Novel candidate metastasis-associated genes for synovial sarcoma.

Synovial sarcoma (SS) is an aggressive soft tissue sarcoma with poor prognosis due to late recurrence and metastasis. Metastasis is an important prognostic factor of SS. This study aimed to identify the core genes and mechanisms associated with SS metastasis. Microarray data for GSE40021 and GSE40018 were obtained from the Gene Expression Omnibus database. 186 differentially expressed genes (DEGs) were identified. The biological functions and signalling pathways closely associated with SS metastasis included extracellular matrix (ECM) organization and ECM-receptor interaction. Gene set enrichment analysis showed that the terms cell cycle, DNA replication, homologous recombination and mismatch repair were significantly enriched in the metastasis group. Weighted gene co-expression network analysis identified the most relevant module and 133 hub genes, and 31 crossover genes were identified by combining DEGs. Subsequently, four characteristic genes, EXO1, NCAPG, POLQ and UHRF1, were identified as potential biomarkers associated with SS metastasis using the least absolute shrinkage and selection operator algorithm and validation dataset verification analysis. Immunohistochemistry results from our cohort of 49 patients revealed visible differences in the expression of characteristic genes between the non-metastatic and metastatic groups. Survival analysis indicated that high expression of characteristic genes predicted poor prognosis. Our data revealed that primary SS samples from patients who developed metastasis showed activated homologous recombination and mismatch repair compared to samples from patients without metastasis. Furthermore, EXO1, NCAPG, POLQ and UHRF1 were identified as potential candidate metastasis-associated genes. This study provides further research insights and helps explore the mechanisms of SS metastasis.

Synovial Sarcoma of the Gastrointestinal Tract.

We report the clinicopathologic and immunohistochemical features of 18 cases of confirmed primary synovial sarcoma of the gastrointestinal tract. The neoplasms arose in 10 women and 8 men ranging in age from 23 to 81 years (mean: 50; median: 57.5 years). The tumors for which size was known ranged from 1.8 to 15.0 cm (mean: 5.2; median: 5.1 cm). Microscopically, 14 synovial sarcomas were of the monophasic type, 2 were biphasic, and 2 were poorly differentiated. Immunohistochemical analysis of 4 cases showed strong, diffuse staining for SS18::SSX (4/4 cases). Pancytokeratin and EMA immunohistochemistry were performed on 13 and 9 tumors, respectively, and each showed patchy-to-diffuse staining. By reverse-transcription PCR, 3 cases were positive for the SS18::SSX1, and 2 cases were positive for the SS18::SSX2 gene fusion. Six cases contained an SS18 gene rearrangement by fluorescence in situ hybridization, and next-generation sequencing identified an SS18::SSX2 gene fusion in one case. Clinical follow-up information was available for 9 patients (4 months to 4.6 years; mean, 2.8 y; median: 29 months), and one patient had a recent diagnosis. Three patients died of disease within 41 to 72 months (mean, 56 months) of their diagnosis. Five patients were alive without evidence of disease 4 to 52 months (mean, 17.6 months) after surgery; of whom 1 of the patients received additional chemotherapy treatment after surgery because of recurrence of the disease. A single patient was alive with intraabdominal recurrence 13 months after surgery. We conclude that synovial sarcoma of the gastrointestinal tract is an aggressive tumor, similar to its soft tissue counterpart, with adverse patient outcomes. It is important to distinguish it from morphologically similar gastrointestinal tract lesions that may have different treatment regimens and prognoses.

Treatment at relapse for synovial sarcoma of children and adolescents: A multi-institutional European retrospective analysis.

PURPOSE: Though the prognosis for pediatric patients with localised synovial sarcoma (SS) is generally good, the chances of being cured after relapse are limited. This study describes a retrospective multi-institutional series of relapsing SS patients treated at six selected European referral centers for pediatric sarcoma. PATIENTS AND METHODS: The study included 41 patients <21 years with relapsing SS, treated between 2002 and 2022. The analysis included patient's characteristics at first diagnosis, first-line treatments, clinical findings at relapse, and second-line treatment modalities. RESULTS: The first relapse occurred within 3-132 months (median 18 months) after first diagnosis and was local in 34%, metastatic in 54%, and both in 12%. Treatment at first relapse included surgery in 56% of cases, radiotherapy in 34%, and systemic therapy in 88%. In all, 36 patients received second-line medical treatment, that was chemotherapy in 32 cases (with 10 different regimens) and targeted therapy in four. No patient was included in an early-phase clinical trial as second-line therapy-line therapy. Overall response rate was 42%. Median event-free survival (EFS) was 12 months, postrelapse 5-year EFS was 15.8%. Median overall survival (OS) was 30 months, postrelapse 5-year OS was 22.2%. At the Cox's multivariable regression analysis, OS was significantly associated with time and type of relapse. CONCLUSION: Pediatric patients with relapsed SS have a poor prognosis and generally receive an individualized approach, due to the lack of a uniform standardized approach. New comprehensive strategies are needed to improve the knowledge on the biologic landscape of SS and develop tailored prospective clinical trials.

Contemporary surgical management of pediatric non-rhabdomyosarcoma soft tissue sarcoma.

Non-rhabdomyosarcoma soft tissue sarcoma (STS) comprises most STS in pediatric patients. It is a diverse set of over 30 histologic subtypes. Treatment is based on risk group determined by tumor size, grade, and the presence of metastases. Surgical resection is a cornerstone of therapy, as tumors are often resistant to chemotherapy or radiation. While patients with isolated tumors less than 5 cm may undergo upfront resection, strong consideration should be given to neoadjuvant chemoradiotherapy to ensure negative margins at surgical resection and optimal outcomes. Sentinel lymph node biopsy is strongly recommended for clear cell and epithelioid sarcomas. The most common metastatic site is the lung, and metastases should be resected at the end of therapy, when feasible. Unfortunately, many high-risk patients progress on therapy, and alternative strategies including earlier metastatic control require investigation.

Sarcomas of synovial origin in dogs: An updated review.

The purpose of this review is to clarify the terminology, possible cells of origin, and expected behavior of the most common synovial tumors in dogs. The synovial lining consists of 2 cell types, type A and type B. Type A synoviocytes are histiocytes of bone marrow origin that are immunoreactive with antibodies against typical markers of histiocyte origin, such as CD18, Iba-1, and CD204. Certain breeds and dogs with previous injury to a joint, especially cranial cruciate ligament rupture, are predisposed to synovial histiocytic sarcoma. Type B synoviocytes are mesenchymal cells that produce synovial fluid. There are no specific markers of type B synoviocytes, but based on their gross and microscopic appearance, synovial myxosarcomas (previously considered synovial myxomas) are presumed to be of type B synoviocyte origin. These can infiltrate into surrounding tissues, but are slow-growing and rarely metastasize, and then only to regional lymph nodes. Synovial histiocytic sarcomas and myxosarcomas can cause lysis in multiple bones surrounding the joint, but they have different prognoses and require histopathology and sometimes immunohistochemistry to diagnose them. Synovial sarcoma and synovial cell sarcoma are terms used in the human medical literature for a tumor that is not of synovial origin; these terms should not be used in veterinary medicine.

Extensive surgical resections for rare pleural neoplasms: a single-center experience with a yolk sac tumor and synovial sarcoma.

BACKGROUND: Pleural neoplasms are rare and can be subdivided into pleural metastasis and primary pleural neoplasms. Non-mesothelioma primary pleural neoplasms are a diverse group of extremely rare pathologies. CASE PRESENTATION: In this case series, we describe the presentation and management of two rare primary pleural neoplasms. A first case describes a primary pleural yolk sac tumor treated with neoadjuvant chemotherapy, extended pleurectomy decortication, and hyperthermic intrathoracic chemotherapy. In a second case we describe the management of a primary pleural synovial sarcoma by neoadjuvant chemotherapy and extrapleural pneumonectomy. A complete resection was obtained in both cases and the post-operative course was uncomplicated. No signs of tumor recurrence were noted during follow-up in the first patient. In the second patient a local recurrence was diagnosed 6 months after surgery. CONCLUSION: Neo-adjuvant chemotherapy followed by extensive thoracic surgery, including hyperthermic intrathoracic chemotherapy, is a feasible treatment strategy for non-mesothelioma primary pleural neoplasms, but careful follow-up is required.

Underlying synovial sarcoma undiagnosed for more than 20 years in a patient with regional pain: a case report.

Synovial sarcoma (SS) is a malignant tumor comprising 5-10% of all soft tissue sarcomas. SS has distinct characteristics, such as a predilection for young adults and relatively slow growth compared to other soft tissue sarcomas. Some patients with SS experience long-standing pain at the tumor site before the development of a palpable mass. Herein, we report the case of a 39-year-old woman with SS in the upper arm who presented with pain for > 20 years. The tumor detected on magnetic resonance imaging at 17 years was an SS. To the best of our knowledge, no English-language reports on imaging study-based identification of SS, which was undiagnosed for > 20 years, are known in the literature. This report discusses the imaging features of this latent lesion and the volume-doubling time of this unusual tumor.

Ultrastructural differences between synovial sarcoma and solitary fibrous tumor: comparative study in adult patients from the National Cancer Institute of Mexico.

Synovial sarcoma (SS) and solitary fibrous tumor (SFT) are entities with considerable morphological and immunohistochemical similarities that sometimes show a non-confirmatory profile (TLE1 negative, CD34 and focal or negative STAT6 and lack of specific fusion IHC markers), in which the utility ultrastructure is unknown. A cross-sectional, retrospective, analytical, nonexperimental study was carried out by the Department of Pathology of the National Cancer Institute of Mexico (INCan) e from January 1, 2009 to December 31, 2018. With 17 SFT cases with diffuse or focal CD34 and STAT6 positivity and 18 cases of SS with positive FISH molecular test t(X:18) breakapart were studied by electron microscopy of fresh glutaraldehyde fixed or paraffin-embedded tissue. The ultrastructural findings with a significant difference present in the SS were tandem tight junctions, desmosomes and abundance of dilated rough endoplasmic reticulum (RER) cisternae (p < 0.001, 0.003, and 0.001, respectively); while in the (SFT) the presence of abundant glycogen, basal lamina, long and slender cytoplasmic processes, pinocytic vesicles, hemidesmosomes, and/or dense plaques, collagen skein, and microvilli-like buds (p = 0.028, 0.005, and <0.001 for the last five). We then infer that the five distinctive markers of the SFT are the collagen skeins intermingled with cellular processes in a shape of "squid can," and the pinocytic vesicles as they were not observed in any case of SS. Conversely, tandem junctions were not found in any SFT case. Although the presence of multivesicular buds in the SFT was not significant, it had not been previously described.

An unusual case of retroperitoneal synovial sarcoma with CT, MRI, and F-18 FDG PET/CT findings.

Synovial sarcoma, predominantly found in the extremities, rarely occurs in the retroperitoneum. Tumors can often grow to a considerable size before diagnosis, which warrant the critical importance of early detection to minimize morbidity and mortality. While the final diagnosis relies on pathologic examination, imaging plays a crucial role in early detection.

The Combined Immunohistochemical Expression of GLI1 and BCOR in Synovial Sarcomas for the Identification of Three Risk Groups and Their Prognostic Outcomes: A Study of 52 Patients.

Synovial sarcoma (SS) is a rare soft-tissue tumor characterized by a monomorphic blue spindle cell histology and variable epithelial differentiation. Morphologically, SSs may be confused with other sarcomas. Systemic treatment is more effective for patients with high-risk SSs, patients with advanced disease, and younger patients. However, further studies are required to find new prognostic biomarkers. Herein, we describe the morphological, molecular, and clinical findings, using a wide immunohistochemical panel, of a series of SS cases. We studied 52 cases confirmed as SSs by morphological diagnosis and/or molecular studies. Clinical data (gender, age, tumor size, tumor location, resection margins, adjuvant treatment, recurrences, metastasis, and survival) were also retrieved for each patient. All the available H&E slides were examined by four pathologists. Three tissue microarrays (TMAs) were constructed for each of the tumors, and a wide immunohistochemical panel was performed. For time-to-event variables, survival analysis was performed using Kaplan-Meier curves and log-rank testing, or Cox regression. Statistical significance was considered at p < 0.05. The mean age of our patients was 40.33, and the median was 40.5 years. We found a predominance of males versus females (1.7:1). The most frequent morphological subtype was monophasic. TRPS1, SS18-SSX, and SSX-C-terminus were positive in 96% of cases. GLI1 expression was strong in six and focal (cytoplasmic) in twenty patients. Moreover, BCOR was expressed in more than half of SSs. Positive expression of both proteins, BCOR and GLI1, was correlated with a worse prognosis. Multivariate analysis was also performed, but only BCOR expression appeared to be significant. The combination of GLI1 and BCOR antibodies can be used to group SSs into three risk groups (low, intermediate, and high risk). We hypothesize that these findings could identify which patients would benefit from receiving adjuvant treatment and which would not. Moreover, these markers could represent therapeutic targets in advanced stages. However, further, larger series of SSs and molecular studies are necessary to corroborate our present findings.

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.

POU2AF3-rearranged sarcomas: A novel tumor defined by fusions of EWSR1 or FUS to a gene formerly designated COLCA2.

Gene fusions involving EWSR1 or FUS as the 5' partner have been reported in a diverse array of sarcomas. Here, we characterize the histopathology and genomics of six tumors harboring a gene fusion between EWSR1 or FUS and POU2AF3, an understudied, putative colorectal cancer predisposition gene. Striking morphologic features reminiscent of synovial sarcoma were observed including a biphasic appearance with variable fusiform to epithelioid cytomorphology and staghorn-type vasculature. RNA sequencing demonstrated variable breakpoints in EWSR1/FUS along with similar breakpoints in POU2AF3 that encompassed a 3' portion of this gene. For cases in which additional information was available, the behavior of these neoplasms was aggressive with local spread and/or distant metastases. Although further studies are needed to confirm the functional significance of our findings, POU2AF3 fusions to EWSR1 or FUS may define a novel type of POU2AF3-rearranged sarcomas with aggressive, malignant behavior.

[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.

A phase II study of gemcitabine and docetaxel combination in relapsed metastatic or unresectable locally advanced synovial sarcoma.

Synovial sarcoma (SS) is one of the commonest non-rhabdomyosarcoma soft tissue sarcoma with limited treatment options in the relapsed and advanced settings. The combination of gemcitabine and docetaxel has demonstrated its role predominantly in leiomyosarcoma and pleomorphic sarcomas but has not been prospectively studied in SS. This trial assesses the efficacy, tolerability and quality of life (QoL) with this regimen in metastatic/unresectable locally advanced relapsed SS.Patients and methods This was a single-arm, two-stage, phase II, investigator-initiated interventional study among patients with metastatic or unresectable locally advanced SS who had progressed after at least one line of chemotherapy. Gemcitabine 900 mg/m2 on days 1 and 8 and docetaxel 75 mg/m2 on day 8 were administered intravenously every 21 days. The primary endpoint was 3-month progression-free rate (PFR); overall survival (OS), progression-free survival (PFS), overall response rate (ORR), safety and quality of life (QoL) constituted the secondary endpoints.Results Twenty-two patients were enrolled between March 2020 and September 2021 and the study had to be closed early due to slow accrual. The study population comprised of 18 (81.8%) patients with metastatic disease and 4 (18.2%) patients with locally advanced, unresectable disease. The most common primary sites of disease were extremity in 15 (68%) and the median number of lines of prior therapies received was 1 (range 1-4). 3-month PFR was 45.4% (95% CI 24.8-66.1) and ORR was 4.5%. Median progression-free survival (PFS) was 3 months (95% CI 2.3-3.6) and median OS was 14 months (95% CI 8.9-19.0). 7 (31.8%) patients experienced grade 3 or worse toxicities, including anemia (18%), neutropenia (9%) and mucositis (9%). QoL analysis demonstrated significant decline in certain functional and symptom scales, while financial and global health scales remained stable.Conclusion This is the first prospective study on the combination of gemcitabine and docetaxel performed specifically in patients with advanced, relapsed SS. Although the accrual of patients could not be completed as planned, the therapy did produce clinically meaningful outcomes and met its primary endpoint of 3-month PFR. This result, along with the manageable toxicity profile and stable global health status on QoL analysis, should encourage further studies.Trial registration This trial was prospectively registered under the Clinical Trials Registry of India on 26/02/2020 (Registration number: CTRI/2020/02/023612).

Optimal timing of re-excision in synovial sarcoma patients: Immediate intervention versus waiting for local recurrence.

BACKGROUND: To investigate the difference in efficacy of re-excision in synovial sarcoma patients with and without residual tumor following unplanned excision, and to compare the prognostic outcomes of immediate re-excision versus waiting for local recurrence. METHOD: This study included synovial sarcoma patients who underwent re-excision at our center between 2009 and 2019, categorized into groups based on unplanned excision and local recurrence. Analyzed endpoints included overall survival (OS), local recurrence-free survival (LRFS), and distant relapse-free survival (DRFS). Prognostic factors associated with these three different survival outcomes were analyzed through the use of Kaplan-Meier curves and Cox regression approaches. RESULT: In total, this study incorporated 109 synovial sarcoma patients, including 32 (29.4%) with no residual tumor tissue identified after re-excision, 31 (28.4%) with residual tumor tissue after re-excision, and 46 (42.2%) with local recurrence after initial excision. Patients were assessed over a median 52-month follow-up period. The respective 5-year OS, 5-year LRFS, and 5-year DRFS rates were 82.4%, 76.7%, and 74.2% for the nonresidual group, 80.6%, 80.4%, and 77.3% for the residual tumor tissue group, and 63.5%, 50.7%, and 46.3% for the local recurrence group. There was no significant difference in OS of nonresidual group and residual group patients after re-excision (p = 0.471). Concurrent or sequential treatment with chemotherapy and radiotherapy significantly reduced the risk of metastasis and mortality when compared with noncombined chemoradiotherapy, and was more effective in the local recurrence group (p < 0.05). CONCLUSION: Prompt and adequate re-excision is crucial for patients with synovial sarcoma who undergo initial inadequate tumor excision, and their prognosis is significantly better compared with patients who delay re-excision until local recurrence.

Synovial sarcoma of the tibial nerve - case report of a rare tumor in a rare location requiring early diagnosis.

BACKGROUND: We present the case of a patient with a rare synovial sarcoma (SS) of the tibial nerve. So far, only 4 cases of patients with SS originating from the tibial nerve have been described in the literature, and our patient is only the second patient whose limb was saved during treatment. Synovial sarcomas are malignant mesenchymal tumors, i.e., tumors arising from connective tissue. Synovial sarcomas account for 5-10% of all soft tissue sarcomas. However, the name synovial sarcoma is misleading, because the tumor does not originate from synovial cells, but rather from primitive mesenchymal cells. The name most likely originated from the localization around the large joints on the limbs, more often on the lower ones, in the area of the knee joints. We point out the aspects of correct and quick diagnosis and subsequent treatment, which has very important effect on the patient's prognosis. Primary less radical excision without prior biopsy verification leads to a higher risk of local recurrence, even if a proper reexcision was performed immediately after biopsy verification of the sarcoma. CASE PRESENTATION: A woman born in 1949 began to suffer at the end of 2020 with escalating pain under the left inner ankle with a projection to the sole and fingers. Her personal, family work and social history were insignificant. After the initial neurological examination, the patient was sent for an ultrasound examination of the ankle, which showed a lobular mass measuring 50 × 22 × 16 mm and according magnetic resonance imaging, the finding appeared to be a suspicious neurinoma of the tibial nerve. The tumor was surgically excised, without prior biopsy verification: a 50 × 20 mm tumor was dissected in the distal part of the tarsal canal, which grew through the structure of the tibial nerve and in some places into the surrounding area and appeared intraoperatively as a neurofibroma. But histologically the tumor was classified as monophasic synovial sarcoma. The patient was indicated for a wide reexcision of the skin with the subcutaneous tissue of size 91 × 20 × 15 mm. Now the patient is being treated with external radiotherapy to the tumor bed and she is able to walk. CONCLUSION: This report draws attention to a rare type of malignant nerve tumor, which both clinically and radiologically can mimic benign peripheral nerve sheath tumors. Synovial sarcoma should be considered in very painful resistances, typically located around the joints of the lower limbs, the growth of which can be slow. Because the size of the tumor is a negative prognostic factor, it is necessary to make a timely diagnosis using MR imaging and a biopsy with histological examination and to start treatment quickly. Surgical treatment should take place only after a biopsy with histological examination of the tumor so that it is sufficiently radical and does not have to undergo an additional reoperation, as happened in the case of our patient.

Synovial sarcoma with intra-abdominal metastasis causing hemoperitoneum: a case-report.

Synovial sarcoma is a rare soft tissue sarcoma which frequently involves the upper or lower extremities. Soft tissue sarcomas including synovial sarcoma have a propensity to metastasize to the lungs, and there are very few reports of metastatic lesions in other locations.Here, we report a case of a 49-year-old patient who underwent neoadjuvant chemoradiation for an upper extremity synovial sarcoma and presented approximately 4 years later with abdominal pain and hemoperitoneum and was ultimately found to have metastatic synovial sarcoma involving the greater curvature of the stomach and surrounding peri-gastric soft tissue. We describe the multidisciplinary management of this complex patient presentation and propose that expanded surveillance imaging beyond that of the local tumor resection bed and the chest may be beneficial especially in tumors with high-risk features.

Perspectives of Cell Sensitivity/Resistance Assay in Soft Tissue Sarcomas Chemotherapy.

Treatment of highly malignant soft tissue sarcomas (STSs) requires multicomponent therapy including surgery, radiotherapy, and chemotherapy. Despite the advancements in targeted cancer therapies, cytostatic drug combinations remain the gold standard for STS chemotherapy. The lack of algorithms for personalized selection of STS chemotherapy leads to unhelpful treatment of chemoresistant tumors, causing severe side effects in patients. The goal of our study is to assess the applicability of in vitro chemosensitivity/resistance assays (CSRAs) in predicting STS chemoresistance. Primary cell cultures were obtained from 148 surgery samples using enzymatic and mechanical disaggregation. CSRA was performed using resazurin-based metabolic activity measurement in cells cultured with doxorubicin, ifosfamide, their combination and docetaxel, gemcitabine, and also their combination for 7 days. Both the clinical data of patients and the CSRA results demonstrated a higher resistance of some cancer histotypes to specific drugs and their combinations. The correlation between the CSRA results for doxorubicin and ifosfamide and clinical responses to the combination chemotherapy with these drugs was demonstrated via Spearman rank order correlation. Statistically significant differences in recurrence-free survival were also shown for the groups of patients formed, according to the CSRA results. Thus, CSRAs may help both practicing physicians to avoid harmful and useless treatment, and researchers to study new resistance markers and to develop new STS drugs.

Synovial sarcoma: a rare neoplasm of paranasal sinus.

Synovial Sarcoma (SS) is a rare soft-tissue malignant tumour. Its presentation in the head and neck region is uncommon. Because of the complex anatomy of the head and neck region, surgery with clear margins is not achievable. In such cases, a multi-modality approach is required as there is no established standard of care. In this report, we share the case of a girl who presented with nasal obstruction. Imaging revealed a mass involving the left nasal cavity, paranasal sinuses without intracranial extension. It was diagnosed as synovial sarcoma. She underwent surgical excision and adjuvant radiation therapy (RT) to the tumour bed, followed by an incomplete course of chemotherapy. Later on, she developed systemic disease. Considering the rarity of this case and lack of guidelines for standard treatment, we report on this case to share our experience with management and treatment outcome.

Case Report of Primary Synovial Sarcoma of the Thyroid Gland: An Unusual Histology at Atypical Location.

Primary synovial sarcoma of the thyroid gland is extremely rare, aggressive, and has a dismal prognosis. We report the case of a 15-year-old male who presented with a progressively increasing neck mass, which was excised and the histopathological and immunohistochemical study suggested biphasic synovial sarcoma of the thyroid gland which was confirmed by synovial sarcoma translocation. There are 14 cases of primary synovial sarcoma of the thyroid reported in the literature so far. This study aimed to document the occurrence of synovial sarcoma histology at an unusual anatomical location with a review of the literature on this rare entity.