Synovial sarcoma of the abdominal wall

Summary A synovial sarcoma of the abdominal wall in a 56-year old woman showed the typical features of this tumor type. Histologically a characteristic biphasic cellular pattern with epithelium-like cell complexes and sarcomatous spindle cell areas was found. The histochemical examination revealed that tumor cells synthesize glycoproteins and weakly acid glycosaminoglycans (mainly hyaluronic acid). Electron microscopically the tumor cells in epithelium-like cell islets were sometimes arranged in gland-like formations with microvilli at the luminal side, specialized intercellular junctions and a peripheral basement membrane-like condensation of the ground substance. There was no fundamental cytological difference between cells of epithelium-like and spindle cell areas. Generally the tumor cells imitated cells of the synovial membrane and we found no evidence for origin from cells of the nerve sheath. Because of the submicroscopic relationship and histochemical similarities of synovial sarcomas and mesotheliomas we suggest that they should be united in a group of sarcomas with possible biphasic cellular pattern, while preserving their clinicopathologic definition.     

Synovial sarcoma of nerve

Tumors of peripheral nerve are largely neuroectodermal in nature and derived from 2 elements of nerve, Schwann or perineurial cells. In contrast, mesenchymal tumors affecting peripheral nerve are rare and are derived mainly from epineurial connective tissue. The spectrum of the latter is broad and includes lipoma, vascular neoplasms, hematopoietic tumors, and even meningioma. Of malignant peripheral nerve neoplasms, the vast majority are primary peripheral nerve sheath tumors. Malignancies of mesenchymal type are much less common. To date, only 12 cases of synovial sarcoma of nerve have been described. Whereas in the past, parallels were drawn between synovial sarcoma and malignant glandular schwannoma, an uncommon form of malignant peripheral nerve sheath tumor, molecular genetics have since clarified the distinction. Herein, we report 10 additional examples of molecularly confirmed synovial sarcoma, all arising within minor or major nerves. Affecting 7 female and 3 male patients, 4 tumors occurred in pediatric patients. Clinically and radiologically, most lesions were initially thought to be benign nerve sheath tumors. On reinterpretation of imaging, they were considered indeterminate in nature with some features suspicious for malignancy. Synovial sarcoma of nerve, albeit rare, seems to behave in a manner similar to its more common, soft tissue counterpart. Those affecting nerve have a variable prognosis. Definitive recommendations regarding surgery and adjuvant therapies await additional reports and long-term follow-up. The literature is reviewed and a meta-analysis is performed with respect to clinicopathologic features versus outcome.     

Epithelial markers in synovial sarcoma

Summary Immunohistochemical studies on synovial sarcomas have proved the potentiality of these neoplasm for epithelial and mesenchymal differentiation and antibodies detecting epithelial cells have been found to be helpful in determining the histological types. In this study different epithelial markers directed against various cytokeratins, HMFG-2 and EMA were investigated on paraffin embedded tissues of 13 cases of synovial sarcomas, with regard to their reliability in unmasking the epithelial components demonstrable in this type of neoplasm. The results lead to three conclusions firstly, synovial sarcomas possess the capacity for generating different epithelial cell types with uncommon compositions of intermediate filaments as well as of membrane proteins, secondly, these features may be expressed in a heterogenous pattern even within the same tumour and finally, the use of wide range anti-cytokeratin antibodies covering the spectrum of basic as well as acidic type proteins seems to be necessary for the detection of all epithelial components demonstrable in synovial sarcomas.     

Recurrence of synovial sarcoma of the abdomen in a 10-year old child

The case of a 10 year old child with a synovial sarcoma of the left iliac fossa, which recurred 12 months after simple large surgical excision, is reported here. No related lesions and, in particular, no lesion of the articular capsule of the left hip could be found, either on X-ray or at the time of the two excisions. Microscopically, the tumor showed, in all the areas examined, the existence of two characteristic morphological aspects, associating epithelial like type cells and elongated fusiform cells. These features correspond exactly to the classic "biphasic" type of synovial sarcoma. This location of a synovial sarcoma is an uncommon one, both in children and in adults.     

Immunohistochemical analysis of extracellular matrix components in synovial sarcoma

Little attention has been paid to the composition of the extracellular matrix in synovial sarcoma, a tumour showing both epithelial and mesenchymal phenotypes. As extracellular matrix participates actively in interactions between epithelial and mesenchymal tissues, further knowledge of the pathogenesis of this tumour may be provided by the study of extracellular matrix components. Therefore, we have analysed the immunohistochemical distribution of type I, III, and IV collagen, fibronectin, laminin and tenascin in four cases of synovial sarcoma. The pattern of immunoreactivity for these molecules varied according to the tissue phenotype of the tumour. Mesenchymal tissue labelled mainly for type I and III interstitial collagen and fibronectin. The epithelial component was surrounded by a laminin and type IV collagen-positive basement membrane, but punctate pericellular reactivity for laminin and type IV collagen was also detected among some mesenchymal cells. Tenascin was strongly expressed in the mesenchymal tissue immediately around epithelial structures and weakly or not at all expressed in the monophasic tumours and in mesenchymal tissue distant from epithelial elements in the biphasic tumours. These results suggest some resemblances between synovial sarcoma and the embryonic development of epithelia from mesenchymal cells, providing further support for the concept of an epitheliogenesis from the mesenchyme in these tumours.     

Expression of c-Met receptor and hepatocyte growth factor/scatter factor in synovial sarcoma and epithelioid sarcoma

 Overexpression of c-Met receptor/hepatocyte growth factor (scatter factor) system (c-Met/HGF/SF) as a physiologically paracrine cellular signaling system is thought to be involved in the progression of malignant tumours. In 26 synovial sarcomas and epithelioid sarcomas, c-Met and HGF/SF expression was analysed immunohistochemically. There were 10 biphasic synovial sarcomas, 7 of which showed moderate to strong c-Met expression in epithelial areas compared with the fibrous component, with corresponding expression of HGF/SF. Six of 9 monophasic fibrous synovial sarcomas showed only very faint c-Met and corresponding HGF/SF expression. In 7 epithelioid sarcomas strong expression of c-Met and HGF/SF was observed within epithelioid tumour cells. Non-radioactive in situ hybridization demonstrated the synthesis of c-Met receptor in tumor cells by detecting c-met-mRNA. This analysis shows that in synovial sarcomas and epithelioid sarcomas, tumour entities with epithelial and mesenchymal structures, c-Met and HGF/SF overexpression can be detected, indicating a role of this signaling system in these subtypes of sarcoma, and especially in the more epithelioid tumour phenotype. An autocrine interaction between overexpressed c-Met receptor and HGF/SF may be hypothesized. Received: 21 July 1997 / Accepted: 19 November 1997     

Biphasic axillary synovial sarcoma diagnosed by preoperative fine‐needle aspiration cytology

Synovial sarcoma (SS) is a soft‐tissue sarcoma which usually occurs in lower extremities. Less than 20 cases of SS located in shoulder or axillary region have been reported, and these studies describe histopathological features. We report a case of axillary SS diagnosed by fine‐needle aspiration cytology, immunocytochemistry, and molecular techniques performed on cytology smears. A 48‐year‐old woman presented with a palpable and well‐defined axillary mass which measured 4 cm. On‐site smears showed high cellularity with spindle cells, and a mesenchymal tumor was suspected. Definitive cytological analysis showed cells with ovoid‐ or comma‐shaped nuclei arranged in loose sheets and fascicles, associated with naked nuclei and isolated cells. Mitotic count was 2 mitoses/HPF. Immunocytochemical studies showed vimentin and focal CK AE1‐AE3 positivity. A PCR was performed and the specific translocation t (X;18) was detected. The lesion was excised and the diagnosis of biphasic SS was confirmed. The identification of SS on cytology specimens is difficult and differential diagnosis is broad. Complementary studies are necessary and they can be performed on FNA smears or cell blocks.     

免疫组织化学染色和SYT-SSX融合基因检测在滑膜肉瘤诊断中的价值

目的评价免疫组织化学染色和SYT-SSX融合基因检测在滑膜肉瘤诊断中的价值与应用范围。方法收集可能为滑膜肉瘤的病例195例,根据临床表现、组织学形态和免疫组织化学染色结果将其分成确诊、高度可疑和可疑滑膜肉瘤,利用逆转录一聚合酶链反应（RT-PCR）技术检测石蜡包埋组织中SYT-SSX融合基因的表达,并比较其与免疫组织化学PV6000二步法染色之间的关系,评价各自的诊断价值。结果确诊、高度可疑和可疑滑膜肉瘤分别为62（31．8％）、49（25．1％）和84例（43．1％）。179例（91．8％）样本能够进行SYT-SSX的RT-PCR检测,其中140例（78．2％）呈阳性。SYT-SSX在确诊、高度可疑和可疑病例中的阳性率分别为94．7％（54／57）、86．0％（37／43）和62．0％（49／79）。上皮膜抗原（EMA）在确诊和高度可疑滑膜肉瘤SYT—SSX阳性病例中的阳性率明显高于其SYT-SSX阴性病例（分别P=0．022,P=0．010）,且EMA与SYT-SSX表达呈正相关（分别rs=0．431,P=0．001．rs=0．463,P=0．002）,而细胞角蛋白、波形蛋白和S-100蛋白在两类病例中的阳性率差异无统计学意义（P〉0．05）;4种指标在可疑滑膜肉瘤SYT-SSX阳性和阴性病例中的表达差异无统计学意义（P〉0．05）。结论利用传统诊断方法可以确诊的滑膜肉瘤不必进行SYT-SSX检测;EMA免疫组织化学染色在高度可疑滑膜肉瘤中的诊断价值与SYT—SSX的RT—PCR检测相近,可以代替后者;但是,融合基因的RT-PCR分析对可疑滑膜肉瘤的确诊具有重要意义。     

Synovial sarcoma, a primary liver tumor--a case report

An 18-year-old female presented with a mass involving the liver which was resected. Microscopically, it was diagnosed as monophasic synovial sarcoma. Cytogenetic study (FISH) revealed translocation t(X; 18), confirming the diagnosis.     

Synovial sarcoma enzyme histochemistry of a typical case

Summary A typical case of biphasic synovial sarcoma was studied using enzyme histochemistry. A marked difference between the staining characteristics of the spindle cells and the epithelial-like cells was demonstrated by reactions for various hydrolytic enzymes. The epithelial-like cells exhibited a strong reactivity for alkaline phosphatase, acid phosphatase, adenosine triphosphatase and nonspecific esterase, whereas spindle-cells were completely unreactive when tested for these enzymes.This is, to our knowledge, the first report demonstrating differences in the enzymatic pattern of the two cell populations which compose synovial sarcoma.     

Cystic synovial sarcoma of the pleura mimicking a cystic thymoma: a case report illustrating the role of decreased INI-1 expression in differential diagnosis

Less than 40 cases of primary pleural synovial sarcoma (SS) have been reported to date. Furthermore, only three cases of cystic SS have been documented in the English literature, including cases originating from sites other than the pleura. Herein, we present an exceedingly rare case of cystic SS originating from the mediastinal side of the visceral pleura in an asymptomatic 47-year-old man, which was detected during a checkup. On contrast-enhanced computed tomography, distinguishing between cystic SS and cystic thymoma was difficult because the tumor was attached to the anterior mediastinum where the latter type of malignancy is more often detected. Histopathological examination showed tumor cells with spindled morphology showing hypercellularity and moderate nuclear atypia, with less than one mitotic figure per high-power field. As these features are associated with both monophasic fibrous SS and type A thymoma, more data was required to determine proper diagnosis, and therefore, immunohistochemistry was performed. Along with a conventional panel of markers, the SS-specific marker integrase interactor 1 (INI-1) was applied and found to be decreased; decreased expression of INI-1 is characteristic of SS. A diagnosis of SS was confirmed by detection of the SYT-SSX fusion gene via fluorescence in situ hybridization. Given the relatively common availability of INI-1 testing in departments of pathology, this protein would be helpful incorporated into the standard panel of markers for diagnosing SS.     

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.

Primary sarcoma of the anterior cruciate ligament - a case report

Clear cell sarcoma of tendons and aponeuroses (CCSTA) is a rare, aggressive soft tissue malignancy, which is found in intimate association with tendon, aponeurosis or fascia. It has not previously been reported in association with intraarticular ligaments. We report the first case of an intraarticular CCSTA, in this case of the anterior cruciate ligament and describe the diagnostic and treatment challenges of intraarticular tumours of the knee.