Primary cardiac synovial sarcoma originating from the atrial septum and associated pulmonary infarction: a case report.

BACKGROUND: Primary cardiac synovial sarcoma is a rare condition with limited treatment options for advanced stages. Surgery and chemotherapy are currently the mainstay treatments; however, survival rates remain low. CASE PRESENTATION: A 64-year-old woman presenting with symptoms of chest tightness and shortness of breath was found to have an obstructive right atrial mass, along with pulmonary infarction and metastasis. She was ultimately diagnosed with advanced primary cardiac synovial sarcoma. Following surgery, the patient's symptoms improved, and she underwent chemotherapy and anti-angiogenic therapy, but unfortunately, her survival time was only 8 months. CONCLUSION:  This case report aims to enhance clinicians' understanding of the diagnosis and treatment of primary cardiac synovial sarcoma. Enhancing both survival outcomes and quality of life in individuals with primary cardiac synovial sarcoma continues to present a significant challenge.

Rare mediastinal small round cell melanoma with synovial sarcoma-like immunophenotype: A potential diagnostic pitfall.

Melanoma can pose a significant diagnostic challenge due to the high variability in histological morphology and expression of non-melanocytic immunomarkers. We present a case of a 47-year-old male with an aggressive mediastinal neoplasm and disseminated disease posing several diagnostic challenges. Multiple biopsies were submitted from different anatomic locations and during multiple time points showing an undifferentiated round cell tumor (URCT) with synovial sarcoma-like immunophenotype. SS18::SSX fusion was sought through NGS study for diagnostic confirmation. NGS results revealed NRAS and CDKN2A mutations and absence of fusions, resulting in a new review of the histologic material with a broader immunohistochemical panel, finding strong positivity to melanic antibodies. This case is an illustrative example of a malignant melanoma with small round cell morphology showing aberrant expression of CD99, BCL2, TLE1 and SS18-SSX antibodies exposing a potentially hazardous pitfall highlighting the importance of a wide differential diagnosis and the role of confirmational studies with molecular tests.

Giant Common Peroneal Nerve Schwannoma Mimicking Synovial Sarcoma: An Unusual Case Report.

Schwannoma, also known as neurilemmoma or Schwann cell tumor, is one of the most common neoplasms of the nerve sheath which usually appears at the head, neck, or upper extremity. Schwannoma occurrence in the lower extremity originating from the common peroneal nerve is rarely reported according to literary findings. We report a case of a 32-year-old man who presented with a 6-month history of a growing lump in the left knee. MRT revealed a well-defined 9.6 cm × 7.8 cm × 6.5 cm multilobular mass of heterogeneous consistency with areas of necroses with a likely diagnosis of synovial sarcoma. After surgery, a final histopathological assessment of the tumor demonstrated Antoni A and B patterns with nuclear palisading, hallmarks of a schwannoma. Postoperatively the patient suffered a neurological complication-impaired dorsiflexion of the left foot. The patient started immediate physiotherapy in the Department of Rehabilitation. Three weeks after the operation, gradual improvement in neurological function was observed. To date, complete tumor excision combined with microscopic analysis and immunohistochemical staining remains the gold standard in diagnosing and treating a peripheral nerve schwannoma. Moreover, the use of additional nerve monitoring tools during surgery could help to prevent complications.

Tonsillar synovial sarcoma, unusual anatomical location: case report and literature review.

BACKGROUND: Synovial sarcoma is a rare soft tissue malignancy, occasionally found in the head and neck region. The diagnosis necessitates a multidisciplinary approach involving the clinical presentation, proper imaging studies and histological confirmation, with molecular testing for definitive identification. Treatment entails surgical resection with adjuvant therapies as needed. CASE PRESENTATION: A 33-year-old male patient presented with globus sensation concomitant with right-sided neck swelling. He was clinically found to have right tonsil enlargement with posterior extension. Therefore, he underwent right tonsillectomy with pharyngoplasty. Histopathological examination revealed a biphasic tumor consistent with synovial sarcoma, confirmed by immunohistochemistry and fluorescence in situ hybridization. CONCLUSIONS: Tonsillar synovial sarcoma represents a diagnostic challenge, requiring a high index of suspicion and comprehensive evaluation. With only twenty previously published cases documented in the literature, awareness of this rare presentation is crucial for prompt diagnosis and appropriate management. Collaboration among multidisciplinary healthcare teams and ongoing research efforts are essential for optimizing diagnostic accuracy, treatment efficacy, and patient outcomes in this rare malignancy.

Synovial Sarcoma of the Kidney: Diagnostic Pitfalls in a Case with Myxoid Monophasic Differentiation and No Epithelial Biomarkers Expression.

Synovial sarcomas are soft tissue tumours of uncertain origin, most commonly found in the upper or lower extremities. They are characterised by distinctive chromosomal rearrangements involving the gene SS18. Synovial sarcomas can occasionally arise also in visceral sites, but retroperitoneal SSs are very unusual. Among them, a few primary renal synovial sarcomas have been described in the scientific literature. Primary renal synovial sarcomas tend to be monophasic and often show cystic changes. Histologically, they can closely resemble other primary kidney tumours, mainly paediatric tumours such as nephroblastoma and clear cell sarcoma of the kidney. In the current work, a primary synovial sarcoma of the kidney with unusual morphological features (extensively myxoid stroma and immunohistochemical positivity for BCOR) is described. Molecular analysis, through targeted RNA sequencing, was of invaluable help in reaching the correct diagnosis. Despite locally advanced disease at presentation, the patient showed an unexpectedly brilliant response to chemotherapy.

Synovial myxosarcoma in the scapulohumeral joint of a dog: a case report.

A 12-year-old, 3 kg spayed female mixed-breed dog was evaluated to assess a 1-year history of intermittent right forelimb lameness that did not have adequate response to nonsteroidal anti-inflammatory drugs. The radiographic study performed under sedation showed multifocal radiolucent areas affecting both the right humerus and scapula with focal soft tissue swelling; a CT scan confirmed the existence of an aggressive and invasive soft tissue mass affecting the scapulohumeral joint. Fine needle aspiration results suggested a low-grade synovial sarcoma and therefore a scapulectomy was performed. The biopsy showed spindle to stellated cells immersed in a basophilic and mucinous (myxoid) matrix with mild to moderate anisocytosis, moderate anisokaryosis, some binucleated cells and sporadic multinucleated cells. These findings are consistent with low-grade synovial myxosarcoma, a not well described synovial neoplasm that can mimic other commonly seen joint tumors or even septic arthritis on radiographs. The purpose of this case report is to describe the first reported synovial myxosarcoma affecting the scapulohumeral joint of a small dog.

A giant synovial sarcoma of the left lung.

Primary pulmonary synovial sarcoma is an extremely rare and aggressive neoplasm that primarily affects young people and has a poor prognosis. Establishing this diagnosis requires the exclusion of a wide number of other neoplasms with multimodal clinical, imaging, histological, immunohistochemical, and cytogenetic assessment. We present a case of synovial sarcoma of the left lung in a 44-year-old man, diagnosed immunohistochemically after left lower lobectomy with atypical resection of the 5th segment. Imaging, diagnostic workup, histological and immunohistochemical characteristics, surgical treatment, and prognosis are discussed.

[Imaging characteristics and diagnosis of primary middle mediastinal tumors].

Objectives: To investigate the proportion of different histological types and CT enhanced imaging features of primary middle mediastinal lesions in order to improve the understanding of these tumors and the accuracy of preoperative diagnosis. Methods: Retrospective analysis was conducted on 84 patients with primary middle mediastinal lesions and clear histological classifications diagnosed and treated at the Cancer Hospital, Chinese Academy of Medical Sciences from January 2012 to December 2022. Clinical, imaging, and pathological data were collected and classified according to tumor histological classifications. CT imaging manifestations such as tumor location, size, morphology, edge, boundary, internal components, enhancement characteristics, and surrounding tissue invasion were evaluated and recorded. Results: The histological types of the primary middle mediastinal lesions from the 84 patients included mesenchymal tumors, anterior intestinal cysts, giant lymph node hyperplasia, substernal goiter, neuroendocrine carcinoma, lymphohematopoietic system tumors, and mesothelioma, accounting for 28.6%, 27.4%, 14.3%, 3.6%, 11.9%, 9.5%, and 4.8%, respectively. Mesenchymal tumors included peripheral nerve sheath tumors, vascular tumors, adipogenic tumors, solitary fibrous tumors, and synovial sarcoma, accounting for 54.2%, 20.8%, 12.5%, 8.3%, and 4.2%, respectively. The above tumors had diverse imaging manifestations and specific imaging features. Mature fat were found in 3 cases of liposarcoma; Calcification was observed in 2 cases of thyroid nodules and 7 cases of giant lymph node hyperplasia; Enhanced scanning showed significant enhancement in 2 cases of solitary fibrous tumors, 3 cases of thyroid nodules, and 11 cases of giant lymph node hyperplasia; Mediastinal large lymph nodes was observed in 6 cases of lymphoma and 3 cases of mesothelioma; High invasiveness was observed in 4 cases of mesothelioma and 9 cases of neuroendocrine carcinoma. Conclusion: Mediastinal tumors have low incidence rate and rich histological types, and their imaging manifestations are diverse. Preoperative differential diagnosis can be made according to their specific imaging characteristics.

[Primary cardiac synovial sarcoma: a clinicopathological analysis of five cases].

Objective: To assess the clinicopathological features, immunophenotype, molecular characteristics and differential diagnosis of primary cardiac synovial sarcoma (PCSS). Methods: Five cases of PCSS were collected at Guangdong Provincial People's Hospital from 2008 to 2023, and their clinicopathological features were summarized. Immunohistochemical staining, fluorescence in-situ hybridization (FISH) and next-generation sequencing (NGS) were performed, and relevant literatures were reviewed. Results: The cases were found in four males and one female, ranging in ages from 16 to 51 years (median 30 years). Two cases were located in the pericardium, two in the right ventricle, and one in the left ventricle. Follow-up data were available in four cases. All the four patients died of disease at 3, 7, 13 and 26 months, respectively, after diagnosis. The tumor maximum diameter ranged from 6.0 to 14.0 cm in (mean 10.0 cm). Microscopically, three cases were monophasic and two cases were biphasic. Immunohistochemically, all cases were immunoreactive for EMA, vimentin, bcl-2 and CD56. The tumor cells were variably positive for pan-cytokeratin, SS18-SSX, SOX2, TLE1, CD99, synaptophysin, calretinin and calponin. FISH showed the presence of SS18 rearrangement in all the cases. NGS detected SS18-SSX gene fusion in three cases (SS18-SSX1 in one and SS18-SSX2 in two). Conclusions: PCSS is an exceedingly rare neoplasm, and should be distinguished from other various malignant epithelial and mesenchymal tumors. The clinical history, histopathological and immunohistochemical features, and molecular findings are all essential to the definitive diagnosis of PCSS.

Complete resection of a giant intrapericardial cardiac synovial sarcoma.

Synovial sarcoma of the heart is a rare tumor. Herein we would like to report a case of giant intrapericardial cardiac synovial sarcoma that originated from the right ventricle and grew outward near the diaphragm. After making adequate preoperative preparation, we performed the surgery as quickly as possible and resected the tumor completely. Based on the identification of the translocation on chromosome 18 rearrangement, the tumor can be diagnosed as a primary cardiac synovial sarcoma. Through this study, we aim to afford more information about cardiac synovial sarcomas as well as a reference for similar cases.

Synovial sarcoma of the viscera (lung and jejunum): a case report.

We report the case of a woman nearing 70 years old who was admitted to the hospital with a complaint of "epigastric distension for 1 month". Her main signs and symptoms were progressive abdominal distension and occasional abdominal pain. Computed tomography suggested an abdominal mass. She had a surgical history of synovial sarcoma (SS) of the lungs. After admission, she was diagnosed with jejunal SS following a puncture biopsy and laparoscopic surgery. This disease usually occurs in the soft tissues of the limbs, and it is extremely rare for SS to originate in the jejunum. The morphologic heterogeneity of SS overlaps with other tumors and makes the diagnosis particularly difficult. Imaging studies usually lack specificity; however, measuring multiple immunohistochemical markers can greatly assist in the diagnosis and differential diagnosis of SS. This case not only enriches our understanding of SS and describes a rare site of origin, but also emphasizes the importance and challenges of achieving an accurate diagnosis. Immunohistochemical and molecular biological testing have important roles in the definitive diagnosis, highlighting the need for precise and innovative diagnostic and therapeutic approaches in SS.

Early Diagnosis of Rare Diaphragmatic Synovial Sarcoma in a Pediatric Patient With Epigastric Pain Using Point-of-Care Ultrasound.

ABSTRACT: Synovial cell sarcoma is a rare mesenchymal tumor that typically originates from the soft tissues of the extremities of young adults. Only 3 cases of primary diaphragmatic synovial cell sarcoma have been described in the literature: 2 in adult males and 1 in a 12-year-old pediatric patient. 1-3 When this tumor is found in the mediastinum or pericardial region, prognosis is historically poor because of the advanced disease stage at time of diagnosis. The surgical course and pathology have been described in this 12-year-old boy. 3 This is the first case, to our knowledge, of the use of cardiac point-of-care ultrasound in the early identification and diagnosis of a primary diaphragmatic synovial sarcoma in a pediatric patient.

Recurrent Synovial Sarcoma with Breast and Pulmonary Nodule: A Case Report.

Synovial sarcoma is a mesenchymal tumour with partial epithelial differentiation. About 85-90% of SS occur in the extremities. We present a case of a 44-year-old woman diagnosed with recurrent synovial sarcoma with breast and pulmonary nodules. The primary treatment for synovial sarcoma is wide surgical excision, while chemotherapy is reserved for metastatic cases. In the first-line metastatic setting, combination treatment with adriamycin and ifosfamide is administered. Despite the unfavourable prognosis, the patient's extended survival is fortunately not the typical outcome. Keywords: case reports; chemotherapy; immunohistochemistry; synovial sarcoma.

[Renal synovialosarcoma: What about pyelic cytology to make a diagnosis?] / Synovialosarcome primitif du rein : si tout était déjà dans les urines pyéliques ?

Synovialosarcoma is a malignant mesenchymal tumor of young adults that occurs in the deep soft tissues, particularly around large joints. When it occurs in more unusual sites, it could present a significant diagnostic challenge. In this case, a 19-year-old girl was treated for a pyloric mass. A pyelic urine cytology performed simultaneously with a pyloric biopsy proved to be a significant element of orientation and perfectly concordant with the histopathological aspect of the pyelic mass after nephrectomy. We report here the first case of renal synovialosarcoma documented in pyelic urine.

Poorly differentiated biphasic synovial sarcoma of the vulva, displaying SS18::SSX1 fusion and weak to absent (mosaic) INI1/SMARCB1 immunostaining: A rare case with literature review.

ABSTRACT: Synovial sarcoma (SS) is rarely documented in the female genital tract, especially confirmed by molecular testing for SYT::SSX translocation and TLE1 immunostaining. A 62-year-old lady presented with a progressively increasing lump and pain over her right groin, for 6-month duration. Radiologically, a well-defined, solid-cystic mass was seen involving the right labia with necrotic areas, sparing the underlying muscles and the overlying skin. She underwent a biopsy followed by a surgical excision. Histopathologic examination revealed a spindle cell sarcoma, including tumor cells exhibiting a prominent hemangiopericytomatous pattern. There were focal areas of epithelial differentiation (pseudoglandular) along with areas of round cell morphology and increased mitoses (poor differentiation) in the resected specimen. Immunohistochemically, the tumor cells were diffusely positive for TLE1, patchily positive for pan keratin (AE1/AE3) and EMA, the latter more in the areas of epithelial differentiation, while negative for CD34, SMA, desmin, S100P, and SOX10. INI1/SMARCB1 showed a characteristic weak to absent (mosaic) staining pattern. Furthermore, the tumor displayed SS18::SSX 1 fusion by RT-PCR. This constitutes one of the few reported cases of vulvar SS, confirmed by molecular testing and the first documented vulvar SS showing a mosaic pattern of INI1/SMARCB1 immunostaining. A review of the literature and diagnostic implications are presented herewith.

Biphasic synovial sarcoma with epithelial predominance reminiscent of adenocarcinoma: a diagnostic challenge.

Synovial sarcoma (SS) is a rare tumour of unknown origin with peak incidence between 10 and 35 years. Although it arises in juxta-articular location, SS is a misnomer and has no true relationship with synovium. In this case report, we present an elderly female patient with a long-standing history of thigh mass which was initially misdiagnosed as metastatic adenocarcinoma deposits on fine needle aspiration cytology, and again misdiagnosed as malignant adnexal skin tumour on core needle biopsy and referred for further management. Here, we discuss the challenges faced in the diagnosis of SS on a small biopsy and ways to differentiate it from other morphological mimickers. Therefore, we aim to increase the awareness of soft tissue tumours that microscopically appear like adenocarcinoma, which is a potential diagnostic pitfall. We also highlight the importance of morphological diagnosis and the utility of molecular testing using fluorescence in situ hybridisation, to arrive at the correct diagnosis of SS.

TLE1 Expression in NUT Carcinoma: A Case Report Highlighting a Potential Diagnostic Pitfall for the Pathologist.

NUT carcinoma is a rare, aggressive malignancy defined as a carcinoma with a chromosomal rearrangement affecting the nuclear protein in testis (NUTM1) gene. This small round blue cell tumor classically exhibits focal abrupt keratinization and immunohistochemical positivity for keratin and squamous markers. However, keratinization is not always present and reports of positivity for other markers that may obscure the diagnosis are increasing. It is also noteworthy that gene fusions involving NUTM1 are not restricted to NUT carcinoma. Herein, we report a NUT carcinoma arising in the mediastinum of a male patient in his 40 s with morphological and immunohistochemical overlap with Ewing family sarcoma and poorly differentiated synovial sarcoma given a round cell morphology, diffuse strong immunoreactivity for CD99, and patchy strong immunoreactivity for TLE1. Squamous differentiation by morphology and p40 expression were notably absent in this case. Classification as NUT carcinoma was ultimately possible when the morphological and immunohistochemical findings were considered in the context of a BRD4::NUTM1 gene fusion identified by next-generation sequencing. While the patient initially responded to palliative radiotherapy, he died approximately one month later. To our knowledge, this is the first report of TLE1 immunoreactivity in NUT carcinoma. This case highlights a potential diagnostic pitfall and emphasizes the need for molecular confirmation in equivocal situations.

Diagnostic Utility of GATA3 and ISL1 in Differentiating Neuroblastoma From Other Pediatric Malignant Small Round Blue Cell Tumors.

Accurate diagnosis of neuroblastoma may be challenging, especially with limited or inadequate specimen and at the metastatic sites due to overlapping imaging, histopathologic, and immunohistochemical (immunohistochemistry [IHC]; infidelity among various lineage-associated transcription factors eg FLI1, transducin-like enhancer 1, etc) features. GATA3 and ISL1 have recently been described as markers of neuroblastic differentiation. This study aims at determining the diagnostic utility of GATA3 and ISL1 in differentiating neuroblastoma from other pediatric malignant small round blue cell tumors.We evaluated GATA3 and ISL1 expression in 74 pediatric small round blue cell tumors that included 23 NMYC-amplified neuroblastomas, 11 EWSR1-rearranged round cell sarcomas, 7 SYT::SSX1-rearranged synovial sarcomas, 5 embryonal rhabdomyosarcomas, 10 Wilms tumors (nephroblastomas), 7 lymphoblastic lymphoma, 7 medulloblastoma, and 4 desmoplastic small round cell tumor.All 23 neuroblastomas (moderate to strong staining in >50% of the tumor cells), 5 T-lymphoblastic lymphomas (moderate to strong staining in 40%-90% of the tumor cells), and 2 desmoplastic small round cell tumors (weak to moderate staining in 20%-30% of the tumor cells) expressed GATA3, while other tumors were negative. ISL1 immunoreactivity was observed in 22 (96%) neuroblastomas (strong staining in in >50% of the tumor cells, n = 17; moderate to strong staining in 26%-50% of the tumor cells, n = 5), 3 embryonal rhabdomyosarcoma (moderate to strong staining in 30%-85% of the tumor cells), 1 synovial sarcoma (weak staining in 20% of the tumor cells), and 7 medulloblastoma (strong staining in 60%-90% of the tumor cells). Other tumors were negative. Overall, GATA3 showed 86% specificity, 100% sensitivity, and 90% accuracy for neuroblastoma, with a positive predictive value (PPV) and negative predictive value (NPV) of 77% and 100%, respectively. ISLI showed 72% specificity, 96% sensitivity, and 81% accuracy for neuroblastoma, with a PPV and NPV of 67% and 97%, respectively. After the exclusion of T-lymphoblastic lymphoma and desmoplastic small round cell tumors, GATA3 had 100% specificity, sensitivity, accuracy, and PPV and NPV for neuroblastoma. Similarly, in pediatric small round blue cell tumors, ISL1 had 100% specificity, sensitivity, accuracy, PPV, and NPV for neuroblastoma, after embryonal rhabdomyosarcoma, synovial sarcoma, and medulloblastoma were excluded. CONCLUSIONS: GATA3 and ISL1 may be valuable in the diagnostic work-up of neuroblastoma and may reliably be used to support the neuroblastic lineage of pediatric small round blue cell tumors. Furthermore, dual positivity helps in challenging scenarios, when there is equivocal imaging, overlapping IHC features, limited specimen, and the lack of facility for a molecular work up.

Utility of Immunohistochemistry With Antibodies to SS18-SSX Chimeric Proteins and C-Terminus of SSX Protein for Synovial Sarcoma Differential Diagnosis.

Synovial sarcoma is a relatively common soft tissue tumor characterized by highly specific t(X;18)(p11;q11) translocation resulting in the fusion of SS18 with members of SSX gene family. Typically, detection of SS18 locus rearrangement by fluorescence in situ hybridization or SS18 :: SSX fusion transcripts confirms the diagnosis. More recently, immunohistochemistry (IHC) for SS18-SSX chimeric protein (E9X9V) and C-terminus of SSX (E5A2C) showed high specificity and sensitivity for synovial sarcoma. This study screened a cohort of >1000 soft tissue and melanocytic tumors using IHC and E9X9V and E5A2C antibodies. Three percent (6/212) of synovial sarcomas were either negative for SS18-SSX or had scattered positive tumor cells (n=1). In these cases, targeted RNA next-generation sequencing detected variants of SS18 :: SSX chimeric transcripts. DNA methylation profiles of 2 such tumors matched with synovial sarcoma. A few nonsynovial sarcoma tumors (n=6) revealed either focal SS18-SSX positivity (n=1) or scattered positive tumor cells. However, targeted RNA next-generation sequencing failed to detect SS18 :: SSX transcripts in these cases. The nature of this immunopositivity remains elusive and may require single cell sequencing studies. All synovial sarcomas showed positive SSX IHC. However, a mosaic staining pattern or focal loss of expression was noticed in a few cases. Strong and diffuse SSX immunoreactivity was also seen in epithelioid sclerosing osteosarcoma harboring EWSR1 :: SSX1 fusion, while several sarcomas and melanocytic tumors including cellular blue nevus (5/7, 71%) revealed focal to diffuse, mostly weak to intermediate SSX staining. The SS18-SSX and SSX IHC is a useful tool for synovial sarcoma differential diagnosis, but unusual immunophenotype should trigger molecular genetic testing.