Primary pericardial synovial sarcoma: a case report and literature review

Multimodal imaging features of primary pericardial synovial sarcoma: a case report

Background

Primary pericardial synovial sarcoma is an extremely rare malignant tumor, and affected patients have a poor prognosis. Only a few cases have been reported in the literature.

Case summary

A 34-year-old man was admitted to our hospital with chest tightness and a cough. An echocardiogram revealed a heterogeneous mass with a large pericardial effusion. Further computed tomography (CT) of the chest and cardiac magnetic resonance imaging (CMRI) demonstrated an irregular pericardial mass abutting the left atrium and left ventricle and invading the mediastinal structures. Pathology results showed that the tumor was a monophasic synovial sarcoma. The patient underwent chemotherapy and survived for 17 months.

Discussion

Many cardiac tumors are clinically asymptomatic or nonspecific, and they are frequently detected or diagnosed at an advanced stage of the disease. Multimodal cardiac imaging facilitates the detection and assessment of cardiac tumors. In particular, CMRI is considered as a superior imaging tool, because it provides high tissue contrast and can detect invasion of the myocardium. We describe the clinical details and multimodal imaging features of a rare primary pericardial synovial sarcoma, hoping to provide guidance for the diagnosis of similar cases in the future.

Primary Pericardial Synovial Sarcoma: A Case Report and Literature Review

We report a case of a 52-year-old woman who was referred to our institution with a superior vena cava syndrome and was investigated through echocardiography, CT and MRI revealing a well-defined, encapsulated pericardial mass. The pathology, correlated with the immunohistochemical analysis, concluded it was an extremely rare primary pericardial synovial sarcoma. The patient underwent surgery and chemotherapy with a 16-month disease-free survival and passed away after a contralateral aggressive relapse. Moreover, we discuss the role of each imaging modality together with their pericardial synovial sarcoma reported features.

Genetic aberrations and molecular biology of cardiac sarcoma

Cardiac tumors are rare and complex entities. Early assessment and differentiation between non-neoplastic and neoplastic masses, be they benign or malignant, is essential for guiding diagnosis, determining prognosis, and planning therapy. Cardiac sarcomas represent the most frequent primary malignant histotype. They could have manifold presentations so that the diagnosis is often belated. Moreover, considering their rarity and the limitation due to the cardiac location itself, the optimal multimodal management of patients affected by primary cardiac sarcomas still remains highly difficult and outcome dismal. Therefore, there is an urgent need to improve these results mainly focusing on more adequate tools for prompt diagnosis and exploring new and more effective therapies. Knowledge about the molecular landscape and pathogenesis of cardiac sarcoma is even more limited due to the rarity of this disease. In this sense, the molecular characterization of heart tumors could unfold potentially novel, druggable targets. In this review, we focused on genetic aberrations and molecular biology of cardiac sarcomas, collecting the scarce information available and resuming all the molecular findings discovered in each tumor subtype, with the aim to get further insights on mechanisms involved in tumor growth and to possibly highlight specific molecular profiles that can be used as diagnostic tests and unveil new clinically actionable targets in this tricky and challenging disease.

Pericardial Synovial Sarcoma: Case Report, Literature Review and Pooled Analysis

BACKGROUND

Pericardial synovial sarcomas (PSS) are very rare tumors, with dismal prognosis and limited data. We describe the clinical features and identify prognostic factors of primary PSS.

CASE REPORT

We describe the case of a 56-year-old male patient with PSS managed by the multidisciplinary team of thoracic oncology. The therapeutic plan comprised surgery, chemotherapy, stereotactic radiosurgery and targeted therapy, with excellent results.

MATERIALS AND METHODS

Data from 37 cases reported in English during the past 20 years were gathered and analyzed. PSS was found to occur at a mean age of 36±17.082 (range=13-67) years. Survival analysis was performed on 20 cases with follow-up of at least 6 months.

CONCLUSION

Only complete resection of the tumor seems to be an independent prognostic factor. To our knowledge, this is the first report on the safety and effectivity of pazopanib in PSS and may provide guidance for similar cases in the future.

Pleural malignant mesothelioma versus pleuropulmonary synovial sarcoma: a clinicopathological study of 22 cases with molecular analysis and survival data

The aim of this study was to carry out a comparative analysis by transducin-like enhancer of split 1 (TLE1) immunohistochemistry and molecular analysis of SYT-SSX, for 16 pleural predominantly sarcomatoid mesotheliomas and six cases of pleuropulmonary synovial sarcoma (five pleural in distribution only, with one case of a predominantly subpleural upper lobe synovial sarcoma), all of which were solely or predominantly monophasic. Our comparison included survival and some clinical data. We consider that the following points emerged from this study.

Primary mediastinal synovial sarcoma: A rare case report

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Synovial sarcomas commonly occur in the extremities of young adults.

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A primary occurrence in the mediastinum is very rare with only a few reported cases in the world literature.

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This paper highlights the importance of recognizing an unusual presentation of this aggressive neoplasm to aid appropriate clinical management.

Introduction

Synovial sarcomas commonly occur in the extremities of young adults. A primary occurrence in the mediastinum is very rare with only a few reported cases in the world literature.

We report a case of mediastinal synovial sarcoma. This paper is about a 47-year-old male who presented with retrosternal chest pain and shortness of breath on exertion. Imaging showed an anterior mediastinal mass. Pathological examination of the resected mass showed a biphasic neoplasm with a spindle cell component admixed with gland-like elements. The tumor showed positive staining with cytokeratin, epithelial membrane antigen and vimentin confirming the diagnosis of a biphasic synovial sarcoma.

Discussion

A wide range of neoplasms, both primary and metastatic, occur in the mediastinum, which pose considerable diagnostic difficulties. A synovial sarcoma should always be considered in the differential diagnosis, and immunohistochemistry is an important adjuvant tool in this situation.

Conclusion

This paper highlights the importance of recognizing an unusual presentation of this aggressive neoplasm to aid appropriate clinical management.

Primary pericardial synovial sarcoma

A 57-year-old man was admitted to our hospital with cardiomegaly on a chest roentgenogram. A mediastinal tumor was observed during a chest computed tomographic scan and the patient was diagnosed with pericardial synovial sarcoma as a result of a tumor biopsy. Surgery, radiotherapy and chemotherapy were carried out, and although the tumor temporarily decreased in size, it subsequently increased and the patient died approximately 3 years following the initial medical examination. Most synovial sarcomas commonly occur in the vicinity of the joints of the extremities. Therefore, we herein report a rare case of synovial sarcoma which occurred in the pericardium.

Primary pericardial synovial sarcoma in an adolescent patient: magnetic resonance and diffusion-weighted imaging features

Primary synovial sarcomas of the pericardium are extremely rare tumors, especially in pediatric population. As far as we know, only few cases have been reported in the literature. This uncommon location for synovial sarcomas could lead to misdiagnosis. Radiologists and clinicians should be aware of the imaging findings and differential diagnosis of pericardial synovial sarcoma. Herein we presented a 15-year-old boy who had primary pericardial synovial sarcoma with imaging features.

Pericardial synovial sarcoma: challenges in diagnosis and management

Introduction: Pericardial synovial sarcoma is an extremely rare tumor with poor prognosis. Timely diagnosis and aggressive multimodal management improves patient outcome. We present our experience of diagnosis and management of a young patient with monophasic synovial sarcoma arising from pericardium.

Case: A 27-year-old man presented with dyspnea and cough of three weeks duration. Examination revealed sinus tachycardia, distant heart sounds and elevated jugular venous pressure. Chest X-ray showed widened mediastinum. Transthoracic echocardiogram (TTE) noted large pericardial effusion with tamponade physiology. Therapeutic pericardiocentesis yielded hemorrhagic fluid. Computed tomography (CT) of the chest showed persistent pericardial effusion and a left anterior mediastinal mass. Left anterior thoracotomy, pericardial window and left anterior mediastinotomy were done, revealing a well-encapsulated gelatinous tumor originating from the pericardium. Histology and immunohistochemical profile showed the tumor to be a monophasic synovial sarcoma. Fluorescent in-situ hybridization (FISH) was positive for SS18 (SYT) gene rearrangement on chromosome 18q11, substantiating the diagnosis. Work-up for metastases was negative. Neo-adjuvant chemotherapy with high dose ifosfamide led to substantial reduction in the size of the tumor. The patient underwent surgical resection and external beam radiation therapy (EBRT) post surgery. He had symptom-free survival for 8 months prior to local recurrence. This was managed with left lung upper lobectomy and follow-up chemotherapy with docetaxel. The patient is currently stable with an acceptable functional status.

Conclusion: In patients with pericardial effusions of unknown etiology, multiple modalities of cardiac imaging must be employed if there is suspicion of a pericardial mass. CT and magnetic resonance imaging (MRI) are useful to evaluate for pericardial thickening or masses in addition to TTE. Treatment of synovial sarcoma is not well established. Surgery is the cornerstone of treatment. In non-resectable tumors, aggressive neo-adjuvant chemotherapy with ifosfamide followed by surgical resection and EBRT may lead to improved outcome.

Primary pericardial synovial sarcoma: A case report and literature review

Primary pericardial synovial sarcoma is extremely rare, with few published cases in the literature. We report the case of an adolescent aged 13 years with primary pericardial synovial sarcoma discovered during tamponade, confirmed by molecular biology, and for whom treatment combined radiosurgery and adjuvant chemotherapy. The particularity of the case we are reporting stems from the young age of our patient (13 years) as well as the duration of remission, which is quite long (21 months) prior to a superior mediastinal relapse compared to cases reported in the literature. <Learning objective: Synovial sarcoma is difficult to diagnose and has a poor prognosis. Here, a 13-year-old diagnosed with primary pericardial synovial sarcoma was treated with combined radiosurgery and adjuvant chemotherapy leading to continuous remission for 21 months. This regimen could be used to successfully manage future patients. Molecular biology is useful in the diagnosis of synovial sarcoma through the identification of t(X;18) translocation in atypical locations as in the present case.>.

Primary cardiac synovial sarcoma

Primary cardiac synovial sarcoma is an extremely rare entity. The clinical and pathologic characteristics are still poorly understood, and prognostic factors influencing overall survival are still unknown. In the present study, all characteristics of reported patients, including sex, age, clinical presentations, laboratory tests, electrocardiogram, imaging findings, pathology, location, therapy, and follow-up were carefully reviewed and survival analysis was performed. The present study has summarized some key features and may provide an effective consultation for the diagnosis and treatment of the tumor.

Pericardial synovial sarcoma in a dyspnoeic female with tuberculous pericarditis: A case report

Synovial sarcomas of the pericardium are extremely rare and associated with poor survival rate. The current case report describes a 45-year-old female who presented with dyspnea upon exertion, a paroxysmal cough, night sweats and recurrent pericardial effusion. The patient was diagnosed with tuberculous pericarditis and received antituberculous drug therapy. Echocardiography and magnetic resonance imaging (MRI) revealed a pericardial mass lying predominantly over the right atrium. The patient was treated by surgical excision and a subsequent histological analysis confirmed the diagnosis of a pericardial synovial sarcoma. Under high power examination, a characteristic biphasic appearance consisting of hypercellular spindled cell sheets was observed. Immunohistochemistry demonstrated positive staining for epithelial membrane antigen (EMA), vimentin and Bcl 2. The patient was then referred for adjuvant chemotherapy with a combination of adriamycin and ifosfamide. The patient has since remained clinically free of disease for 32 months.

Primary cardiac synovial sarcoma

Primary cardiac synovial sarcoma is an uncommon malignant neoplasm, with only a handful of cases reported in the English literature to date. Synovial sarcomas have also been described at other unusual sites, such as the heart, pleuropulmonary region, kidney, prostate, liver, mediastinum, retroperitoneum, gastrointestinal tract, and peripheral nerve. For synovial sarcomas that arise at these unusual locations, definitive diagnosis is challenging and requires use of ancillary diagnostic procedures, such as immunohistochemistry, electron microscopy, and molecular genetic techniques, for confirmation of diagnosis. The nonrandom occurrence of t(X;18) has been found consistently in synovial sarcomas. It has also been found as a sole cytogenetic abnormality in some cases, suggesting it as a key molecular event in tumor development. This review highlights salient features of primary cardiac synovial sarcoma and the associated diagnostic challenges.

Pericardial synovial sarcoma, a potential for misdiagnosis: clinicopathologic and molecular cytogenetic analysis of three cases with literature review

Synovial sarcomas arising in unexpected locations may lead to diagnostic challenges. In this report, we describe 3 cases of synovial sarcoma that manifested clinically as primary pericardial lesions. All 3 cases occurred in men in their fourth decade. Fever, cough, chest pain, and chest distress were the most common symptoms. Histologically, 2 of the tumors were spindle cell monophasic, and 1 tumor was biphasic. By immunohistochemical studies, the tumor cells were positive for cytokeratins and epithelial membrane antigen. In addition, the tumor cells displayed focal immunoreactivity for calretinin, cytokeratin 5/6, and HBME-1, resulting in the initial interpretations of malignant mesotheliomas. None of the 3 cases were diagnosed correctly until subsequent molecular cytogenetic assays demonstrated the presence of SYT gene rearrangements. As there are overlapping morphologic features between pericardial synovial sarcoma and mesothelioma, molecular analysis is essential for differential diagnoses.

Primary cardiac synovial sarcoma: a case report and brief review of the literature

Synovial sarcoma comprises approximately 10% of all soft tissue sarcoma diagnoses; a primary synovial sarcoma of the myocardium is exceedingly rare. There have been very few cases reported in the literature thus far. With the identification of the characteristic and diagnostic chromosomal abnormality t(X;18), this may become an increasingly recognized entity. Our report adds to the limited published cases of primary cardiac synovial sarcoma with the characteristic t(X;18). Further elucidation of the effects of this translocation on the cell cycle may lead to directed therapies in the future.

Primary mediastinal synovial sarcoma: a case report and review of the literature

Primary mediastinal synovial sarcoma is a rare malignancy with only a few cases reported so far. A 56-year-old woman was admitted to our hospital for an investigation of a nodule in the left middle lung on chest radiography. Computed tomography revealed a mediastinal mass first described as a solitary fibrous tumor. The diagnosis of synovial sarcoma was established by computed tomography-guided percutaneous needle biopsy. Work up showed no metastasis to distant organs or contralateral pleural cavity. The mass was surgically resected; pathological and immunohistochemical analyses confirmed the diagnosis of a monophasic spindle cell synovial sarcoma probably originating from phrenic nerve. The patient received adjuvant chemotherapy and radiation and is free of recurrence after a follow up of 16 months.

Primary cardiac sarcomas: a clinicopathologic analysis of a series with follow-up information in 17 patients and emphasis on long-term survival

Although cardiac sarcomas are rare in comparison to their soft tissue counterparts, they are the second most common type of primary cardiac neoplasm. Of the few hundred cases reported, most has been based on autopsy series. A series of 27 cardiac sarcomas removed at surgery for curative and diagnostic intent were reviewed for clinicopathologic features with correlation to available postoperative follow-up data in 17 patients. There were 6 angiosarcomas, 6 myxofibrosarcomas, 3 malignant peripheral nerve sheath tumors, 3 leiomyosarcomas, 2 synovial sarcomas, 1 epithelioid hemangioendothelioma, 1 chondrosarcoma, 1 osteosarcoma, and 4 poorly differentiated sarcomas. There was a wide age and size range with slight female predilection. There were 20 cases that arose in the atria/pulmonary vessels, 4 in the ventricles, 1 in mitral valve, and 2 in epi/pericardium. There was a slight left predilection. The histologic grade was low in 4, moderate in 3, and high in 20 cases. Six high-grade and 1 low-grade tumors were also treated with adjuvant chemotherapy and/or radiation. In 17 patients with follow-up data, 6 of 12 patients with high-grade tumor died (4 within 5 days of the initial surgery, 1 in 21 months, and 1 in 131 months), and 1 patient with moderate-grade tumor and all 4 patients with low-grade tumor were alive without evidence of disease at the end of follow-up. Tumor grade appeared to be prognostically important in cardiac sarcoma. Long survival was achieved in patients who survived the initial surgery well.

Primary pericardial synovial sarcoma confirmed by molecular genetic studies: a case report

Primary pericardial synovial sarcoma is an extremely rare tumor. The awkward tumor site and clinical features associated with quite advanced disease at presentation make obtaining adequate biopsy material challenging. Ambiguous histologic features may also make diagnosis difficult. We present a case of a 15-year-old patient with an original diagnosis of a spindle cell thymoma. After definitive surgery the diagnosis was amended to a primary pericardial synovial sarcoma. Molecular confirmation of the SYT-SSX fusion gene was critical in reaching an accurate diagnosis. This highlights the necessity for routine molecular genetic studies, so that patient therapy can be directed accordingly.

Primary synovial sarcoma of the heart: a cytogenetic and molecular genetic analysis combining RT-PCR and COBRA-FISH of a case with a complex karyotype

Synovial sarcomas usually occur in the soft tissues of the extremities of adolescents and middle-aged patients, in the vicinity of large joints. We present a patient with a synovial sarcoma of the left atrium and ventricle, which is an extremely rare location. Diagnosis was confirmed by reverse transcriptase polymerase chain reaction (RT-PCR), showing the t(X;18) fusion transcript. With a multicolor COmbined Binary RAtio labeling Fluorescence In Situ Hybridization (COBRA-FISH) technique, a complex karyotype evolved with identification of derivative chromosomes with multiplex rearrangements. This underscores the importance of molecular analysis of spindle cell tumors in unusual locations. Moreover, it shows that the presumed diagnostic translocation t(X;18) can be embedded in a sequence of other chromosomal rearrangements of which the function is as yet unknown.

Pericardial synovial sarcoma: 14-year survival with multimodality therapy

We report a case of recurrent primary synovial sarcoma of the pericardium. Reverse transcriptase-polymerase chain reaction analysis for t(X,18) demonstrated the presence of the chimeric transcript SYT/SSX. Because of the rarity of this entity, optimal therapy is unknown. The prognosis of this tumor is very poor in previous reports. In this report, we present a case with five recurrences treated by a combination of surgery, chemotherapy, and radiotherapy. The patient survives now for more than 14 years, the longest reported survival of a primary synovial sarcoma of the pericardium.

SYT–SSX fusion genes in synovial sarcoma of the thorax

Synovial sarcoma (SS) is characterized by a chromosomal translocation resulting in the expression of an SYT-SSX chimeric transcript, usually SYT-SSX1 or SYT-SSX2. Synovial sarcoma typically originates in the limbs, and its location in the thorax is rare. Synovial sarcomas are usually classified into three histologic subtypes: biphasic, monophasic and poorly differentiated tumors. The detection of the characteristic chimeric transcript often contributes to a histopathological diagnosis, especially when the tumor arises in an unusual location. Previous studies have shown that SYT-SSX1 is the most common SYT-SSX fusion transcript in biphasic synovial sarcomas of the limbs. Here, we report two cases of synovial sarcoma originating in the thorax. The presence of SYT-SSX2 chimeric transcripts was confirmed by reverse transcript polymerase chain reaction (RT-PCR) and a direct sequencing analysis in both cases. The tumor in case 1 originated from the pericardium, which is an exceedingly rare site for primary synovial sarcoma; only three other cases of synovial sarcoma originating in the pericardium have been previously reported. Case 2 exhibited a biphasic synovial sarcoma of the mediastinum containing an SYT-SSX2 fusion transcript, which is a rare fusion type in biphasic synovial sarcomas of the limbs. We reviewed previous reports of thoracic synovial sarcomas containing an analysis of the SYT-SSX fusion transcript and found that case 2 in the present study was the first description of a biphasic synovial sarcoma of the thorax with an SYT-SSX2 fusion transcript. However, the number of reported cases was not sufficient to conclude that SYT-SSX2 fusion in biphasic synovial sarcoma of the thorax is, indeed, rare. Further genetic analysis is needed to fully understand the biological and clinical features of synovial sarcoma originating in the thorax.

[Primary renal synovial sarcoma. A new entity in the morphological spectrum of spindle cell renal tumors]

We report 2 primary renal synovial sarcoma. These tumors were formerly designated as embryonal cystic sarcoma of the kidney. Most cases are diagnosed between the ages of 20 and 50 years. Some cases show local recurrence after nephrectomy. On gross examination, tumors are large, partially necrotic, and usually contain cysts. Microscopically, tumors are characterized by monomorphic plump spindle cells. The cysts are lined by mitotically inactive epithelial cells without striking cellular atypia. The spindle cells were immunoreactive for EMA, CD56, and sometimes for CD99. They were non-reactive for desmin, actin, S 100, and cytokeratins. The cyst epithelium is cytokeratin positive. The presence of a SYT-SSX gene fusion resulting from the t(X;18) characteristic for synovial sarcoma was demonstrated by reverse transcriptase polymerase chain reaction in both tumors. Primary renal synovial sarcoma is a distinctive tumor entity, which should be considered in renal tumors consisting of spindle cells.

Echocardiographic and pathologic characteristics of primary cardiac tumors: a study of 149 cases

To investigate the characteristics and pathological features of primary cardiac tumors and to evaluate the diagnostic sensitivity of echocardiography in primary cardiac tumors, all pathologic and echocardiographic records at the Chinese PLA general hospital and its satellite hospitals between January 1st, 1990 and January 1st, 2000 were reviewed to identify patients with a confirmed diagnosis of primary cardiac tumors. A total of 149 patients who had complete echocardiographic records and who were diagnosed with primary cardiac tumors were included in the study. Pathologic and echocardiographic records were reviewed retrospectively to evaluate the presence, location and histologic type of the tumors. The majority (n=118, 79.2%) of cases had been diagnosed with benign tumors. Myxoma was the most common histologic type accounting for 50.0% of total cardiac tumors. Lipoma was the second most common type of benign tumor. Among cases with malignant tumors (n=31, 20.8%), unclassified sarcoma (n=7), angiosarcoma (n=6) and rhabdomyosarcoma (n=6) were the common histologic types of primary malignant tumor. Non-myxomatous benign tumors were more likely to have occurred in the ventricle than myxomas (17/43, 39.5% vs. 7/75, 9.3%; P=0.00). The proportion of pericardium involvement in the malignant tumors (8/31, 25.8%) was significantly higher than that in the myxomas (0/75, 0%; P=0.00) and non-myxomas (2/43, 4.7%; P=0.01). The diagnostic sensitivity of transthoracic and transesophageal echocardiography was 93.3% (139/149) and 96.8% (30/31), respectively. The study, using a relatively large sample, confirms that myxoma was the most common primary cardiac tumor. The locations of tumor involvement varied by types of tumor. Echocardiography may be a useful tool for early diagnosis of primary cardiac tumors.

Incidental localized (solitary) epithelial mesothelioma of the pericardium: case report and literature review

Primary mesotheliomas of the pericardium are rare tumors. They may occur in diffuse, multiple, and localized forms. Most of the pericardial mesotheliomas are multiple or diffuse growths encasing the heart, localized forms being distinctly uncommon. We report a localized mesothelioma of the pericardium found incidentally at the autopsy of a 76-year-old woman. The neoplasm measured 3.6 x 2.4 x 2.5 cm., was well circumscribed, and affected the entire thickness of the myocardium extending from the epicardium to the endocardium of the anterior wall of the right ventricle. The tumor was epithelial in type, showed an immunohistochemical profile compatible with mesothelioma, and was DNA aneuploid. A review of the literature yielded four cases of localized pericardial mesothelioma, including the present. Most cases are seen in women and are of the epithelial variant. There is a wide age range at presentation. Localized mesotheliomas are capable of aggressive behavior. Nevertheless, in contrast to diffuse tumors, complete surgical excision may be curative. Differential diagnosis includes solitary fibrous tumor, synovial sarcoma, epithelioid angiosarcoma, and adenomatoid tumor of the pericardium.

Primary synovial sarcoma of the kidney: a case report with literature review

We describe a case of primary renal synovial sarcoma (SS) in a 48-year-old man. The patient presented with hematuria and was found to have a large tumor in his left kidney on computed tomography scan. Histology revealed a highly cellular spindle cell neoplasm with minimal pleomorphism. The major differential diagnoses included leiomyosarcoma, hemangiopericytoma, and SS. The presence of focal areas with a biphasic pattern, uniformly positive immunostain for bcl-2, focally positive immunostains for epithelial membrane antigen and cytokeratin, and negative immunostains for CD-34, smooth muscle actin and S-100 established the diagnosis. This was subsequently confirmed by molecular testing for t(X;18) translocation. Since the existence of primary SS in the kidney was first suggested in 1999, to the best of our knowledge a total of 19 cases including the present case have been reported to date. Although primary renal SS is rare, these findings indicate that it should be included in the differential diagnosis of spindle cell tumors of the kidney.

Primary synovial sarcoma of the kidney

The authors present two cases of primary synovial sarcoma of the kidney. Both patients had a mass in the upper part of the right kidney without any primary extrarenal neoplastic lesions. Grossly, the tumors were soft to rubbery masses measuring 5.5 cm and 5 cm in diameter, respectively. Histologically, both tumors were poorly differentiated synovial sarcoma. The lesions exhibited a hypercellular solid or lobular growth of round, oval, or short spindle cells in variably solid sheets, in intersecting fascicles, or in a haphazard fashion. Areas of solid aggregation or fascicles of the tumor cells alternating with hypocellular myxoid tissues, together with areas displaying a prominent hemangiopericytoma-like pattern, were found. Immunohistochemically, vimentin was diffusely positive and a few tumor cells were positive for cytokeratin, epithelial membrane antigen, and neurofilament. The tumor cells were negative for S- 100 protein, CD34, smooth muscle actin, and desmin, whereas CD56 and CD99 were positive. In both cases, reverse transcription-polymerase chain reaction using ribonucleic acid extracted from formalin-fixed, paraffin-embedded tissues detected SYT-SSX2 fusion gene transcripts, which are characteristic molecular findings of synovial sarcoma. One patient died 10 months after diagnosis. These tumors are unique cases of primary synovial sarcoma of the kidney confirmed by molecular study.

Synovial neoformations and tumours

An important group of soft tissue tumours and tumour-like lesions originates from the synovium of the joints, bursae and tendon sheaths. These include synovial chondromatosis, diffuse articular lipomatosis (lipoma arborescens), villonodular synovitis, synovial haemangioma, synovial chondroma and fibroma (intracapsular and peri-articular), primary chondrosarcoma originating from the synovium and synovial sarcoma. The main clinical symptoms of these tumours, such as pain, swelling, effusion and joint locking, are not specific, so the diagnosis can easily be missed in clinical practice. The most important clinical characteristics and the differential diagnostic clues for synovial tumours and tumour-like lesions are described in this chapter. In addition, the new results of genetic and histological studies are discussed, together with a summary of the available evidence-base for therapy.

Molecularly confirmed primary prostatic synovial sarcoma

We report the second molecularly-confirmed primary prostatic synovial sarcoma. The diagnosis was particularly elusive at the light microscopic level in that the tumor failed to show epithelial differentiation, but it did show combined spindle-cell and poorly differentiated (round-cell) morphologies. The immunohistochemical staining profile was nonspecific and potentially misleading. Only by demonstration of the characteristic SYT-SSX gene fusion of synovial sarcoma by reverse transcriptase polymerase chain reaction (RT-PCR) analysis of RNA extracted from archival material could the diagnosis be confirmed. This case further illustrates the use of this technique in diagnostic pathology.