Intra-articular calcifying synovial sarcoma mimicking synovial chondromatosis

Intercondylar Notch Pathology

The intercondylar notch of the knee is a relatively small area. However, numerous rare pathologies can arise in this region. A majority of the existing literature has focused on the cruciate ligament injuries, yet there are several other entities that can cause knee pain from within the intercondylar notch. This review focuses on identifying the various diagnostic and treatment options for rare benign and malignant lesions including ganglion cyst formation, mucoid degeneration, benign proliferative conditions, and intra-articular tumors. These entities are most often diagnosed with advanced imaging studies and treated arthroscopically. While rare, these pathologies are important to identify in patients with ongoing vague knee pain.

Synovial Sarcoma in the Extremity: Diversity of Imaging Features for Diagnosis and Prognosis

Synovial sarcomas are rare and highly aggressive soft-tissue sarcomas, primarily affecting adolescents and young adults aged 15-40 years. These tumors typically arise in the deep soft tissues, often near the large joints of the extremities. While the radiological features of these tumors are not definitely indicative, the presence of calcification in a soft-tissue mass (occurring in 30% of cases), adjacent to a joint, strongly suggests the diagnosis. Cross-sectional imaging characteristics play a crucial role in diagnosing synovial sarcomas. They often reveal significant characteristics such as multilobulation and pronounced heterogeneity (forming the "triple sign"), in addition to features like hemorrhage and fluid-fluid levels with septa (resulting in the "bowl of grapes" appearance). Nevertheless, the existence of non-aggressive features, such as gradual growth (with an average time to diagnosis of 2-4 years) and small size (initially measuring < 5 cm) with well-defined margins, can lead to an initial misclassification as a benign lesion. Larger size, older age, and higher tumor grade have been established as adverse predictive indicators for both local disease recurrence and the occurrence of metastasis. Recently, the prognostic importance of CT and MRI characteristics for synovial sarcomas was elucidated. These include factors like the absence of calcification, the presence of cystic components, hemorrhage, the bowl of grape sign, the triple sign, and intercompartmental extension. Wide surgical excision remains the established approach for definitive treatment. Gaining insight into and identifying the diverse range of presentations of synovial sarcomas, which correlate with the prognosis, might be helpful in achieving the optimal patient management.

Sarcoma Happens: A Reminder for Arthroscopic Surgeons

Primary intra-articular sarcomas are rare and present with nonspecific symptoms such as pain or swelling. Due to nonspecific symptoms, patients may undergo routine diagnostic arthroscopy, which ultimately leads to sarcoma diagnosis. Here we present four patients with intra-articular sarcomas of the knee diagnosed after arthroscopy. The goal of this study is to highlight the importance of including malignant bone and soft-tissue sarcomas in the differential diagnosis of patients with nonspecific knee symptoms. A case series was developed from a retrospective review of prospectively collected data from our institution's orthopedic oncology database. Patients who underwent arthroscopic procedures on the knee and who were diagnosed with intra-articular sarcomas postoperatively from 2014 to 2019 were identified. All patients underwent diagnosis, staging, and multidisciplinary evaluation and treatment. Clinical characteristics, oncologic considerations, and surgical outcomes are described. Four patients with intra-articular sarcomas of the knee diagnosed after arthroscopy for non-oncologic concerns were identified: two synovial sarcomas, one Ewing sarcoma of bone, and one osteosarcoma. All surgical plans and treatment options were significantly affected by the previous arthroscopic procedures. One patient underwent above-the-knee amputation; one patient underwent extra-articular wide resection of the knee, including portal sites with distal femur/total knee reconstruction; one patient underwent rotationplasty, and one patient was treated with therapeutic radiation (no surgery). All patients received chemotherapy. Although intra-articular sarcomas are rare, orthopaedic surgeons must remain vigilant when proceeding with arthroscopic procedures if the clinical history, physical exam, and imaging findings are not perfectly aligned.

Pretreatment Inflammatory Indexes as Prognostic Predictors of Survival in Patients Suffering From Synovial Sarcoma

Background: Inflammatory indexes have been considered as important prognostic factors in various types of cancers. This study aimed to evaluate prognostic values of neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR) in patients with synovial sarcoma (SS). Methods: One hundred and three patients diagnosed with SS were collected during 2006-2017 and divided into high or low NLR, PLR, and LMR groups based on receiver operating characteristic curve analysis. Data of clinical variables were collected for univariate and multivariate analyses. The Kaplan-Meier method was used to analyze OS and PFS of SS patients and significance was evaluated by the log-rank test. Results: The optimal cut-off values of NLR, PLR, and LMR were 2.70, 154.99, and 4.16, respectively. Univariate analyses identified resection surgery, distant metastasis, NLR, PLR, and LMR as the potential predictors of progression-free survival (PFS) and overall survival (OS). In the multivariate analyses, NLR was independent predictors for OS (HR 5.074, 95% CI 1.200-21.463, p = 0.027). Resection surgery, metastasis and LMR was independent predictors for PFS (HR 5.328, p = 0.017; HR 3.114, p = 0.04 and HR 0.202, p = 0.025, respectively). Conclusion: Resection surgery, distant metastasis, NLR, and LMR were independent prognostic factors of PFS and OS in patients with synovial sarcoma. Surgery as an effective treatment strategy, other than radiotherapy and chemotherapy, can significantly prolong survival of synovial patients. Clinical utility of these inflammatory biomarkers should be validated in a larger sample size study.

Primary intra-articular sarcoma: a clinicopathological study of 15 cases

AIMS

To assess the clinical and histopathological spectrum of primary intra-articular sarcomas.

METHODS AND RESULTS

Fifteen patients were identified as having primary intra-articular sarcomas and the clinical and pathological features were evaluated. There were nine males and six females who ranged in age from 16 to 84 (mean 44) years. All tumours originated in the knee joint. The pathological diagnoses included: five synovial sarcoma, three extraskeletal myxoid chondrosarcomas, two high-grade myxofibrosarcoma (one conventional, one epithelioid), two undifferentiated pleomorphic sarcoma (one with giant cells) and one each myxoinflammatory fibroblastic sarcoma, conventional hyaline chondrosarcoma, and high-grade myofibroblastic sarcoma. All tumours were treated by segmental resection or amputation. Adjuvant therapy was given in selected cases. Follow-up ranged from 11 to 150 months. Of patients with follow-up, two died of disease; one developed pulmonary metastases after 6 years and was then lost to follow-up. Nine patients were alive and free of disease 12-150 months after diagnosis.

CONCLUSIONS

Primary sarcomas of the joints are very rare and most frequently affect the knee. Our experience indicates that synovial sarcoma and extraskeletal myxoid chondrosarcoma are the most common intra-articular sarcomas.

Intra-Articular Synovial Sarcomas: Incidence and Differentiating Features from Localized Pigmented Villonodular Synovitis

Purpose. To determine the incidence of intra-articular synovial sarcomas and investigate if any radiological variables can differentiate them from localized (unifocal) pigmented villonodular synovitis (PVNS) and if multivariate data analysis could be used as a complementary clinical tool. Methods. Magnetic resonance images and radiographs of 7 cases of intra-articular synovial sarcomas and 14 cases of localized PVNS were blindedly reviewed. Variables analyzed were size, extra-articular growth, tumor border, blooming, calcification, contrast media enhancement, effusion, bowl of grapes sign, triple signal intensity sign, synovial low signal intensity, synovitis, age, and gender. Univariate and multivariate data analysis, the method of partial least squares-discriminant analysis (PLS-DA), were used. Register data on all synovial sarcomas were extracted for comparison. Results. The incidence of intra-articular synovial sarcomas was 3%. PLS-DA showed that age, effusion, size, and gender were the most important factors for discrimination between sarcomas and localized PVNS. No sarcomas were misclassified as PVNS with PLS-DA, while some PVNS were misclassified as sarcomas. Conclusions. The most important variables in differentiating intra-articular sarcomas from localized PVNS were age, effusion, size, and gender. Multivariate data analysis can be helpful as additive information to avoid a biopsy, if the tumor is classified as most likely being PVNS.

Synovial sarcoma presenting as an avascular mass: radiologic-pathologic correlation

Synovial sarcoma is a well-recognized soft tissue malignancy that typically arises in young adults. It is now generally accepted that its origin is likely from undifferentiated mesenchymal tissue with variable epithelial differentiation and a highly specific chromosomal translocation in more than 95% of cases. The lesion typically presents as a slow-growing soft tissue mass, with MR imaging demonstrating a heterogeneous mass with variable amounts of low-, intermediate- and high-signal intensity on fluid-sensitive images and prominent heterogeneous enhancement, reflecting its vascularity. The relative hypervascularity of synovial sarcoma has been well established and is reflected in its enhancement on MR imaging studies. Contrast enhancement on MR imaging has been long used as a marker for tissue vascularization and perfusion, with malignant lesions generally being more vascular and enhancing more rapidly. We recently encountered a patient with a high-grade synovial sarcoma with no discernable necrosis and no vascularity on contrast-enhanced MR images with the subtraction technique, despite enhancement in adjacent regional metastatic lymph nodes. The pathologic basis for this unusual imaging appearance was a paucity of small-caliber vessels within the sarcoma due to extensive hyalinization of the mass.

Synovial sarcoma: defining features and diagnostic evolution

Synovial sarcoma (SS) is a malignant mesenchymal neoplasm with variable epithelial differentiation, with a propensity to occur in young adults and which can arise at almost any site. It is generally viewed and treated as a high-grade sarcoma. As one of the first sarcomas to be defined by the presence of a specific chromosomal translocation leading to the production of the SS18-SSX fusion oncogene, it is perhaps the archetypal "translocation-associated sarcoma," and its translocation remains unique to this tumor type. Synovial sarcoma has a variety of morphologic patterns, but its chief forms are the classic biphasic pattern, of glandular or solid epithelial structures with monomorphic spindle cells and the monophasic pattern, of fascicles of spindle cells with only immunohistochemical or ultrastructural evidence of epithelial differentiation. However, there is significant morphologic heterogeneity and overlap with a variety of other neoplasms, which can cause diagnostic challenge, particularly as the immunoprofile is varied, SS18-SSX is not detected in 100% of SSs, and they may occur at unusual sites. Correct diagnosis is clinically important, due to the relative chemosensitivity of SS in relation to other sarcomas, for prognostication and because of the potential for treatment with specific targeted therapies in the near future. We review SS, with emphasis on the diagnostic spectrum, recent immunohistochemical and genetic findings, and the differential diagnosis.

Intra-articular synovial sarcoma

A case of right knee intra-articular synovial sarcoma in a 26-year-old man is reported. The patient had experienced 12 to 18 months of chronic posterior right knee pain with flexion contracture of the leg. Magnetic resonance imaging (MRI) examination demonstrated nonspecific characteristics of a well-circumscribed, homogeneous mass within the posterior lateral compartment of the knee joint. The mass was isointense and hyperintense to muscle on T1- and T2-weighted sequences respectively, and initially clinically diagnosed as a localized tenosynovial giant cell tumor. However, histological examination showed the lesion to be a synovial sarcoma arising from the synovium of the knee joint. Synovial sarcoma may have a nonspecific MR appearance, especially when less than 5 cm in size, often simulating a less aggressive process. Primary intra-articular origin may predispose to earlier presentation, and therefore, radiological evaluation of smaller masses. Nonspecific MR characteristics of small, intra-articular masses provide a diagnostic dilemma. Synovial sarcoma should be considered in the differential diagnosis when distinguishing MR characteristics of other common joint-centered entities are not present.

Synovial sarcoma of the buccal mucosa: a rare case report

Synovial sarcoma (SS) is a rare malignant neoplasm that arises most commonly in joint capsules and articular tendons, but its relationship to the synovium is not always obvious. Synovial sarcoma is a malignant soft tissue tumor representing 5.6% to 10% of all soft tissue sarcomas. They are termed SS because of their histologic resemblance to the synovium, but they rarely involve a synovial structure and are thought to arise from pluripotential mesenchymal cells. The tumor usually occurs in close association with tendon sheaths, bursae, and joint capsules, primarily in the para-articular regions of the extremities, with approximately 9% occurring in the head and neck region. Synovial sarcoma has been reported rarely in the oral cavity. We report a very rare case of Synovial sarcoma of the buccal mucosa in a 24-year-old male patient.

Magnetic resonance imaging of malignant soft tissue neoplasms in the adult

This review addresses the spectrum of malignant soft tissue tumors frequently found in adults. Rather than presenting a complete review, the focus of this discussion is on common lesions or lesions in which the diagnosis may be suggested on the basis of imaging. Diagnoses covered include undifferentiated high-grade pleomorphic sarcoma, fibrosarcoma, dermatofibrosarcoma protuberans, liposarcoma, synovial sarcoma, malignant peripheral nerve sheath tumor, clear cell sarcoma, hemangioendothelioma, hemangiopericytoma, angiosarcoma, and leiomyosarcoma.

Tumors and diseases of the joint

A variety of different diseases affect the synovium, including infection, noninfectious immunologic inflammatory conditions, degenerative arthroses, crystal deposits, trauma, and tumors. Tumors of the synovium are relatively uncommon. Any mesenchymal tumor may arise in the synovium, but most recapitulate its normal counterpart including synoviocytes, blood vessels, fat, and fibrous tissue. These tumors can arise in any synovial lined structures both within joints and in extraarticular locations. Most synovial tumors are benign. Malignant tumors are rare but important to recognize because many are aggressive and must be treated appropriately. Among common nonneoplastic conditions that affect the synovium and surrounding structures are crystal deposits such as monosodium urate crystals, calcium pyrophosphate dihydrate crystals, and hydroxyapatite crystals. These crystal deposits may be asymptomatic or cause severe pain or chronic joint destruction. Their accurate identification is important to guide appropriate therapy.

High-grade intra-articular liposarcoma of the knee

A high-grade pleomorphic intra-articular liposarcoma of the knee is described in a 48-year-old man, which was diagnosed histologically after arthroscopy of the knee for suspected pigmented villonodular synovitis (PVNS). The patient proceeded to undergo an extra-articular resection with a custom-made prosthesis. This report highlights the need to remember this rare tumour in the differential diagnosis of atypical soft tissue lesions within the knee joint prior to instrumentation.

Tumour and tumour-like lesions of the intercondylar notch of the knee: a pictorial review

A variety of tumours and tumour-like lesions are found in the intercondylar notch of the knee. MR imaging is the technique of choice in evaluating these conditions. Correlation with radiographs is important to identify those lesions containing calcification. This review article discusses the imaging features of tumour and tumour-like lesions involving the intercondylar notch with an emphasis on MR imaging features that suggest a specific diagnosis.

MRI features of three paediatric intra-articular synovial lesions: a comparative study

AIM

To determine reliable magnetic resonance imaging (MRI) features differentiating three paediatric intra-articular congenital or neoplastic synovial lesions that contain blood products, from post-traumatic or haemorrhagic inflammatory processes.

MATERIALS AND METHODS

This was a retrospective review of MRI findings of 22 paediatric intra-articular congenital or neoplastic synovial lesions, including venous malformation (VM) (n=12), pigmented villonodular synovitis (PVNS; n=8), and synovial sarcoma (SS; n=2). These MRI features were compared with 22 paediatric post-traumatic or inflammatory intra-articular processes containing blood products and producing mass effect. The following imaging features were assessed: presence of a discrete mass, extension, extra-articular oedema, susceptibility, joint effusion, and size. Fisher's exact test was used and results were considered statistically significant when p<0.05.

RESULTS

The three intra-articular synovial lesions, compared with controls, were more likely to directly invade osseous structures when a discrete mass was present (13/16, 81.3% versus 1/9, 11.1%; p<0.002) and extend into extra-articular soft tissues (13/21, 61.9% versus 2/17, 11.8%; p<0.003), but were less likely to show extra-articular oedema (3/22, 13.6% versus 13/22, 59.1%; p<0.004), a joint effusion (10/22,45.5% versus 19/22, 86.4%, p<0.01), susceptibility within a joint effusion (0/22, 0% versus 11/22, 40.9%; p=0.00), osseous oedema (3/16, 18.8% versus 7/9, 77.8%; p<0.009), and synovial enhancement (8/21, 38.1% versus 14/16, 87.5%; p<0.003). VMs had characteristic tubular vessels with internal fluid-fluid levels (11/12) that extended into bone (10/12) and extracapsular soft tissues (11/12).

CONCLUSION

Our study indicates that, despite the overlapping presence of haemorrhagic products, intra-articular VM, PVNS, and SS show MRI features that permit distinction from acquired post-traumatic and haemorrhagic inflammatory lesions.

Radiological features of synovial cell sarcoma

Synovial cell sarcoma is an uncommon soft-tissue malignant tumour. These tumours have common radiological features with a variety of both benign and malignant lesions. However, there is a variety of imaging findings that can suggest a pre-biopsy diagnosis of synovial cell sarcoma. This pictorial review aims to describe the imaging features of synovial sarcoma in a series of cases with various age ranges and tumour locations. In addition, the pathology, staging, prognosis and management of synovial sarcoma is briefly discussed.

Intraarticular synovial sarcoma confirmed by SYT-SSX fusion transcript

A case of intraarticular synovial sarcoma arising in the knee verified by detection of the tumor-specific SYT-SSX fusion transcript is described. Although it is extremely rare, synovial sarcoma may occur entirely within a joint space. The molecular assay for detecting a tumor-specific chimeric gene is a valuable tool for diagnosis of soft tissue sarcoma, especially for diagnostically difficult cases and tumors in unusual locations.

Multiple giant synovial chondromatosis of the knee

This report describes an unusual presentation of monoarticular synovial chondromatosis of the knee. In this case, multiple giant chondroid nodules presented as a painless soft tissue mass. There was no calcification but bony erosion was seen on MR scan. Such lesions may mimic a malignant neoplasm and pose a diagnostic problem.