Pericardium: an exceedingly rare site for a primary biphasic synovial sarcoma

Pericardial neoplasms are rare. Among pericardial neoplasms, metastatic spread is more common and primary synovial sarcomas of the pericardium are exceedingly rare. A 61-year-old man was found dead in bed. Autopsy revealed the cause of death as atherosclerotic and hypertensive heart disease. There was a pericardial soft tissue mass lying predominantly over the left atrium. The cut surface was bulging out and grayish white in color with cystic changes. Microscopy showed spindle cells in densely cellular fascicles surrounding the epithelial cells. The epithelial cells were cuboidal and formed glandular structures and cleft-like spaces. Immunohistochemistry demonstrated cytokeratin and vimentin positivity in the spindled areas. Molecular analysis confirmed the diagnosis. Synovial sarcoma may be mistaken for other common neoplasms occurring in the pericardium due to its rarity. In all cases of pericardial tumors, a diligent search for synovial sarcoma by way of histological analysis including, immunohistochemistry and molecular analysis is indicated.     

34例滑膜肉瘤分子遗传学改变的诊断学意义

目的 探讨石蜡包埋滑膜肉瘤组织中t(x；18)(p11．2；q11．2)染色体易位融合基因SYT-SSX mRNA表达的诊断学意义和应用价值。方法 收集滑膜肉瘤标本34例，以14例梭形细胞肉瘤和小圆细胞肉瘤做对照(包括2例纤维肉瘤、2例平滑肌肉瘤、1例恶性神经鞘膜瘤、4例Ewing肉瘤、2例腺泡型横纹肌肉瘤、2例恶性黑色素瘤、1例血管外皮瘤)。在进行免疫组织化学指标检测的基础上，用一步法逆转录-聚合酶链反应(RT-PCR)技术检测34例石蜡包埋滑膜肉瘤组织中SYT-SSX的表达。结果 34例滑膜肉瘤中30例获得有效RNA，28例(93．3％)检出SYT-SSX融合基因表达。其中14例表达SYT-SSXl型者中10例为双相型，9例表达SYT-SSX2型者中5例为单相分化型，5例SYT-SSXl／2均未检出。对照组均未检出SYT-SSX基因的表达。结论 SYT-SSX融合基因表达可作为诊断滑膜肉瘤新的分子诊断指标。一步法RT-PCR是一种理想而可行的用于石蜡包埋滑膜肉瘤组织SYT-SSX融合基因检测的分子诊断技术。     

低分化滑膜肉瘤临床病理及分子遗传学研究

目的：研究低分化滑膜肉瘤的临床病理学特点及其分子遗传学表现。方法：收集低分化滑膜肉瘤标本121例，采用形态学观察和免疫组化染色，并用RT－PCR方法在石膜包埋组织中检测SYT－SSX融合mRNA表达。结果：12例低分化滑膜肉瘤中细胞型4例，大细胞型6例，高度恶性梭形细胞型2例。8例有随访资料其中4例死于肿瘤，平均生存时间18个月。免疫组化表现为CK和（或）EMA阳性，以EMA阳性率较高，同时vimentin阳性。S－100蛋白也有较高阳性率，多呈局灶或散在阳性。RT－PCR方法均可检测到SYT－SSXmRNA表达，对照组12例肿瘤包括恶性周围神经 鞘膜瘤、尤因肉瘤和恶性血管外皮瘤SYT－SSX检测全部阴性。结论：低分化滑膜肉瘤有其形态学及免疫表型特点，分子遗传学检测SYS－SSX融合mRNA有助于诊断和鉴别诊断。     

Stem cell transcription factor SOX2 in synovial sarcoma and other soft tissue tumors

Background

SOX2 has gained considerable interest as a pluripotency inducing gene. Co-transfection of SOX2 together with NANOG, KLF4 and c-MYC into adult fibroblasts was able to generate pluripotent stem cells. SOX2 has been reported to be expressed in synovial sarcoma, a tumor being characterized by the SS18-SSX gene fusion forming part of the SWI/SNF chromatin remodeling complex that affects histone methylation. The role of SOX2 in this tumor type as well as other soft tissue tumor entities however is still poorly characterized. We analyzed SOX2 protein expression in soft tissue tumors. Alongside we tested Histone H3 expression (H3K27me3) in SOX2 positive cases to investigate this epigenetic mark and its correlation with the SOX2 status and clinicopathological parameters.

SYT-SSX2 variant of primary pulmonary synovial sarcoma with focal expression of CD117 (c-Kit) protein and a poor clinical outcome

Pulmonary synovial sarcoma is a rare neoplasm recently recognized as a distinct entity and characterized by t(X;18) translocation and production of at least 2 fusion genes, SYT-SSX1 and SYT-SSX2. We report a case of primary pulmonary synovial sarcoma with the SYT-SSX2 phenotype and a rapidly progressive downhill course. Previous reports have suggested that the soft tissue synovial sarcomas with SYT-SSX2 phenotype have a favorable clinical outcome. To the best of our knowledge, this is also the first report of CD117 (c-Kit) expression in a pulmonary synovial sarcoma. A 45-year-old woman presented with left chest pain and was found to have a left lower lobe tumor that was originally diagnosed as a sarcomatoid carcinoma. After the patient underwent chemotherapy and brachytherapy, the specimen from a left pneumonectomy showed a large spindle cell tumor, which was reclassified as a synovial sarcoma based on the results of immunophenotyping and molecular genetic studies. Differentiation between sarcoma and carcinosarcoma is crucial for implementing appropriate therapy. Furthermore, if the tumor expresses c-Kit, it may respond to target-based therapy.     

Fine-needle aspiration of synovial sarcoma: criteria for diagnosis: retrospective reexamination of 37 cases,including ancillary diagnostics. A Scandinavian Sarcoma Group study

The cytologic criteria of synovial sarcoma in fine-needle aspirates were defined by a retrospective examination of 37 primary tumors. Irrespective of subtype, a typical pattern at low power was found, provided the yield was rich. The typical pattern was a mixture of dispersed cells with the presence of striped nuclei and cell-tight tumor tissue fragments with irregular borders. Often a branching network of vessels was present in the fragments, imitating a true vascular tumor. Except in poorly differentiated synovial sarcomas, the tumor cells were, small to medium in size, with rounded, ovoid, or fusiform bland nuclei with inconspicuous nucleoli. In the biphasic variant, small glandular- or acinar-like structures were present, although not in all cases. In the poorly differentiated type, however, the cellular pleomorphism was marked with the presence of cells with irregular nuclei and rhabdomyoblast-like cells, corresponding to the pleomorphic variant. The Ewing's sarcoma-like and the atypical spindle cell variants of poorly differentiated synovial sarcoma were not diagnosed in the material. An unequivocal diagnosis of sarcoma is possible when the yield is rich. However, ancillary diagnostics are necessary for a correct diagnosis, to avoid important pitfalls, such as other sarcomas with bland tumor cells and vessel-rich tumor fragments, in particular, solitary fibrous tumor and true hemangiopericytoma. Electron microscopic and/or molecular genetic analyses were better diagnostic adjuncts than immunocytochemistry.     

Immunostaining for SYT protein discriminates synovial sarcoma from other soft tissue tumors: analysis of 146 cases.

Synovial sarcoma in its classic biphasic form can be distinguished readily from other soft tissue lesions; however, monophasic and poorly differentiated forms are diagnostically more problematic. For this reason, we assessed the efficacy of immunostaining for SYT and SSX1 proteins, the gene products resulting from unique synovial sarcoma translocation, to distinguish synovial sarcoma from other soft tissue lesions. A total number of 146 cases were analyzed, including 47 synovial sarcoma cases (all of which were verified by FISH to have t(X; 18) translocation and SYT-SSX fusion gene) and 99 soft tissue tumors of various types. A polyclonal IgG antibody against SYT was used to stain formalin-fixed paraffin embedded tissues. Forty-one out of 47 (87%) synovial sarcoma displayed strong positive nuclear staining (ranging from 80 to 90% of the tumor cells) for SYT antibody. Nineteen of 99 (19%) non-synovial sarcoma cases showed variable nuclear and cytoplasmic staining with SYT, which ranged from 20 to 60% of tumor nuclei, and included malignant peripheral nerve sheath tumor (5/25), solitary fibrous tumor (2/14), Ewing sarcoma (2/6), low grade fibromyxoid tumor (2/4), extraskeletal mesenchymal chondrosarcoma (2/6), gastrointestinal tumor (4/17), epithelioid sarcoma (2/2). The remaining non-synovial sarcomas were negative. This is the first study demonstrating SYT protein expression in tissue sections of synovial sarcoma. This method could provide an easy, rapid and widely applicable means of assisting in the diagnosis of synovial sarcoma, particularly when material and/or resources are unavailable for PCR or FISH-based testing. However, as variable weak staining for SYT may be encountered in a small percentage of non-synovial sarcoma sarcomas, a positive interpretation should be made only when the staining is strong, nuclear and present in the majority of cells.     

NY-ESO-1 expression in synovial sarcoma and other mesenchymal tumors: significance for NY-ESO-1-based targeted therapy and differential diagnosis

A promising targeted therapy against NY-ESO-1 (CTAG 1B) using genetically modified T-cells in synovial sarcomas was recently demonstrated in a clinical trial at the NCI. To investigate the role of NY-ESO-1 immunohistochemistry in patient selection and gain better insight into the incidence of NY-ESO-1 expression in synovial sarcomas and other mesenchymal tumors, we evaluated NY-ESO-1 expression by immunohistochemistry in 417 tumors. This collection of samples included: 50 SS18/SSX1/2 fusion positive synovial sarcomas, 155 gastrointestinal stromal tumors (GIST), 135 other spindle cell sarcomas as well as 77 other sarcomas (chondrosarcoma, osteosarcoma, dedifferentiated liposarcoma, alveolar soft part sarcoma, rhabdomyosarcoma, angiosarcoma, malignant mesothelioma, and Ewing's sarcoma). We report that 76% of synovial sarcomas expressed NY-ESO-1 in a strong and diffuse pattern (2-3+, >50-70% of tumor cells). In contrast, only rare cases of other spindle cell mesenchymal tumor expressed NY-ESO-1 (GIST (2/155), malignant peripheral nerve sheath tumors (1/34), and dermatofibrosarcoma protuberans (2/20)). Individual cases of other sarcomas (angiosarcoma, malignant mesothelioma, chondrosarcoma, osteosarcoma, dedifferentiated liposarcoma, alveolar soft part sarcoma, and Ewing's sarcoma) were positive for NY-ESO-1. However, no positive cases were identified amongst our cohort of leiomyosarcomas (0/24), hemangiopericytoma/solitary fibrous tumors (0/40), and cellular schwannomas (0/17). In summary, we find that NY-ESO-1 is strongly and diffusely expressed in a majority of synovial sarcomas, but only rarely in other mesenchymal lesions. Beyond its role in patient selection for targeted therapy, immunohistochemistry for NY-ESO-1 may be diagnostically useful for the distinction of synovial sarcoma from other spindle cell neoplasms.     

Cellular differentiation of epithelioid sarcoma. An electron-microscopic, enzyme-histochemical, and immunohistochemical study.

For the purpose of clarifying cellular differentiation of epithelioid sarcoma, studies based on various methods were performed. Enzyme histochemical studies showed that epithelioid sarcoma tumor cells have characteristics intermediate between epithelial cells and the large plump cells of synovial sarcoma-incomplete epithelial differentiation. For alkaline phosphatase and adenosine triphosphatase particularly, positive cells and negative cells coexisted, as in the large plump cells of synovial sarcoma. Immunohistochemical studies for alpha 1-antitrypsin, alpha 1-antichymotrypsin, vimentin, and keratin also showed that epithelioid sarcoma tumor cells are very similar to the large plump cells of synovial sarcoma and have incomplete epithelial differentiation. For example, the examinations of serial sections and double staining methods revealed that keratin-positive cells are always vimentin-positive in epithelioid sarcoma and in the monophasic area of synovial sarcoma. Electron-microscopically, bundles of intermediate filaments and filopodia toward the intercellular lumen were observed, as in the monophasic area of synovial sarcoma. The results of enzyme-histochemical and immunohistochemical studies of non-neoplastic synovial lining cells, performed here for the first time, are also discussed.     

Pulmonary synovial sarcoma with polypoid endobronchial growth: a case report, immunohistochemical and cytogenetic study

A rare case of primary pulmonary synovial sarcoma with polypoid endobronchial growth in a 42-year-old Japanese woman is described. Left upper sleeve lobectomy was performed for the polypoid tumor measuring 2.5 cm in the left major bronchus and the patient was treated with adjuvant chemotherapy. Three years later, a recurrent tumor was discovered. Microscopically, this tumor was characterized by a proliferation of oval to spindle-shaped cells arranged in sheets and fascicles and covered by the thin normal bronchial epithelium. Immunohistochemically, tumor cells were positive for vimentin, and focally positive for pancytokeratin recognized by AE1/AE3, cytokeratin 7 and epithelial membrane antigen. A chimera gene, SYT-SSX1, was detected. Recently, primary pulmonary synovial sarcoma is an increasingly recognized clinical entity; however, most of these tumors present as a parenchymal mass. The present case is a unique example of primary synovial sarcoma of endobronchial polypoid type. This case suggests that pulmonary synovial sarcoma might originate from bronchial submucosal stromal tissue.     

Synovial sarcoma of the upper digestive tract: a report of two cases with demonstration of the X;18 translocation by fluorescence in situ hybridization.

Two cases of synovial sarcoma that arose in the upper digestive tract are reported. One case was a polypoid mass that arose at the gastroesophageal junction; the other was a large intramural mass that arose in the wall of the stomach. Both cases had a classic biphasic pattern. In the stomach tumor, the biphasic morphology was focal and there was an abrupt transition to poorly differentiated synovial sarcoma. The tumors had immunohistochemical features that were consistent with synovial sarcoma. Ultrastructural evaluation of the gastroesophageal tumor supported the diagnosis. The diagnostic X;18 translocation was demonstrated by fluorescence in situ hybridization on sections from paraffin-embedded tissue in 86% and 50% of interphase nuclei from the gastroesophageal and gastric tumor, respectively. The translocation was present in equal frequency in the epithelial and spindle cells in the biphasic areas and the poorly differentiated areas of the gastric tumor, indicating that the development of the more aggressive subclone was probably due to genetic mutations not encompassing the SYT-SSX gene fusion product. We are aware of only five reported cases of synovial sarcoma arising in the digestive tract, all in the proximal esophagus. These cases are the first reported arising in the gastroesophageal junction and stomach and the only cases of synovial sarcoma of the digestive tract in which the diagnostic translocation was demonstrated. Sarcomatoid carcinoma (carcinosarcoma) and gastrointestinal stromal tumor are the main differential diagnoses for synovial sarcoma in this site. Synovial sarcoma of the digestive tract may be underdiagnosed, and its recognition may have important clinical implications. Fluorescence in situ hybridization is helpful in making this distinction.     

滑膜肉瘤中E-、N-cadherin和β-catenin的表达及意义

目的探讨上皮间叶转化(EMT)相关蛋白E-、N-cadherin和β-catenin在滑膜肉瘤中的表达及意义。方法收集滑膜肉瘤34例,包括双相型24例和单相纤维型10例,应用免疫组化EnVision两步法检测E-、N-cadherin和β-catenin的蛋白表达水平。结果 (1)E-、N-cadherin和β-catenin在34例滑膜肉瘤中的阳性率分别为52.9%、76.5%、97.1%。E-cadherin在双相型滑膜肉瘤中的阳性率(70.8%)高于单相纤维型(10%)(P<0.05);N-cadherin、β-catenin在双相型和单相纤维型滑膜肉瘤中的阳性率分别为70.8%(17/24)和90%(9/10)、95.8%(23/24)和100%(24/24),差异均无显著性(P>0.05)。(2)在24例双相型梭形细胞成分中E-、N-cadherin和β-catenin的阳性率分别为12.5%(3/24)、50%(12/24)和62.5%(15/24);在10例单相纤维型滑膜肉瘤梭形细胞成分中的阳性率分别为10%(1/10)、80%(8/10)和100%(10/10)。β-catenin在单相纤维型滑膜肉瘤的梭形细胞的表达率高于双相型中的梭形细胞(P<0.05)。(3)在24例双相型滑膜肉瘤中,E-、N-cadherin和β-catenin在上皮样细胞中的阳性率分别为70.8%(17/24)、83.3%(20/24)和95.8%(23/24);在梭形细胞成分中的阳性率分别为12.5%(3/24)、50%(12/24)和62.5%(15/24)。E-、N-cadherin和β-catenin在上皮样细胞中的表达均高于梭形细胞(P<0.05)。(4)在双相型滑膜肉瘤中E-cadherin和N-cadherin、E-cadherin和β-catenin均同时表达的比例较高,在单相纤维型中E-cadherin不表达而N-cadherin、β-catenin表达的比例较高。(5)滑膜肉瘤中E-、N-cadherin和β-catenin的表达与患者年龄、肿瘤大小、组织学分级和临床TNM分期之间差异均无显著性(P>0.05)。结论 EMT相关蛋白E-、N-cadherin和β-catenin均可能参与滑膜肉瘤的组织形态分化,N-cadherin和β-catenin影响双相型和单相纤维型滑膜肉瘤中E-cadherin的表达途径不同,滑膜肉瘤组织中可能存在间叶上皮转化(MET)现象。对其深入研究将有助于阐明滑膜肉瘤浸润和转移的分子机制。     

Chromosomal translocation t(X;18) in human synovial sarcomas analyzed by fluorescence in situ hybridization using paraffin-embedded tissue.

Synovial sarcoma is characterized cytogenetically by translocation t(X;18)(p11.2;q11.2). In this study, 28 cases that had been diagnosed initially as synovial sarcoma, including 2 fibrosarcomas, and 1 leiomyosarcoma were collected and examined for translocation t(X;18) on paraffin-embedded tissues by fluorescence in situ hybridization (FISH). Of the synovial sarcomas, 25 showed findings consistent with translocation t(X;18) with an additional copy signal for the total probe of X and 18 chromosomes. The other three cases, as well as the two fibrosarcomas and the leiomyosarcoma, did not show this translocation. One (case 26) of three negative cases was diagnosed finally as leiomyosarcoma and another (case 27) as malignant peripheral nerve sheath tumor from histological and immunohistochemical analysis. Thus, in all, 25 (96%) of 26 synovial sarcomas showed findings consistent with translocation t(X;18). In summary, translocation t(X;18) is a chromosomal aberration specific for synovial sarcoma. The fluorescence in situ hybridization technique can be used even on cells from paraffin-embedded tissues, and is a useful diagnostic aid for synovial sarcoma.