Poorly differentiated synovial sarcoma: an analysis of clinical, pathologic, and molecular genetic features

Biphasic synovial sarcoma with myoepithelial features: a distinctive variant with a predilection for the foot

Synovial sarcoma (SS) is a tumor known for its classic monophasic spindle cell or biphasic morphology. However, it exhibits a wide range of histologic variations, leading to diagnostic challenges. Here, we present four cases of molecularly confirmed, biphasic SS originating in the feet and displaying myoepithelial differentiation. The patients were two men and two women with an age range from 19 to 71 years (mean, 45 years). Each tumor showed foci with conventional spindle cell morphology. The epithelial components included areas with nests and cords of epithelioid cells set within a hyalinized and sclerotic stroma. The cytoplasm was clear to pale and eosinophilic. The nuclei were ovoid-round with fine chromatin and small to inconspicuous nucleoli. Mitotic figures were present (2-13 per 10 high-power fields; mean, 6.5). Immunohistochemical studies showed variable staining of the myoepithelial-like regions for low molecular weight keratins, EMA, p63, and S100 protein. Molecular studies confirmed the presence of SS18::SSX1/2 fusion in all four tumors. These cases highlight an unusual variant of synovial sarcoma with an apparent predilection for the distal lower extremity and suggest that differentiation of biphasic synovial sarcoma may be impacted by the anatomic site. Awareness of this variant is important to avoid misclassification and potential treatment and prognostic implications.

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.

Multivariate evaluation of prognostic markers in synovial sarcoma

AIMS

Synovial sarcoma (SS) is an aggressive neoplasm but with varied clinical outcomes despite standard treatment protocols. Several clinicopathological features and immunohistochemical stains have been proposed as prognostic markers in SS. The aim of this study was to evaluate SS from a single institution for prognostically relevant clinicopathological and immunohistochemical factors.

METHODS

We identified a single-institution cohort of SS with follow-up. Clinical and pathological factors examined included age, sex, tumour location, AJCC (American Joint Committee on Cancer) stage, tumour size, grade and status of surgical margins. Immunohistochemical staining for p16, p53, RB1, MYC, PTEN (phosphatase and tensin homologue), β-catenin, MDM2 and Ki67 proliferative index was performed on tissue microarray. Cox proportional hazard model was used for multivariate assessment of overall survival (OS) and disease-free survival (DFS).

RESULTS

133 patients with SS met the inclusion criteria for our cohort, with 100 having complete dataset for all study covariates. On Cox regression multivariate analysis, location (axial vs extremity, p<0.001), AJCC stage (p<0.001), p16 expression (≥75%, p=0.021) were significantly associated with worse OS, whereas PTEN intensity (score 2, p<0.001) and p53 expression (null/≥75%, p=0.013) were correlated with improved OS. For DFS analysis, location (axial vs extremity, p=0.030), tumour size (≥5 cm, p=0.009) and MYC expression (≥33%, p=0.013) were associated with inferior outcome. Only PTEN intensity (score 2, p<0.001) correlated with improved DFS.

CONCLUSIONS

In reviewing numerous clinicopathological and immunohistochemical markers, this study shows that location, AJCC stage, p16, p53 and PTEN expression were prognostically significant in multivariate analysis for OS in a uniformly treated SS cohort. Location, tumour size, MYC and PTEN expression were significantly associated with DFS.

A Practical Approach to Small Round Cell Tumors Involving the Gastrointestinal Tract and Abdomen

Small round cell neoplasms are diagnostically challenging owing to their clinical and pathologic overlap, necessitating use of large immunopanels and molecular analysis. Ewing sarcomas (ES) are the most common, but EWSR1 is translocated in several diverse neoplasms, some with round cell morphology. Molecular advances enable classification of many tumors previously termed 'atypical ES'. The current WHO Classification includes two new undifferentiated round cell sarcomas (with CIC or BCOR alterations), and a group of sarcomas in which EWSR1 partners with non-Ewing family transcription factor genes. This article reviews the spectrum of small round cell sarcomas within the gastrointestinal tract and abdomen.

Synovial sarcoma: cytopathology of 51 cases highlighting the application of ancillary molecular testing

INTRODUCTION

Among sarcomas, synovial sarcoma (SS) is defined by its unique SS18 cytogenetic translocation. Fine needle aspiration (FNA) biopsy is in a key position to exploit this uniqueness for diagnostic purposes.

MATERIALS AND METHODS

Our cytopathology files were searched for examples of SS with histopathologic verification. FNA biopsy, imprint smears, and core needle biopsy (CNB) were performed using standard techniques.

RESULTS

Fifty-one cases from 49 patients (male/female ratio, 1:1; age range, 12-79 years; mean age, 40 years) met the inclusion criteria. Of the 51 cases, 44 (86%) were FNAs, 6 were cytology imprints, and 1 was pleural fluid. Eleven aspirates had concurrent CNB. All cases had tissue confirmation. The biopsy sites included extremities (n = 24; 47%), trunk (n = 12; 24%), lung (n = 8; 16%), head or neck (n = 6; 12%), and pleural fluid (n = 1; 2%). The aspirates were from primary (n = 36; 71%), metastatic (n = 12; 24%), and recurrent (n = 3; 5%) neoplasms. The cytologic diagnoses were SS (69%), suspicious for SS (12%), malignancy (10%), spindle cell neoplasm (4%), and malignancy other than SS (6%). In general, smears and imprints contained dense cell aggregates and single cells composed of a monotonous population having fusiform, rounded, or ovoid banal nuclei and scant cytoplasm. Poorly differentiated SS showed both large epithelioid cell and small cell cytomorphology. When performed, SS18 immunohistochemical and genetic testing was positive in all 19 FNA and 3 CNB cases.

CONCLUSIONS

When coupled with appropriate ancillary testing, FNA biopsy allows for a specific, accurate diagnosis of SS in most cases.

Frequent TRPS1 expression in synovial sarcoma is associated with SS18-SSX fusion oncoprotein activity

Synovial sarcoma is an aggressive translocation-associated soft tissue tumor driven by an SS18-SSX fusion oncoprotein. TRPS1 is a recently identified marker for breast carcinoma, but less is known about its expression in other tumor types. We encountered a case of synovial sarcoma showing strong and diffuse expression of TRPS1. To better characterize this observation, we examined the immunohistochemical expression of TRPS1 in 165 cases of synovial sarcoma, including 70 primary, 21 recurrent, and 74 metastatic tumors, using tissue microarrays. TRPS1 expression was observed in 86% of cases. Among the positive cases, TRPS1 labeled >50% of tumor cells in 57% of cases, and staining intensity was strong or moderate in 68%. Metastatic tumors more frequently demonstrated strong and diffuse TRPS1 expression compared to primary tumors. To understand the mechanism of TRPS1 expression, we interrogated publicly available gene expression and ChIP-seq datasets and found that TRPS1 transcript levels are increased in synovial sarcoma compared to other soft tissue sarcomas. Data from ChIP-seq experiments showed enrichment of SS18-SSX protein at the TRPS1 locus and co-localization with RNA pol II. The TRPS1 locus is also enriched in several histone modifications associated with active transcription. In functional knockdown data, repression of SS18::SSX in synovial sarcoma cell lines is associated with reduced TRPS1 transcript levels, further supporting a model whereby TRPS1 expression is mediated, at least in part, by the SS18-SSX fusion oncoprotein. Knowledge of TRPS1 expression in synovial sarcoma may help avoid potential diagnostic pitfalls in the immunohistochemical workup of tumors.

Biphasic synovial sarcoma with a striking morphological divergence from the main mass to lymph node metastasis: A case report

RATIONALE

Synovial sarcoma accounts for 5% to 10% of all soft tissue sarcomas and involves almost any anatomic site, particularly the deep soft tissue of the extremities of young adults. The incidence rate of lymph node metastases in synovial sarcoma is 3% to 7%, but the detailed morphological features of the metastatic tumors in the lymph node have not been documented.

PATIENT CONCERNS

A 64-year-old Korean man presented with a huge mass in the left lower thorax and multiple hypermetabolic lymph nodes along the mediastinal, supraclavicular, internal mammary, and retrocrural regions.

DIAGNOSES

The patient was diagnosed with primary pleuropulmonary biphasic synovial sarcoma with lymph node metastases, where the main mass mostly comprised spindle cells (>95%) and the metastatic lymph nodes comprised only epithelial cells.

INTERVENTIONS

Left lower lobe lobectomy with the resection of the chest wall (including left ribs 8-10) and diaphragm and mediastinal lymph node dissection were performed.

OUTCOMES

In the 2-month follow-up period, there have been no complications so far, and the attending physician is currently planning for the adjuvant chemotherapy.

LESSONS

The main mass and the metastatic lesion can be clearly different morphologically. In tumors with biphasic differentiation, such as synovial sarcoma, cells that constitute only a small fraction of the main mass may appear as the dominant cells in metastatic lesions.

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.

Mesenchymal Tumors of the Mediastinum: An Update on Diagnostic Approach

Mesenchymal tumors of the mediastinum are a heterogenous group of rare tumors with divergent lineages. Mediastinal mesenchymal tumors are diagnostically challenging due to their diversity and morphologic overlap with nonmesenchymal lesions arising in the mediastinum. Accurate histologic diagnosis is critical for appropriate patient management and prognostication. Many mediastinal mesenchymal tumors affect distinct age groups or occur at specific mediastinal compartments. Neurogenic tumors, liposarcoma, solitary fibrous tumor, and synovial sarcoma are common mesenchymal tumors in the mediastinum. Herein, we provide an update on the diagnostic approach to mediastinal mesenchymal tumors and a review of the histologic features and differential diagnosis of common benign and malignant mesenchymal tumors of the mediastinum.

Cytological features of BCOR-CCNB3 sarcoma: Comparison with Ewing sarcoma and synovial sarcoma

INTRODUCTION

BCOR-CCNB3 sarcoma (BCS) is one of the histological types classified as an undifferentiated small round cell sarcoma of bone and soft tissue. This sarcoma frequently develops in males under 20 years of age. Histologically, a delicate capillary network has been reported as a conspicuous finding. In this study, the cytological findings of BCS were observed in two cases of primary lesions and one case of a lung metastatic lesion. The cytological findings of BCS were compared with its histological mimics, and the characteristic findings of BCS were examined.

METHODS

Three cases of BCS were studied, and a cytological comparison was performed with 8 cases of Ewing sarcoma (ES) and 10 cases of synovial sarcoma (SS; monophasic type: 7 cases, biphasic type: 2 cases, poorly differentiated: 1 case).

RESULTS

In all BCS cases, small clusters with thin and delicate vascular cores and tiny vascular fragments were conspicuous. In ES and SS cases, although small clusters with vascular cores were observed, the vascular cores were thicker than in BCS, and no tiny vascular fragments appeared in most cases. Cytomorphological differences of tumour cells were also observed among BCS, ES, and SS. Predominantly rounded nuclei with fine chromatin and inconspicuous nucleoli can be cytological clues for BCS.

CONCLUSIONS

BCS shows characteristic cytological findings that make the diagnosis of BCS more likely than that of ES and SS. Cytological evaluation is a useful tool for appropriate differential diagnosis that leads to a more accurate final diagnosis and rapid treatment.

Synovial Sarcoma: A Clinical Review

Synovial sarcomas (SS) represent a unique subset of soft tissue sarcomas (STS) and account for 5–10% of all STS. Synovial sarcoma differs from other STS by the relatively young age at diagnosis and clinical presentation. Synovial sarcomas have unique genomic characteristics and are driven by a pathognomonic t(X;18) chromosomal translocation and subsequent formation of the SS18:SSX fusion oncogenes. Similar to other STS, diagnosis can be obtained from a combination of history, physical examination, magnetic resonance imaging, biopsy and subsequent pathology, immunohistochemistry and molecular analysis. Increasing size, age and tumor grade have been demonstrated to be negative predictive factors for both local disease recurrence and metastasis. Wide surgical excision remains the standard of care for definitive treatment with adjuvant radiation utilized for larger and deeper lesions. There remains controversy surrounding the role of chemotherapy in the treatment of SS and there appears to be survival benefit in certain populations. As the understanding of the molecular and immunologic characteristics of SS evolve, several potential systematic therapies have been proposed.

Synovial Sarcoma of the Female Genital Tract: A Protean Mimic of Müllerian Neoplasia

Synovial sarcoma most commonly occurs in the extremities but has rarely been described in the female genital tract. In this series, we describe the clinical, morphologic, immunohistochemical, and molecular features of 7 cases of vulvovaginal synovial sarcoma (vulva, n=6; vagina, n=1). We emphasize their wide morphologic spectrum, which can overlap significantly with other more common tumors at these sites, as highlighted by 2 cases initially diagnosed as other entities (endometrioid carcinoma and malignant peripheral nerve sheath tumor). The average patient age was 41 (range: 23 to 62) years and tumor size ranged from 0.8 to 7 cm. Histologically, the tumors were biphasic (n=6) and monophasic (n=1). All cases were confirmed with fluorescence in situ hybridization or sequencing, and 5/5 cases were positive for the novel immunohistochemical markers SSX and SS18-SSX. In 3 cases with follow-up, 2 patients died of disease and 1 was alive with no evidence of disease. Previously described cases arising in the female genital tract are also reviewed. Vulvovaginal monophasic synovial sarcoma raises a broad differential diagnosis, including smooth muscle tumors, spindled carcinomas, and melanoma. Biphasic synovial sarcoma may mimic Müllerian carcinosarcoma, endometrioid carcinoma with spindled, corded, and hyalinized elements, and mesonephric-like adenocarcinoma. Awareness that synovial sarcoma can occur in the female genital tract with a wide variety of histologic appearances is critical for correctly diagnosing this rare entity. In particular, synovial sarcoma should be considered for any deeply situated "adenocarcinoma" in the vulva, with attention to subtle spindle cell differentiation.

TRPA1 Expression in Synovial Sarcoma May Support Neural Origin

Synovial sarcoma (SS) is a malignant mesenchymal soft tissue neoplasm. Despite its name, the cells of origin are not synovial cells, but rather neural, myogenic, or multipotent mesenchymal stem cells have been proposed as possible cells originators. Unlike other sarcomas, an unusual presentation of long-term pain at the tumor site has been documented, but the exact mechanisms have not been fully clarified yet. The transient receptor potential ankyrin 1 (TRPA1) is a nonselective cation channel mainly expressed in primary sensory neurons, where it functions as a pain sensor. TRPA1 have also been described in multiple non-excitable cells, including those derived from neural crest stem cells such as glial cells and, in particular, Schwann cell oligodendrocytes and astrocytes. We evaluated TRPA1 expression in SS. We selected a cohort of 41 SSs, and by immunohistochemistry, we studied TRPA1 expression. TRPA1 was found in 92.6% of cases. Triple TRPA1/pS100/SOX10 and TRPA1/SLUG/SNAIL staining strongly supports a neural origin of SS. TRPA1 positivity was also observed in a subset of cases negative with pS100, SOX10 and/or SLUG/SNAIL, and these divergent phenotypes may reflect a process of tumor plasticity and dedifferentiation of neural-derived SSs. Given the functional diversity of TRPA1 and its expression in neuronal and non-neuronal multipotent neural crest stem cells, it remains to be determined whether TRPA1 expression in SSs neoplastic cells plays a role in the molecular mechanism associated with premonitory pain symptoms and tumor progression.

Primary superficial synovial sarcoma: clinical and histopathological characteristics in eight cases with molecular confirmation

BACKGROUND AND AIMS

Synovial sarcoma (SS) is a spindled cell sarcoma demonstrating varying degrees of epithelial differentiation and characterized by a pathognomonic t(X;18) translocation. SS most frequently involves deep soft tissue of the extremities in young adults. Superficial SS involving dermis and/or subcutaneous tissue is exceedingly rare.

METHODS AND RESULTS

We identified eight cases of primary superficial synovial sarcomas across three tertiary institutions. All cases were confined to the dermis/subcutis based on imaging or gross and microscopic examination. The average patient age was 36 years (range 14-50). The average tumor size was 2.4 cm (range 0.9-3.9 cm) and lesions showed classic monophasic (n = 4) or biphasic (n = 4) morphology. All tumors expressed keratin AE1/AE3 and/or epithelial membrane antigen (EMA), but were negative for CD34. The diagnosis for each case was confirmed by molecular detection of t(X;18). Six of the eight cases were treated with curative excision while the other two received additional radiotherapy. Follow-up was available for six patients (mean 68 months, range 2-108 months) and no patient experienced recurrence or metastatic disease.

CONCLUSIONS

We present the largest series to date of primary superficial SS with molecular confirmation for all cases. SS should be considered when evaluating a cutaneous monomorphic spindle cell neoplasm.

Retroperitoneal Sarcomas: An Update on the Diagnostic Pathology Approach

Retroperitoneal sarcomas are a heterogenous group of rare tumors arising in the retroperitoneum. Retroperitoneal sarcomas comprise approximately 10% of all soft tissue sarcomas. Though any soft tissue sarcoma histologic types may arise in the retroperitoneal space, liposarcoma (especially well-differentiated and dedifferentiated types) and leiomyosarcoma do so most commonly. Retroperitoneal sarcomas are diagnostically challenging, owing to their diversity and morphological overlap with other tumors arising in the retroperitoneum. An accurate diagnosis is necessary for correct management and prognostication. Herein, we provide an update on the diagnostic approach to retroperitoneal sarcomas and review their key histologic findings and differential diagnoses.

Update on the pathologic diagnosis of malignant mesothelioma

Malignant mesothelioma is an uncommon tumor that may be difficult to diagnose. The International Mesothelioma Interest Group has been writing guidelines for pathological diagnosis that are periodically updated. The guidelines are being updated based on published literature in the last 3 years, and experience of more than 20 leading international pathologists in the field who will be co-authors. Updates were discussed by attendees of the Pulmonary Pathology Society Biennial Meeting (Dubrovnik, Croatia, June 2019). Areas with significant advancements/changes include utilization of immunohistochemistry (establishing mesothelial lineage and benign versus malignant), prognosis and nuclear grading, biphasic malignant mesothelioma, transitional pattern, malignant mesothelioma in situ, and therapeutic/molecular targets.

Synovial Sarcoma of the Nerve-Clinical and Pathological Features: Case Series and Systematic Review

BACKGROUND

Synovial sarcoma of the nerve is a rare entity with several cases and case series reported in the literature. Despite an improved understanding of the biology, the clinical course is difficult to predict.

OBJECTIVE

To compile a series of patients with synovial sarcoma of the peripheral nerve (SSPN) and assess clinical and pathological factors and their contribution to survival and recurrence.

METHODS

Cases from 2 institutions collected in patients undergoing surgical intervention for SSPN. Systematic review including PubMed and Scopus databases were searched for related articles published from 1970 to December 2018. Eligibility criteria: (1) case reports or case series reporting on SSPN, (2) clinical course and/or pathological features of the tumor reported, and (3) articles published in English.

RESULTS

From patients treated at our institutions (13) the average follow-up period was 3.2 yr. Tumor recurrence was seen in 4 cases and death in 3. Systematic review of the literature yielded 44 additional cases with an average follow-up period of 3.6 yr. From pooled data, there were 10 recurrences and 7 deaths (20% and 14%, respectively). Adjuvant treatment used in 62.5% of cases. Immunohistochemical markers used in diagnosis varied widely; the most common are the following: Epithelial membrane antigen (EMA), cytokeratin, vimentin, cluster of differentiation (CD34), and transducin-like enhancer of split 1 (TLE1). Statistical analysis illustrated tumor size and use of chemotherapy to be negative predictors of survival. No other factors, clinically or from pathologist review, were correlated with recurrence or survival.

CONCLUSION

By combining cases from our institution with historical data and performing statistical analysis we show correlation between tumor size and death.

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

BACKGROUND

Synovial sarcoma can present morphologically in multiple forms, including biphasic and monophasic subtypes. As a result, the histological diagnosis can sometimes be challenging. Transducin-Like Enhancer 1 (TLE1) is a transcriptional corepressor that normally is involved in embryogenesis and hematopoiesis but is also expressed in certain tumors. This systematic review examines the potential role of TLE1 as a diagnostic biomarker for the synovial sarcoma. Materials and Methods. A literature review and meta-analysis were conducted using the electronic databases Pubmed, the Cochrane Library, and Google Scholar. Thirteen studies met our eligibility criteria and were selected for in-depth analysis.

RESULTS

The mean sensitivity and specificity of TLE1 in detecting synovial sarcoma were 94% (95% CI 91%-97%) and 81% (95% CI 72%-91%), respectively, when all studies were aggregated together. The mean positive predictive value (PPV) of TLE1 was 75% (95% CI 62%-87%), whereas the negative predictive value (NPV) was 96% (95% CI 93%-98%).

CONCLUSION

TLE1 is a sensitive and specific marker for synovial sarcoma that can aid in its diagnosis. Due to its involvement in several relevant signaling pathways, TLE1 might have direct relevance to the pathophysiology of the disease.

Desmoplastic small round cell tumor showing solid proliferation with limited desmoplasia and confusing immunohistochemical findings: an autopsy report

We herein report a variant case of desmoplastic small round cell tumor (DSRCT) showing limited desmoplasia and confusing immunohistochemical findings. A 26-year-old male was referred for multiple abdominal masses. Laparoscopic biopsy showed only the solid proliferation of small round cells, and he was initially diagnosed with small cell carcinoma. At autopsy, the tumor spread diffusely throughout the abdominal and pelvic cavities. Although the tumor was composed of a predominantly solid pattern of small round cells, multiple samples revealed a fibrous stroma in limited areas only. While immunohistochemistry showed the diffuse expression of desmin, CD99, and bcl-2, epithelial differentiation was unclear with few cytokeratin-positive cells and no staining for the epithelial membrane antigen. Although fluorescence in situ hybridization analysis indicated the EWSR1 gene rearrangement, we were unable to exclude Ewing sarcoma considering the morphological and immunohistochemical findings. The diagnosis of DSRCT was confirmed with a reverse transcription-polymerase chain reaction for EWSR1-WT1 fusion transcripts. DSRCT must be included in a differential diagnosis of small round cell tumors even if desmoplasia is not immediately detected, and thorough sampling and a molecular analysis are mandatory.

A Retrospective Case Series of Synovial Sarcoma of the Upper Extremity

Purpose

Previous studies have grouped the treatment of axial and appendicular synovial sarcomas. The purpose of this study was to assess the prognostic variables of upper extremity synovial sarcomas (UESS) and compare the outcomes of those who underwent a nononcologic or inadvertent excision prior to definitive resection to those who underwent an initial oncologic resection.

Methods

We reviewed the records of 23 UESS treated with definitive surgery at our institution between 1990 and 2014. There were 13 women and 10 men with a median age of 30 years (6–60) and median follow-up of 63 months (15–248). Prognostic variables, recurrence-free survival (RFS), and overall survival (OS) were then assessed.

Results

Fifteen patients (65%) had a prior unplanned excision. Five patients required an amputation to obtain local control of disease. There were 3 observed local recurrences and 2 distant metastases at a median of 45 months from presentation. We found no difference in need for amputation, RFS, or OS between those who had undergone a planned excision and those who had an unplanned excision.

Conclusion

While we were unable to find a significant difference in outcomes or amputation rates between those who underwent reexcision of a previously unplanned excision and those who underwent an initial planned resection, the high rate of unplanned excision is troubling and should remind practitioners to consider sarcoma in the differential of all upper extremity masses.

Intracranial synovial sarcoma: A clinical, radiological and pathological study of 16 cases

INTRODUCTION

Synovial sarcoma (SS) is a tumor of unknown origin and is extremely rare in the central nervous system. Most studies on intracranial SS included only one or two cases. To better understand the disease, we review a series of primary intracranial SS.

METHOD AND MATERIALS

16 primary intracranial SS in Tiantan Hospital during 2008-2017 were included. The clinical characteristics, including radiological and histological examination, operative records, and prognoses were reviewed.

RESULT

The case series included nine male and seven female patients with an average age of 23.8 years. Radiological results showed that the supratentorial region (81.25%) was the most common site of the brain involved. All patients were misdiagnosed as non-SS tumors. Gross total resection (GTR) was achieved in 12 cases (75.0%), and subtotal resection (STR) was achieved in 4 cases. All cases showed the characteristic SYT-SSX fusion gene, as detected by RT-PCR. The mean progression-free survival time (PFS) was 10.0 months and the mean overall survival time (OS) was 15.5 months. Multivariate analysis revealed that GTR and postoperative adjuvant radiotherapy were independent factors for PFS (HR = 6.143, 95% CI = 1.491-25.312; P = 0.012, HR = 6.143, 95% CI = 1.491-25.312; P = 0.012 respectively) and OS (HR = 9.000, 95% CI = 1.627-49.773; P = 0.012, HR = 0.017, 95% CI = 0.001-0.213; P = 0.002 respectively).

CONCLUSION

Intracranial SS were more frequently observed in the supratentorial region and in young patients without sex predilection. We recommend adjuvant radiation regardless of the extent of resection. More patients and longer follow-up periods were needed to further elucidate the biological features of intracranial SS.

Well-differentiated liposarcoma and dedifferentiated liposarcoma: An updated review

Well-differentiated liposarcoma (WDL)/atypical lipomatous tumor and dedifferentiated liposarcoma (DDL) together comprise the largest subgroup of liposarcomas, and constitute a histologic and behavioral spectrum of one disease. WDL and DDL typically occur in middle-aged to older adults, particularly within the retroperitoneum or extremities. WDL closely resembles mature adipose tissue, but typically shows fibrous septation with variable nuclear atypia and enlargement. WDL does not metastasize, but can dedifferentiate to DDL, which is associated with more aggressive clinical behavior, with a greater propensity for local recurrence and the capacity for metastasis. Although distant metastasis is rarer in DDL compared with other pleomorphic sarcomas, behavior is related to location, with a significantly worse outcome in retroperitoneal tumors. DDL typically has the appearance of undifferentiated pleomorphic or spindle cell sarcoma, and is usually a non-lipogenic sarcoma that is adjacent to WDL, occurs as a recurrence of WDL or which can arise de novo. WDL and DDL share similar background genetic aberrations; both are associated with high-level amplifications in the chromosomal 12q13-15 region, which includes the CDK4 and MDM2 cell cycle oncogenes. In addition, DDL harbor further genetic changes, particularly 6q23 and 1p32 coamplifications. While surgical excision remains the treatment mainstay with limited medical options for patients with aggressive recurrent disease or metastases, novel targeted therapies towards the gene products of chromosome 12 are being evaluated. This review summarizes the pathology of WDL and DDL, discussing morphology, immunohistochemistry, genetics and the differential diagnosis.

Neutrophil/lymphocyte ratio is associated with survival in synovial sarcoma

BACKGROUND

Synovial sarcoma is a rare malignant soft tissue tumor, more common in adolescents and young adults and entails a poor prognosis. Several good prognostic factors have been well established such as age less than 25, size less than 5 cm and absence of a poorly differentiated component. Inflammation has a well-established role in tumor proliferation and survival. The aim of this study was to investigate the prognostic significance of the neutrophil/lymphocyte ratio (NLR) in a large cohort of synovial sarcoma patients.

METHODS

Retrospective study of 169 consecutive patients. We analyzed the relation of preoperative NLR on disease-free survival (DFS) and overall survival (OS) using Kaplan-Meier curves and Cox proportional models.

RESULTS

Of the 169 patients included, there were 90(53.3%) females and 79(46.7%) males. Median age was 32yo (11-73). Median survival was 34.1 and mean disease-free survival was 21.4 months. Mean tumor size was 12.5 cm (1.2-77 cm). Applying receiver operating curve analysis, we determined a cut-off value of 3.5. In univariate and multivariate analysis, increased NLR was significantly associated with poor OS. A <3.5 NLR was an independent prognostic factor in all stages (p = 0.002).

CONCLUSIONS

NLR >3.5 was found to be a reliable prognostic factor in this cohort. Given its widespread availability, we believe it's use in clinical practice and further clinical trials should be considered.

Disruption of mammalian SWI/SNF and polycomb complexes in human sarcomas: mechanisms and therapeutic opportunities

Soft-tissue sarcomas are increasingly characterized and subclassified by genetic abnormalities that represent underlying drivers of their pathology. Hallmark tumor suppressor gene mutations and pathognomonic gene fusions collectively account for approximately one-third of all sarcomas. These genetic abnormalities most often result in global transcriptional misregulation via disruption of protein regulatory complexes which govern chromatin architecture. Specifically, alterations to mammalian SWI/SNF (mSWI/SNF or BAF) ATP-dependent chromatin remodeling complexes and polycomb repressive complexes cause disease-specific changes in chromatin architecture and gene expression across a number of sarcoma subtypes. Understanding the functions of chromatin regulatory complexes and the mechanisms underpinning their roles in oncogenesis will be required for the design and development of new therapeutic strategies in sarcomas. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Cytologic diagnosis of round cell sarcomas in the era of ancillary testing: an updated review

Round cell sarcomas constitute a large proportion of "small round blue cell tumors," which encompass a broad differential diagnosis and can be difficult to distinguish on cytomorphologic grounds alone. Numerous pathogenetic insights and advances in ancillary testing in soft tissue pathology over the last several decades have made accurate classification of soft tissue neoplasms increasingly feasible. Immunohistochemistry and genetic/molecular testing can now be performed on all cytologic preparations, including unstained smears, needle rinses, cell blocks, and liquid-based preparations, and this has greatly increased our diagnostic abilities. Nevertheless, there remain numerous diagnostic challenges, including variable sensitivity and specificity of available immunohistochemical markers, overlapping immunophenotypes between entities, and "promiscuity" of genetic alterations such as EWSR1 rearrangements, present in a multitude of tumor types. Herein we provide a review on the cytologic, immunohistochemical, and genetic features of the more frequently encountered round cell sarcomas, as well as recently described entities, with an emphasis on diagnostic pitfalls and judicious use of ancillary studies.

Enhancer of zeste homologue 2 (EZH2) expression in synovial sarcomas as a promising indicator of prognosis

Synovial sarcoma (SS) is a type of soft-tissue sarcoma, often linked to poor survival. Although overexpression of enhancer of zeste homologue 2 (EZH2) has been associated with poor prognosis in different tumors, a few studies investigated this link in SS. Here, we analyzed the relationship between EZH2 expression and prognostic factors in SS. We included 29 patients with SS. Immunostaining of EZH2 was performed with (D2C9) XPTM Rabbit mAb antibody, and the results were classified as low EZH2 expression (negative or weak expression) and high EZH2 expression category (moderate or strong expression). Analysis of survival in relation to prognostic factors was performed with Kaplan-Meier survival curves and Cox proportional hazard regression analysis. Our sample included 19/29 female and 10/29 male patients, with age range 16-63 years. The tumor diameter ranged from 2 to 15 cm. Necrosis was observed in 15/29 cases. Sixteen cases had >10 mitoses per 50 high-power fields (HPFs). Out of 29 cases, 14 showed low and 15 had high EZH2 expression. Statistically significant results were obtained for the association between the presence of metastasis and necrosis (p = 0.042), high EZH2 expression and distant metastasis (p = 0.018), high EZH2 expression and necrosis (p = 0.016), and high EZH2 expression and the tumor size >5 cm versus tumor size ≤5 cm (p = 0.014). Patients with all of the following: the tumor size ≤5 cm, low EZH2 expression, and without necrosis and distant metastasis had significantly longer survival time. Our results are consistent with previous studies, suggesting that EZH2 overexpression is an indicator of poor prognosis in SS.

Unusual presentation of poorly differentiated primary pulmonary synovial sarcoma (PD-PPSS) diagnosed by EBUS-TBNA with cytogenetic confirmation-A diagnostic challenge

Poorly differentiated primary pulmonary synovial sarcoma (PD-PPSS) is a rare, aggressive neoplasm, which occurs in 0.5% cases of all lung malignancies. The diagnosis of PD-PPSS can be very challenging on cytology samples. We present here an unusual case of PD-PPSS diagnosed by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA), in the setting of known history of diffuse large B-cell lymphoma. Diff-Quik and Papanicolaou stains showed cellular specimen with clusters of highly atypical small round blue cells admixed with lymphoid elements; and some with denuded cytoplasm. Cell block further showed molding, crush artifact and atypical mitotic figures. A differential diagnosis based on extended immunohistochemical work-up was Ewing?s sarcoma/PNET versus poorly differentiated synovial sarcoma. Fluorescent in-situ hybridization (FISH) showed SYT gene rearrangement at 18q11.2. In this report, we describe the cytomorphological features, diagnostic pitfalls, challenges, potential mimics, and importance of acquisition of adequate material for the ancillary work-up on the cell block.

Synovial Sarcoma: Advances in Diagnosis and Treatment Identification of New Biologic Targets to Improve Multimodal Therapy

Synovial sarcoma is a translocation-associated soft-tissue malignancy that frequently affects adolescents and young adults. It is driven by one of the fusion oncoproteins SS18-SSX1, SS18-SSX2, or rarely, SS18-SSX4. Prognosis of patients with recurrent or metastatic disease is generally poor, and newer therapeutic strategies are needed. In this review, we present recent discoveries in the pathogenesis, diagnosis, and treatment of synovial sarcoma. We discuss potential therapeutic strategies to improve clinical outcomes in this disease.

Cancer-testis antigen expression in synovial sarcoma: NY-ESO-1, PRAME, MAGEA4, and MAGEA1

Synovial sarcoma (SS) is regarded as a relatively chemosensitive sarcoma, but the prognosis of advanced SSs remains poor. Here we identified highly expressed cancer-testis antigens that could be promising immunotherapy targets for SS, using a previously conducted cDNA microarray, and we assessed the clinicopathological or prognostic relationships of these antigens in SS. We compared the gene expression profiles of 11 SSs with those of 3 normal adipose tissues. Among the up-regulated cancer-testis antigens, we analyzed PRAME, MAGEA1, and MAGEA4 and another cancer-testis antigen (NY-ESO-1) together, by immunohistochemistry and real-time polymerase chain reaction in 108 SSs. Immunohistochemically, NY-ESO-1, PRAME, MAGEA4, and MAGEA1 were positive in 66 (61%), 93 (86%), 89 (82%), and 16 (15%) of 108 SSs, respectively, and 104 (96%) of 108 SSs showed the immunohistochemical expression of at least 1 of NY-ESO-1, PRAME, and MAGEA4. Moreover, the high expression of at least 1 of these 3 antigens was observed in 83% of the SSs. High expression of NY-ESO-1 and MAGEA4 was significantly correlated with the presence of necrosis and advanced clinical stage. The immunohistochemical expression of these cancer-testis antigens was not correlated with prognosis, but the coexpression of NY-ESO-1, PRAME, and MAGEA4 was significantly associated with adverse prognosis. The real-time polymerase chain reaction results were closely related to the immunohistochemical results: NY-ESO-1 (P = .0019), PRAME (P = .039), MAGEA4 (P = .0149), and MAGEA1 (P = .0766). These data support the potential utility of NY-ESO-1, PRAME, and MAGEA4 as immunotherapy targets and ancillary prognostic parameters, suggesting the possible benefit of the combined use of these cancer-testis antigens as an SS immunotherapy target.

Ewing sarcoma: a chronicle of molecular pathogenesis

Sarcomas have traditionally been classified according to their chromosomal alterations regardless of whether they accompany simple or complex genetic changes. Ewing sarcoma, a classic small round cell bone tumor, is a well-known mesenchymal malignancy that results from simple sarcoma-specific genetic alterations. The genetic alterations are translocations between genes of the TET/FET family (TLS/FUS, EWSR1, and TAF15) and genes of the E26 transformation-specific (ETS) family. In this review, we intend to summarize a chronicle of molecular findings of Ewing sarcoma including recent advances and explain resultant molecular pathogenesis.

Monosomy 22 and partial loss of INI1 expression in a biphasic synovial sarcoma with an Ewing sarcoma-like poorly differentiated component: Report of a case

Poorly differentiated synovial sarcoma (PDSS) is a less common subtype of synovial sarcoma (SS) associated with a poor prognosis. We present a case of a SS with a poorly differentiated component that resembles Ewing sarcoma (ES). Initial immunohistochemical staining revealed a characteristic and strong expression of transducin-like enhancer of split 1 (TLE1) and weak to absent expression of integrase integrator 1 (INI1) staining. Stainings for keratin and epithelial membrane antigen (EMA) were negative in the tumoral lesion. Fluorescence In Situ Hybridization (FISH) analysis showed a rearrangement of the synaptotagmin (SYT) gene, confirming the diagnosis of SS. FISH analysis for the EWS RNA-binding protein 1 (EWSR1) gene revealed monoallelic loss of EWSR1. This finding was confirmed by an array comparative genomic hybridization (aCGH), showing complete loss of chromosome 22. Based on literature review, showing only a handful of cases of cytogenetically studied SS with loss of chromosome 22, this is probably a rare event in SS. Therefore, we assume that monoallelic loss of chromosome 22 cannot fully elaborate the underlying mechanism of the INI1 staining pattern in all SS, but it could account for the weak to absent INI1 staining in at least some cases.

Primitive Round Cell Neoplasms

Primitive round cell neoplasms (small round cell tumors) of soft tissue are a diverse group of malignant tumors composed of monotonous undifferentiated cells with high nuclear-cytoplasmic ratio. Many occur more frequently, although not exclusively, in childhood. As tumors with primitive round cell morphology are seen in virtually every basic tumor category, the diagnosis of small round cell neoplasms requires the use of ancillary diagnostic techniques: immunohistochemistry and often molecular genetics. The principal tumors in this group include Ewing sarcoma/primitive neuroectodermal tumor, desmoplastic small round cell tumor, alveolar rhabdomyosarcoma, poorly differentiated synovial sarcoma, neuroblastoma, and ganglioneuroblastoma.

Epithelioid Sarcoma: Diagnostic Features and Genetics

Epithelioid sarcoma (ES) is a rare, aggressive soft-tissue neoplasm of uncertain differentiation, characterized by nodular aggregates of epithelioid cells, which are immunoreactive to cytokeratins (CKs) and epithelial membrane antigen, and often for CD34. It has a propensity for multifocal disease at presentation, local recurrence, and regional metastasis. These are aggressive neoplasms with particularly poor prognosis after regional or distant metastatic disease, for which surgical resection is still the mainstay of treatment, and options for patients with metastatic disease remain undefined. There are 2 distinct variants: classic ES, which typically presents as a subcutaneous or deep dermal mass in the distal extremities of young adults and comprises nodular distributions of relatively uniform epithelioid cells with central necrosis, and the proximal variant, which has a predilection for proximal limbs and limb girdles and the midline of the trunk, which is composed of sheets of larger, more atypical cells with variable rhabdoid morphology. Both classic and proximal-type ESs are associated with the loss of SMARCB1/INI1 protein expression, but appear otherwise molecularly relatively heterogeneous. We review classic and proximal-type ES, discussing morphology, immunohistochemical and genetic findings, the differential diagnosis, and the future potential for targeted therapies.

Dedifferentiated Liposarcoma: Updates on Morphology, Genetics, and Therapeutic Strategies

Well-differentiated liposarcoma (WDL) and dedifferentiated liposarcoma (DDL) form the largest subgroup of liposarcomas, and represent a morphologic and behavioral spectrum of 1 disease entity, which arises typically in middle to late adult life, most frequently within the retroperitoneum or extremities. DDL is defined as nonlipogenic sarcoma that is juxtaposed to WDL, occurs as a recurrence of WDL or which can arise de novo, and typically has the appearance of undifferentiated pleomorphic or spindle cell sarcoma. DDL have a propensity for local recurrence, whereas distant metastasis is rarer, and behavior is related to anatomic site, with retroperitoneal neoplasms showing a significantly worse prognosis. Surgical resection remains the mainstay of treatment, and medical options for patients with aggressive recurrent or metastatic disease are limited. DDL share similar genetic abnormalities to WDL, with high-level amplifications of chromosome 12q14-15, including the MDM2 and CDK4 cell cycle oncogenes, and DDL harbor additional genetic changes, particularly coamplifications of 6q23 and 1p32. Novel therapies targeted at the gene products of chromosome 12 are being tested in clinical trials. We review the pathology and genetics of DDL, discussing morphologic patterns, immunohistochemical and genetic findings, the differential diagnosis, and future therapeutic strategies.

The diagnostic utility of reduced immunohistochemical expression of SMARCB1 in synovial sarcomas: a validation study

Synovial sarcoma is a malignant mesenchymal neoplasm of uncertain histogenesis, characterized by a specific SS18-SSX fusion. The diagnosis of synovial sarcoma can be challenging based on morphology and conventional immunohistochemistry alone, and identification of the fusion gene by molecular genetics may be necessary for diagnosis. Several recent studies have demonstrated the diagnostic utility of the reduced expression of SMARCB1 in synovial sarcomas as measured using immunohistochemistry. Therefore, we undertook a validation study using synovial sarcomas and other spindle or round cell tumors that could enter differential diagnosis of monophasic or poorly differentiated synovial sarcomas. Among 36 synovial sarcomas that were successfully evaluated, the expression of SMARCB1 was diffusely reduced in 33 cases (92%) at variable degrees. In contrast, the expression of SMARCB1 was not reduced in any of the 93 evaluable non-synovial sarcoma tumors (5 thymomas, 5 sarcomatoid mesotheliomas, 10 schwannomas, 9 mesenchymal chondrosarcomas, 20 solitary fibrous tumors, 19 Ewing sarcomas, and 25 malignant peripheral nerve sheath tumors). A few schwannomas and malignant peripheral nerve sheath tumors showed mosaic or complete loss of SMARCB1 expression. Reduced expression of SMARCB1 immunoreactivity was therefore found to be highly sensitive and specific for synovial sarcoma, and can be useful for rapidly and accurately confirming the diagnosis of synovial sarcoma. This reduction in SMARCB1 expression likely reflects the BAF47 ejection mechanism of the SS18-SSX fusion product and can therefore be viewed as an indirect visualization of this fusion product.

Primary Synovial Sarcoma (SS) of the digestive system: a molecular and clinicopathological study of fifteen cases

BACKGROUND

Recently a few cases of synovial sarcoma (SS) of the abdominal viscera have been reported, raising awareness about the potential for confusion between this entity and KIT-negative gastrointestinal stromal tumors (GIST). We report the clinicopathological, immunophenotypical and molecular features of fifteen more SS occurring in the stomach (8 cases), epigastric region (one case), small intestine (one case), large intestine (three cases), involving both the terminal ileum and the caecum (one case) and liver (one case).

METHODS

Immunostains for SMA, DESMIN, CD34, CD117, S100, EMA, CK AE1/3, TLE1, CD56, CD99, BCL2, DOG1 were performed. Rearrangement of SS18 gene region was screened in all cases: by conventional karyotype in one case, the remaining cases were screened either by interphase FISH or Q-PCR or both.

RESULTS

Ten patients were male and five female, with an age range of 17-61 years (median 44). Tumor size ranged from 2 to 15 cm (median 8). Mitoses per 10 HPF ranged from 4 to 27 (median 9.5). Eleven tumors were monophasic fibrous SS, one biphasic SS and three poorly differentiated SS. SMA, Desmin, CD34, CD117 and S100 were negative in all cases, whereas EMA and/or CK AE1/AE3 were positive in all cases. TLE1, BCL2 and CD56 were positive in all tested cases. DOG1 was positive in one case. SS18 gene region rearrangement was demonstrated in all cases. A fusion transcript was amplified in eight cases: either SS18-SSX2 or SS18-SSX1 respectively in four cases each.

CONCLUSIONS

SS is increasingly recognized at visceral sites. Molecular analyses play a key role when dealing with usual histotypes in unusual sites. Correct diagnosis is crucial for appropriate therapy.

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.

Primary pulmonary poorly differentiated synovial sarcoma: transducer-like enhancer of split 1 immunohistochemistry as a valuable diagnostic aid

Poorly differentiated primary pulmonary synovial sarcomas are rare and challenging for a surgical pathologist to diagnose. Although the demonstration of the tumor specific translocation, t (x; 18)(p11.2;q11.2) or the resultant fusion gene (SYT-SSX) is the gold standard for diagnosis, this test is not always accessible. We report the use of immunohistochemistry, including transducer-like enhancer of split-1 in the diagnosis of one such tumor in a young individual.