioid angiomyolipoma with distant metastasis: a case report and literature review

Epithelioid angiomyolipoma (EAML) is a rare type of mesenchymal angiomyolipoma with potential malignancy in the kidney that can cause lymph node metastases, local recurrence, and distant metastases. Herein, we describe a case of EAML in the right kidney of a 51-year-old man who was admitted to the hospital with a right abdominal mass. Computed tomography revealed a heterogeneously enhanced mass with blurred margins, which was considered a malignant tumor. A radical nephrectomy was then performed. Two years later, the patient developed liver metastases from EAML and was administered sintilimab combined with bevacizumab. The patient survived after 6 months of follow-up. Histologically, the tumors showed clear boundaries and no obvious capsules. The tumor tissue mainly consisted of epithelioid tumor cells, thick-walled blood vessels, and a small amount of adipose tissue. Tumor cells with lipid vacuoles and acinar areas were large, round, polygonal, eosinophilic, or transparent in the cytoplasm. The enlarged and hyperchromatic nuclei were accompanied by distinct nucleoli and pathological mitosis. These histopathological findings resembled those of renal cell carcinoma, and immunohistochemical analysis was performed. The tumor cells were diffusely positive for HMB45, Melan-A, CK20, vimentin antibodies, and TFE3, suggesting that the tumor originated from perivascular epithelioid cells, excluding renal cell carcinoma. The Ki-67 index was 10%. These histopathological features were observed in liver mass puncture tissues. We also summarized 46 cases of EAML with distant metastasis and explored the clinicopathological features of EAML to improve the treatment of the disease. EAML is often ignored in the clinical setting, leading to metastasis and recurrence. Therefore, EAMLs require long-term follow-up, and timely detection of recurrent disease can improve the prognosis.

Understanding a mass in the paraspinal region: an anatomical approach

The paraspinal region encompasses all tissues around the spine. The regional anatomy is complex and includes the paraspinal muscles, spinal nerves, sympathetic chains, Batson's venous plexus and a rich arterial network. A wide variety of pathologies can occur in the paraspinal region, originating either from paraspinal soft tissues or the vertebral column. The most common paraspinal benign neoplasms include lipomas, fibroblastic tumours and benign peripheral nerve sheath tumours. Tumour-like masses such as haematomas, extramedullary haematopoiesis or abscesses should be considered in patients with suggestive medical histories. Malignant neoplasms are less frequent than benign processes and include liposarcomas and undifferentiated sarcomas. Secondary and primary spinal tumours may present as midline expansile soft tissue masses invading the adjacent paraspinal region. Knowledge of the anatomy of the paraspinal region is of major importance since it allows understanding of the complex locoregional tumour spread that can occur via many adipose corridors, haematogenous pathways and direct contact. Paraspinal tumours can extend into other anatomical regions, such as the retroperitoneum, pleura, posterior mediastinum, intercostal space or extradural neural axis compartment. Imaging plays a crucial role in formulating a hypothesis regarding the aetiology of the mass and tumour staging, which informs preoperative planning. Understanding the complex relationship between the different elements and the imaging features of common paraspinal masses is fundamental to achieving a correct diagnosis and adequate patient management. This review gives an overview of the anatomy of the paraspinal region and describes imaging features of the main tumours and tumour-like lesions that occur in the region.

Prediction of local recurrence in tenosynovial giant cell tumor of the knee: Based on preoperative MRI evaluation into disease subtypes and severity

OBJECTIVE

Tenosynovial giant cell tumors (TSGCTs) of the knee differ in their clinical outcome according to disease subtypes and severity. The aim of this study was to determine the predictive MRI features related to local recurrence in TSGCT of the knee regarding disease subtypes and severity.

METHODS

This retrospective study included 20 patients with pathology-proven TSGCT of the knee who underwent preoperative MRI and surgery from Jan. 2007 to Jan. 2022. The anatomical point of the lesion was determined with a knee mapping. And then MRI features related to disease subtype including nodularity (single vs. multinodular); margin (circumscribed vs. infiltrative); peripheral hypointenseity (present vs. absent); internal hypointensity reflecting hemosiderin deposition (speckled vs. granular) were assessed. Third, MRI features related to disease severity including involvement of bone, cartilage, and tendon were evaluated. MRI features for predicting local recurrence of TSGCT were tested using chi-square test and logistic regression analysis.

RESULTS

Ten patients with diffuse-type TSGCT (D-TSGCT) and 10 patients with localized-type TSGCT (L-TSGCT) were included. There were six cases of local recurrence and all of them were D-TSGCT and none for L-TSGCT with statistical difference (P = 0.015). D-TSGCT that was direct risk factor for local recurrence showed more multinodular (80.0% vs. 10.0%; P = 0.007), infiltrative margin (90.0% vs. 10.0%; P = 0.002), and absent peripheral hypointensity (100.0% vs. 20.0%; P = 0.001) than L-TSGCT. Multivariate analysis showed infiltrative margin (odds ratio [OR], 81.0; P = 0.003) was independent MRI factor for D-TSGCT. Disease severity for risk of local recurrence included cartilage (66.7% vs. 7.1%; P = 0.024) and tendon (100.0% vs. 28.6%; P = 0.015) involvement compared to no local recurrence. Multivariate analysis showed tendon involvement (OR, 12.5; P = 0.042) was predictive MRI parameter for local recurrence. By combining tumor margin and tendon involvement, local recurrence was predicted sensitively on preoperative MRI (sensitivity, 100%; specificity, 50%; accuracy, 65%).

CONCLUSION

D-TSGCTs was associated with local recurrence and showed multinodularity infiltrative margin, and absent peripheral hypointensity. Disease severity including cartilage and tendon involvement was associated with local recurrence. Preoperative MRI evaluation by combining disease subtypes and severity can predict local recurrence sensitively.

A multiparametric clinic-ultrasomics nomogram for predicting extremity soft-tissue tumor malignancy: a combined retrospective and prospective bicentric study

OBJECTIVE

We aimed at building and testing a multiparametric clinic-ultrasomics nomogram for prediction of malignant extremity soft-tissue tumors (ESTTs).

MATERIALS AND METHODS

This combined retrospective and prospective bicentric study assessed the performance of the multiparametric clinic-ultrasomics nomogram to predict the malignancy of ESTTs, when compared with a conventional clinic-radiologic nomogram. A dataset of grayscale ultrasound (US), color Doppler flow imaging (CDFI), and elastography images for 209 ESTTs were retrospectively enrolled from one hospital, and divided into the training and validation cohorts. A multiparametric ultrasomics signature was built based on multimodal ultrasomic features extracted from the grayscale US, CDFI, and elastography images of ESTTs in the training cohort. Another conventional radiologic score was built based on multimodal US features as interpreted by two experienced radiologists. Two nomograms that integrated clinical risk factors and the multiparameter ultrasomics signature or conventional radiologic score were respectively developed. Performance of the two nomograms was validated in the retrospective validation cohort, and tested in a prospective dataset of 51 ESTTs from the second hospital.

RESULTS

The multiparametric ultrasomics signature was built based on seven grayscale ultrasomic features, three CDFI ultrasomic features, and one elastography ultrasomic feature. The conventional radiologic score was built based on five multimodal US characteristics. Predictive performance of the multiparametric clinic-ultrasomics nomogram was superior to that of the conventional clinic-radiologic nomogram in the training (area under the receiver operating characteristic curve [AUC] 0.970 vs. 0.890, p = 0.006), validation (AUC: 0.946 vs. 0.828, p = 0.047) and test (AUC: 0.934 vs. 0.842, p = 0.040) cohorts, respectively. Decision curve analysis of combined training, validation and test cohorts revealed that the multiparametric clinic-ultrasomics nomogram had a higher overall net benefit than the conventional clinic-radiologic model.

CONCLUSION

The multiparametric clinic-ultrasomics nomogram can accurately predict the malignancy of ESTTs.

Imaging Recommendations for Diagnosis, Staging, and Management of Soft Tissue Sarcomas

Soft tissue lesions are a wide range of tumors of mesenchymal cell origin, occurring anywhere in the body with a vast number of histological subtypes both benign and malignant. These are common in clinical practice and vast majority are benign. This article focuses on soft tissue sarcoma of the trunk and extremities and discusses their imaging guidelines.

Musculoskeletal Soft-tissue Masses

Evaluation of soft-tissue masses has become a common clinical practice indication for imaging with both ultrasound and MR imaging. We illustrate the ultrasonography and MR imaging appearances of soft-tissue masses based on the various categories, updates, and reclassifications of the 2020 World Health Organization classification.

Desmoid-type fibromatosis: imaging features and course

Desmoid-type fibromatosis (DF) is a soft tissue tumor characterized by infiltrative growth and a tendency toward local recurrence, while it exhibits self-limiting behavior and shows spontaneous regression. With its unpredictable behavior, a change in treatment strategies from initial surgery to nonsurgical management has been proposed, and active surveillance is currently widely chosen as the initial treatment strategy for DF. We reviewed the imaging features of DF regarding its clinical course, focusing on regression cases, postoperative cases, and imaging changes after systemic treatment.

A case report on atypical spindle cell lipomatous tumor: A rare entity

Introduction

Atypical spindle cell lipomatous tumor (ASPLT), a separate entity for the group of benign/low grade adipocytic neoplasm that is characterized by adipocyte adequacy and the presence of lipoblast-like cells and spindle cells at varying degrees.

Case presentation

Here, we report a rare case of 60 years old male with atypical spindle cell lipomatous tumor in the anterior abdominal wall.

Discussion

Histopathology is the gold standard for establishing the diagnosis and grade of soft tissue tumor and consistent radiology-pathology correlation is essential to avoid any diagnostic pitfalls [1]. Ultrasound is preferred as an initial investigation for superficially located lesions.

Conclusion

ASPLT show a wide variety of microscopic features, and differential diagnosis is important and difficult. Recognition of morphologic clues and immunohistochemistry/molecular tests to confirm the diagnosis.

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Histopathology is the gold standard for establishing the diagnosis and grade of soft tissue tumor.

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Ultrasound is preferred as an initial investigation for superficially located lesions.

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Atypical spindle cell lipomatous tumor (ASPLT), a separate entity for the group of benign/low grade adipocytic neoplasm.

Primary intra-testicular rhabdomyosarcoma: Case report

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Intra-testicular localization of rhabdomyosarcoma remains exceptional and few cases have been reported in the literature.

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Anatomopathological examination is the gold standard for diagnosis and for confirming the intratesticular origin

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Radical inguinal orchiectomy followed by chemotherapy is the treatment of choice.

Giant Cell Tumor of Soft Tissue-A Rare Cause of Mass in the Liver: A Case Report

Primary giant cell tumors of soft tissues (GCT-STs) are extremely rare soft tissue tumors located both in superficial and in deep soft tissues. Clinically, GCT-ST manifests as a slow-growing, well-defined, painless mass. We report a case of an 88-year-old female patient with upper abdominal distension, fever, and anemia. Laparoscopic exploration revealed a tumor located in the left lobe of the liver with localized rupture and hemorrhage. Postoperative pathology revealed that the tumor was composed of monocytes and osteoclast-like multinucleated giant cells, accompanied by extensive hemorrhage, necrosis, and cytologic atypia. Because mitotic cells are difficult to be detected in pathological diagnosis, combined with immunohistochemistry, the tumor was diagnosed as a giant cell tumor of soft tissue. This case report highlights the primary choice of histology and immunohistochemistry for the correct diagnosis of GCT-ST because preoperative radiological diagnosis is nonspecific and prone to mistakes.

An Atypical Pleomorphic Lipomatous Tumor Presenting As Groin Mass

Cutaneous tumors with adipocyte differentiation are frequently excised by surgeons in their daily clinical practice and sometimes less common histological diagnoses arise. Knowledge of different pathological entities and their natural history is essential for better patient management.

Atypical spindle cell/Pleomorphic lipomatous tumor (ASPLT) is a recent group included in the WHO classification. We report a case of a middle-aged man with an atypical pleomorphic lipomatous tumor in an unusual location.