Diagnostic Value of TLE1 in Synovial Sarcoma: A Systematic Review and Meta-Analysis

Primary synovial sarcoma in anal canal: Report of a very rare case

Extensive studies are required to understand the behavior as well as prognosis of SS in the colorectal region. IHC staining is essential for the accurate diagnosis when a lesion is encountered at an unusual site.

Synovial Sarcoma of the Hypopharynx in a Filipino Female: A Case Report

Synovial sarcoma of the hypopharynx is an uncommon malignancy, with less than 100 cases reported in available journals. We report a case of a 22-year-old female presenting with dysphagia and enlarging hypopharyngeal mass, clinically diagnosed as hypopharyngeal malignancy, right, at least stage III. Histopathologic examination including immunohistochemistry study with TLE1 and SS18 Fluorescence In Situ Hybridization (FISH) confirm the diagnosis of synovial sarcoma. This is the first reported case of synovial sarcoma of the hypopharynx in the Philippines confirmed by SS18 FISH. Due to the size of the mass, chemoradiotherapy followed by surgery is the current plan of management for this patient.

Rarest of the Rare - Malignant Solitary Fibrous Tumour of the Breast: Case Report and Literature Review

Malignant solitary fibrous tumor of the breast is one of the rarest types of breast malignancy. To the best of our knowledge, only six cases have been reported so far. Here we have presented such a case from India, where a 52-year-old lady presented with a 10 cm x 8 cm breast lump. Diagnosis was achieved with the help of FDG PET, histopathology and immunohistochemistry, which showed nuclear positivity for STAT6. Fluorescent in situ hybridization (FISH) molecular study for SS18-SSX was used to rule out the differential diagnosis of synovial sarcoma. Guidelines for the management of this type of breast malignancy still do not exist. We have done a review of the literature in order to discuss which might be the best management in such cases. Evidence on this very rarest type of breast malignancy is still evolving. The interest in the case described here relies on its rarity, difficulties in achieving diagnosis and formulation of the proper management.

Unusual Aspects of Small Cell Carcinoma of the Ovary of Hypercalcaemic Type: Retained SMARCA4 Immunohistochemical Staining and Positive Staining With TLE1

Small cell carcinoma of the ovary of hypercalcaemic type (SCCOHT) is a rare and aggressive ovarian neoplasm that is most common in the second and third decades. Molecular studies have established inactivating SMARCA4 alterations as the driver of SCCOHT, these being present in over 95% of these neoplasms. SMARCA4 alterations almost always result in loss of immunoreactivity with SMARCA4 (BRG1) antibody, and this is an extremely useful adjunct in the diagnosis of SCCOHT. Herein, we report 7 cases of SCCOHT (2 from the same patient) with retention of nuclear immunoreactivity with SMARCA4, but with SMARCA4 alterations identified on molecular testing. All cases exhibited loss of SMARCA2 (BRM) immunoreactivity. In addition, following the identification of diffuse TLE1 immunoreactivity in one of these cases (which did not exhibit an SS18 gene rearrangement characteristic of synovial sarcoma), we stained a total of 63 cases of SCCOHT (14 on whole tissue sections: 49 on tissue microarray) with this marker and 7 of 14 (50%) and 22 of 49 (45%) were positive on whole sections and tissue microarray, respectively. Most cases were focally positive but occasional cases exhibited diffuse immunoreactivity. Our observations highlight the importance of SMARCA2 immunohistochemical staining and molecular testing in suspected cases of SCCOHT that exhibit retained SMARCA4 immunoreactivity. Th common expression of TLE1 in these neoplasms represents a potential diagnostic pitfall since synovial sarcoma may be considered in the differential, especially in cases with retained SMARCA4 immunohistochemistry.

Synovial sarcoma of the maxilla: A challenging diagnostic case report and literature review

Synovial sarcoma, a malignant mesenchymal tumor, is primarily associated with the extremities. Nevertheless, its appearance within the head and neck region, particularly in the maxillary area, is remarkably rare. This rarity underscores the significance of each case in unraveling the complexities of its behavior and management strategies. The core focus of this research is a detailed case report involving a 6-year-old female patient who presented with a conspicuous swelling in the left posterior maxilla. Subsequent incisional biopsy led to microscopic identification of malignant spindle cell proliferation, marked by dysplastic changes, and abundant mitoses. Immunohistochemical (IHC) analysis demonstrated negative reactivity for neural and muscular markers, while positive expression of Vimentin, Bcl-2, and TLE1. These morphological and IHC findings coalesced to definitively diagnose synovial sarcoma, substantiated by a notable 40% Ki67 proliferative index. The chosen treatment strategy encompassed surgery and radiotherapy, which yielded successful outcomes, with no recurrence observed during the one-year follow-up period. Beyond the specific case, this article undertakes a review of existing literature, meticulously analyzing nine similar cases reported in scholarly sources.

Expression of TLE1 in a Carcinoid Tumor of the Lung With Spindle Cell Morphology-A Potential Diagnostic Pitfall

Tumors of the lung with a spindle cell morphology require consideration of many entities in the differential diagnosis, including metastases. Ancillary immunohistochemical stains but also molecular studies are typically required to arrive at the proper diagnosis. We present a case of a 71-year-old woman with multiple lung nodules, mediastinal lymphadenopathy, and a history of uterine cancer who underwent endobronchial ultrasound-guided fine needle aspiration and biopsy of the lung and mediastinal lymph nodes. A sampling of the lung lesion showed a cytologically bland neoplasm with spindle cell morphology, lacking necrosis or brisk mitotic activity. In conjunction with the cytomorphology, strong and diffuse Transducin-like enhancer of split 1 (TLE1) reactivity in the tumor cells initially raised the diagnosis of synovial sarcoma; however, subsequent results of additional testing showed strong and diffuse expression with AE1/AE3, CK 8/18, TTF-1, synaptophysin and chromogranin and focal or negative staining with a large number of other antibodies. This warranted a diagnosis of a carcinoid tumor. This is the first report of TLE1 staining in a carcinoid tumor of the lung. Therefore, when evaluating tumors of the lung with spindle cell morphology in which the differential diagnosis may include both carcinoid tumor and synovial sarcoma, TLE1 expression should be interpreted with caution and in conjunction with an expanded immunohistochemical staining panel.

Microsecretory adenocarcinoma of the external ear canal

Microsecretory adenocarcinoma (MSA) is a recently described salivary gland tumor characterized by unique histomorphologic and immunohistochemical features as well as recurrent MEF2C::SS18 gene fusion. Since 2019, 24 cases have been reported in the literature, primarily arising in the oral cavity, with a single reported case arising in the parotid gland. Here, we present a case of MSA that arose in the external ear canal in an 89-year-old woman and was discovered during management of vertigo symptoms. Excisional biopsy of the lesion showed multiple fragments of squamous epithelium with hyperplastic changes and a distinct subepithelial infiltrating neoplasm composed of bland cells forming tubules and cords. Neoplastic cells expressed keratin, S100 protein, p63, and TLE1 and did not express p40, mammaglobin, pan-TRK, synaptophysin, or chromogranin by immunohistochemistry. SS18 gene rearrangement was shown with break-apart fluorescent in situ hybridization. Overall, the histomorphologic, immunohistochemical, and cytogenetic findings confirm a diagnosis of MSA arising in a unique extraoral location.

Roles of transducin-like enhancer of split (TLE) family proteins in tumorigenesis and immune regulation

Mammalian transducin-like enhancer of split family proteins (TLEs) are homologous to Drosophila Groucho (Gro) and are essential transcriptional repressors. Seven TLE family members, TLE1-7, have been identified to date. These proteins do not bind DNA directly; instead, they bind a set of transcription factors and thereby inhibit target gene expression. Loss of TLEs in mice usually leads to defective early development; however, TLE functions in developmentally mature cells are unclear. Recent studies have revealed that TLEs are dysregulated in certain human cancer types and may function as oncogenes or tumor suppressors in different contexts. TLE levels also affect the efficacy of cancer treatments and the development of drug resistance. In addition, TLEs play critical roles in the development and function of immune cells, including macrophages and lymphocytes. In this review, we provide updates on the expression, function, and mechanism of TLEs; discuss the roles played by TLEs in tumorigenesis and the inflammatory response; and elaborate on several TLE-associated signaling pathways, including the Notch, Wnt, and MAPK pathways. Finally, we discuss potential strategies for targeting TLEs in cancer therapy.

miRNAs as Biomarkers and Possible Therapeutic Strategies in Synovial Sarcoma

Synovial sarcoma (SS) is an epithelial-differentiated malignant stromal tumor that has the highest incidence in young people and can occur almost anywhere in the body. Many noncoding RNAs are involved in the occurrence, development, or pathogenesis of SS. In particular, the role of MicroRNAs (miRNAs) in SS is receiving increasing attention. MiRNA is a noncoding RNA abundant in cells and extracellular serums. Increasing evidence suggests that miRNA has played a significant role in the incidence and development of tumors in recent years, including sarcomas. Previous studies show that various sarcomas have their unique miRNA expression patterns and that various miRNA expression profiles can illustrate the classes of miRNAs that may elicit cancer-relevant activities in specific sarcoma subtypes. Furthermore, SS has been reported to have the most number of differentially expressed miRNAs, which indicated that miRNA is linked to SS. In fact, according to many publications, miRNAs have been shown to have a role in the development and appearance of SS in recent years, according to many publications. Since many studies showing that various miRNAs have a role in the development and appearance of SS in recent years have not been systematically summarized, we summarize the recent studies on the relationship between miRNA and SS in this review. For example, miR-494 promotes the development of SS via modulating cytokine gene expression. The role of miR-494-3p as a tumor suppressor is most likely linked to the CXCR4 (C-X-C chemokine receptor 4) regulator, although the exact mechanism is unknown. Our review aims to reveal in detail the potential biological value and clinical significance of miRNAs for SS and the potential clinical value brought by the association between SS and miRNAs.

Clinicopathologic features of a patient with primary monophasic synovial sarcoma of the jejunum

A case of primary synovial sarcoma of the jejunum was collected and analyzed retrospectively. A 19-year-old man who presented to hospital with abdominal pain. The CT scan showed a large mixed abdominal mass with bleeding. Laparotomy revealed that the tumor originated from the jejunum, accompanied by rupture and hemorrhage. Microscopically, the tumor was composed of spindle cells. The tumor cells demonstrated diffuse expression of vimentin, transducin-like enhancer (TLE)-1, B-cell lymphoma protein (Bcl)-2, CD99 and focal expression of epithelial membrane antigen (EMA). The presence of specific SS18 gene rearrangement was confirmed in tumor cells. The patient received 6 cycles of chemotherapy after jejunal tumor resection. And 12 months later, the patient presented pancreatic metastasis and had radiotherapy. The patient died 15 months after the diagnosis.

Diagnosis of soft tissue tumors using immunohistochemistry as a surrogate for recurrent fusion oncoproteins

Soft tissue neoplasms encompass a broad spectrum of clinicopathologic manifestations. In a subset of soft tissue tumors, spanning a wide range of clinical behavior from indolent to highly aggressive, recurrent genetic translocations yield oncogenic fusion proteins that drive neoplastic growth. Beyond functioning as primary mechanisms of tumorigenesis, recurrent translocations represent key diagnostic features insofar as the presence of a particular oncogenic gene fusion generally points to specific tumor entities. In addition to more direct methods for identifying recurrent translocations, such as conventional cytogenetics or fluorescence in situ hybridization, immunohistochemistry for a component of the fusion oncoprotein increasingly is being used as a surrogate marker, exploiting the tendency of these fusion components to be distinctively overexpressed by translocation-bearing tumor cells. Diagnostic immunohistochemistry can also be used to identify the characteristic gene expression changes that occur downstream of oncogenic fusions. Here, we review the use of immunohistochemistry to detect surrogate markers of recurrent translocations in soft tissue tumors, focusing on the practical applications and limitations of this diagnostic approach.

Diagnostic Utility of TLE1 (Transducer-Like Enhancer of Split 1) in Distinguishing Synovial Sarcoma from Mimicking Tumors

Background

Synovial sarcoma (SS) is a high-grade spindle cell tumor that accounts for 5% to 10% of soft tissue sarcomas. The majority originate from the deep intramuscular soft tissues of extremities with common sites including knee, ankle and feet. Immunohistochemical (IHC) stain TLE1 (transducer-like enhancer of split 1) is a potent diagnostic marker for distinguishing SS from mimicking tumors.

Methodology

The study was performed on 177 tumor cases, including 89 SS and 88 non-synovial sarcoma (N-SS) cases which were diagnosed at Department of Pathology and Laboratory Medicine, Aga Khan University Hospital, from July 2019 to June 2020. Hematoxylin and eosin (H&E) and IHC stained glass slides of these cases were reviewed. TLE1 expression was assessed based on the Remmele scoring system.

Results

Eighty-nine cases of SS and 88 cases of N-SS were included in the study. SS cases included 42 (47.2%) monophasic subtype, 6 (6.7%) biphasic subtype and 41 (46.1%) poorly differentiated subtype. Major tumor types in N-SS cases were 27 (30.7%) Ewing sarcoma (ES), 13 (14.8%) leiomyosarcoma, 10 (11.4%) undifferentiated sarcoma (US), 8 (9.1%) fibrosarcomatous dermatofibrosarcoma protuberans and 7 (8%) malignant peripheral nerve sheath tumor cases. Mean patients’ age for SS cases was 26.14 years and for N-SS cases was 32.64 years. All 89 SS cases showed positive TLE1 expression. Out of 88 N-SS cases, 71 (80.7%) were TLE1 negative and 17 (19.3%) showed positive expression.

Conclusion

This study shows that TLE1 is a very sensitive and relatively specific IHC marker for SS. TLE1 expression can be observed in other soft tissue sarcomas but diffuse strong TLE1 expression is highly specific for SS. The diagnosis should not solely rely on TLE1 expression and morphologic features but should include soft tissue specific lineage markers to avoid misdiagnosis.

Primary Intraosseous Synovial Sarcoma in the Mandible

Synovial sarcoma (SS) is a rare malignant mesenchymal tumor that mainly occurs in body extremities, being uncommon in the head and neck region. In the present study, we described a case of primary intraosseous SS arising in the mandible of a 22-year-old young male. The patient reported a painful swelling on the left side of the mandible for the last 7 months. Imaging exams showed the presence of an expansive and multilocular radiolucent lesion, extending from the left condyle to the mandibular body. The clinic diagnostic hypotheses were ameloblastoma or malignant neoplasm. Histologically, the lesion was characterized by a proliferation of spindle cells exhibiting vesicular nuclei and evident nucleolus. Neoplastic cells were positive for AE1/AE3, cytokeratin 7, vimentin, CD-99, and TLE-1 and negative for CD-34, S-100, SMA, and HHF-35. A combination of clinical, histologic, and immunohistochemical characteristics supported the diagnosis of SS. The patient was referred for treatment, and preoperative exams did not reveal any other tumor foci in the body of the patient. The final diagnosis was of a primary intraosseous SS of the mandible.

The Biology of Synovial Sarcoma: State-of-the-Art and Future Perspectives

New molecular insights are being achieved in synovial sarcoma (SS) that can provide new potential diagnostic and prognostic markers as well as therapeutic targets. In particular, the advancement of research on epigenomics and gene regulation is promising. The concrete hypothesis that the pathogenesis of SS might mainly depend on the disruption of the balance of the complex interaction between epigenomic regulatory complexes and the consequences on gene expression opens interesting new perspectives. The standard of care for primary SS is wide surgical resection combined with radiation in selected cases. The role of chemotherapy is still under refinement and can be considered in patients at high risk of metastasis or in those with advanced disease. Cytotoxic chemotherapy (anthracyclines, ifosfamide, trabectedin, and pazopanib) is the treatment of choice, despite several possible side effects. Many possible drug-able targets have been identified. However, the impact of these strategies in improving SS outcome is still limited, thus making current and future research strongly needed to improve the survival of patients with SS.

BCL7B is a potential novel diagnosis and prognosis biomarker for sarcomas using bioinformatics analysis

BCL7B plays a potential role in the progression of various cancers, while its role in sarcomas is unknown. We aimed to evaluate BCL7B's diagnostic and prognostic value, and potential BCL7B-related mechanisms in sarcomas based on The Cancer Genome Atlas (TCGA) database. We collected patients with sarcoma from TCGA. Wilcoxon rank sum test was used to compare the expression of BCL7B in sarcoma samples with different clinical-pathologic features. Univariate Cox regression analysis and multivariate Cox regression analysis were used to evaluate prognosis factors for sarcoma. Gene set enrichment analysis (GSEA) was conducted to elucidate the significant functions and pathways associated with BCL7B. BCL7B was a potential biomarker for distinguishing normal and tumor tissues with the analysis of ROC curve (AUC = 0.588). Low BCL7B expression was significantly correlated with tumor multifocal (OR = 0.39 for yes vs no), larger residual tumor (OR = 0.40 for R1,R2 vs RO), male gender (OR = 0.48 for male vs female) and White race (OR = 0.29 for White vs Asian, Black or African American). High BCL7B expression was correlated with leiomyosarcoma histological type (OR = 6.08 for leiomyosarcoma vs dedifferentiated liposarcoma, pleomorphic sarcoma). Univariate and multivariate Cox regression analysis showed that low BCL7B expression was independently associated with poor overall survival (P = .008). GSEA showed that GPCR (G protein-coupled receptors) ligand binding, secreted factors, class A1 rhodopsin-like receptors, extracellular matrix organization, core matrisome, Fc epsilon receptor I mediated NF-κB activation, and WNT signaling pathway were differentially enriched in BCL7B low expression phenotype (|NES| > 1, adjusted P value <.05, and FDR value <0.25). BCL7B may play an important role in sarcoma progression and may be a potential biomarker for prognosis and diagnosis in sarcomas.

Synovial sarcoma of the transverse colon metastatic to the chest wall after 3 years of follow-up

We report a fifth case of a transverse colon primary synovial sarcoma. A 31-year-old man with history of grade I obesity presented to an outpatient clinic reporting 6 months of intermittent colicky abdominal pain associated with haematochezia and rectal bleeding. Colonoscopy reported a partially obstructive intraluminal tumour lesion located in the transverse colon. There was no evidence of metastatic disease in the extension studies, so the patient was admitted to the hospital for a laparoscopic subtotal colectomy. Histopathology demonstrated intermediate-grade synovial sarcoma. At the third year of follow-up, the patient presented metastases on the chest wall, which required extensive resection and complementary oncological management.

ETV4 and ETV5 drive synovial sarcoma through cell cycle and DUX4 embryonic pathway control

Synovial sarcoma is an aggressive malignancy with no effective treatments for patients with metastasis. The synovial sarcoma fusion SS18-SSX, which recruits the SWI/SNF-BAF chromatin remodeling and polycomb repressive complexes, results in epigenetic activation of FGF receptor (FGFR) signaling. In genetic FGFR-knockout models, culture, and xenograft synovial sarcoma models treated with the FGFR inhibitor BGJ398, we show that FGFR1, FGFR2, and FGFR3 were crucial for tumor growth. Transcriptome analyses of BGJ398-treated cells and histological and expression analyses of mouse and human synovial sarcoma tumors revealed prevalent expression of two ETS factors and FGFR targets, ETV4 and ETV5. We further demonstrate that ETV4 and ETV5 acted as drivers of synovial sarcoma growth, most likely through control of the cell cycle. Upon ETV4 and ETV5 knockdown, we observed a striking upregulation of DUX4 and its transcriptional targets that activate the zygotic genome and drive the atrophy program in facioscapulohumeral dystrophy patients. In addition to demonstrating the importance of inhibiting all three FGFRs, the current findings reveal potential nodes of attack for the cancer with the discovery of ETV4 and ETV5 as appropriate biomarkers and molecular targets, and activation of the embryonic DUX4 pathway as a promising approach to block synovial sarcoma tumors.

Gene of the month: TLE 1

TLE 1 is the human homologue belonging to a family of four genes and is located on chromosome 9q21. It consists of 19 exons. Although it does not bind directly to DNA, it acts as a repressor of several signalling pathways via transcription factors. TLE1 protein has several physiological roles in embryogenesis, haematopoiesis, general differentiation, and both neuronal and eye development. Much attention was focused on its expression in the tumour cell nuclei of synovial sarcoma (SS). However, several other soft tissue tumours that do and do not share morphological similarity with SS also display nuclear immunoreactivity for TLE1; hence, caution in interpretation is advocated.

Loss of histone H3 trimethylation on lysine 27 and nuclear expression of transducin-like enhancer 1 in primary intracranial sarcoma, DICER1-mutant

AIMS

Primary intracranial sarcoma, DICER1-mutant is a recently described central nervous system tumour with specific genomic and DNA-methylation profiles. Although some of its histological features (focal spindle-cell morphology, intracytoplasmic eosinophilic granules, and focal heterologous differentiation) are common across most reported cases, the presence of significant histological variability and the lack of differentiation pose diagnostic challenges. We aim to further define the immunoprofile of this tumor.

METHODS AND RESULTS

We reviewed the clinical history and performed immunohistochemistry for glial fibrillary acidic protein, oligodendrocyte transcription factor 2, SOX2, SOX10, S100, histone H3 trimethylated on lysine 27 (H3K27me3), desmin, myogenin, CD99, epithelial membrane antigen (EMA) and transducin-like enhancer of split 1 (TLE1) on six primary intracranial sarcomas, DICER1-mutant, with appropriate controls. Targeted exome sequencing was performed on all cases. The sarcomas showed diffuse (n = 4), mosaic (n = 1) or minimal (≤5%, n = 1) loss of H3K27 trimethylation and nuclear TLE1 expression (n = 6). Four had immunohistochemical evidence of myogenic differentiation. SOX2, SOX10, S100 and EMA were negative; CD99 expression ranged from focal cytoplasmic (n = 4) to crisp diffuse membranous (n = 2). One tumour had focal cartilaginous differentiation. Similar immunohistochemical findings were observed in a pleuropulmonary blastoma (albeit with focal TLE1 expression), a DICER1-related pineoblastoma, and an embryonal tumour with a multilayered rosette-like DICER1-related cerebellar tumour. Targeted exome sequencing confirmed the presence of pathogenic biallelic DICER1 mutations in all tumours included in this study.

CONCLUSION

We conclude that H3K27me3 and TLE1 immunostains, when utilised in combination, can be helpful diagnostic markers for primary intracranial sarcoma, DICER1-mutant.

Synovial Sarcoma: A Complex Disease with Multifaceted Signaling and Epigenetic Landscapes

PURPOSE OF REVIEW

Aside from a characteristic SS18-SSX translocation identified in almost all cases, no genetic anomalies have been reliably isolated yet to drive the pathogenesis of synovial sarcoma. In the following review, we explore the structural units of wild-type SS18 and SSX, particularly as they relate to the transcriptional alterations and cellular pathway changes imposed by SS18-SSX.

RECENT FINDINGS

Native SS18 and SSX contribute recognizable domains to the SS18-SSX chimeric proteins, which inflict transcriptional and epigenetic changes through selective protein interactions involving the SWI/SNF and Polycomb chromatin remodeling complexes. Multiple oncogenic and developmental pathways become altered, collectively reprogramming the cellular origin of synovial sarcoma and promoting its malignant transformation. Synovial sarcoma is characterized by complex epigenetic and signaling landscapes. Identifying the operational pathways and concomitant genetic changes induced by SS18-SSX fusions could help develop tailored therapeutic strategies to ultimately improve disease control and patient survivorship.