Synovial sarcoma of the prostate with t(X;18)(p11.2;q11.2)

Prostate stromal sarcoma mimicking benign prostate hyperplasia: A case report

INTRODUCTION & OBJECTIVES

Prostate stromal sarcoma is extremely rare and aggressive malignancy accounting for less than 1 % of all type of prostate cancers. It is frequently misdiagnosed from other lower urinary tract symptoms (LUTS) problems.

CASE PRESENTATION

We present a case report of 45-year-old male complaining with LUTS problems. Patient also suffers anorexia and weight loss. He was first diagnosed with benign prostate hyperplasia (BPH). Patients had done transurethral resection of prostate (TURP) to alleviate the complaint, but the symptoms worsened and recurred. Histopathological examination findings confirmed prostate stromal sarcoma (T4N0M0). Patient was further examined using MRI and then radical prostatectomy procedure was performed.

DISCUSSION

Incidence of prostate stromal sarcoma is very low and most commonly presents with obstructive LUTS symptoms. This could mimic other disease such as BPH or other type of prostate cancer. Therefore, clinicians require a high suspicion in patient with recurrent LUTS.

CONCLUSION

Prostate stromal sarcoma diagnosis is a challenging disease entity that necessitates histopathology examination. Timely and accurate diagnosis of prostate stromal sarcoma is needed to achieve better outcome and prognosis for the patients.

Unusual Cause of Acute Urinary Retention in Young Male Patient: Primary Synovial Sarcoma of Prostate—A Case Report

Introduction  Primary synovial sarcoma (SS) of the prostate is the rarest variety of prostate sarcoma. The first documented and confirmed case of SS of the prostate was published by Iwasaki et al in the year 1999; since then, only a few cases of primary SS of the prostate have been published in English literature.

Case Report  We report a unique case of primary SS in a young patient who presented with acute urinary retention and underwent emergency suprapubic catheterization, and on evaluation was diagnosed with primary SS of the prostate. Patient was managed with radical cystoprostatectomy and resection of the anterior wall of rectum infiltrated by the tumor with bilateral pelvic lymph node dissection and adjuvant chemotherapy. Patient died after 2 months of surgery.

Conclusion  Primary SS of the prostate is a rare disease and important clinical entity to be included in differential diagnosis of acute urinary retention in young patients. It is associated with high local recurrence and poor prognosis, which warrants multidisciplinary approach of treatment.

Primary prostate synovial sarcoma: A case report and review of literature

Prostate synovial sarcoma (SS) is extremely rare. We report a case of prostate SS diagnosed using fine-needle biopsy. The following findings were found: The serum prostate specific antigen level was low, magnetic resonance imaging shows an irregular soft tissue mass in the right posterior part of the prostate, and computed tomography examinations did not reveal any tumor at other parts of the body. Microscopy showed that the tumor cell morphology was densely arranged by interwoven short strands of deep-stained nuclear spindle cells. Immunohistochemical tests were positive for SS18-SSX and SSX. Molecular testing showed that SS18 break-apart Fluorescence In Situ Hybridization (FISH) results were positive, and a comprehensive analysis of this case was performed. Nine cases of prostate SS reported in the English literature were reviewed. In addition, the differential diagnosis, clinical treatment, and clinical prognosis of prostate SS are comprehensively described.

Primary cardiac synovial sarcoma: a clinicopathological, immunohistochemical, and molecular genetics study of five clinical cases

BACKGROUND

Primary cardiac synovial sarcoma was an exceedingly rare tumor that less reported. The study investigated the clinicopathologic, immunohistochemical, and molecular features of primary cardiac synovial sarcoma.

METHODS

A total of five cardiac synovial sarcoma cases were assessed and reviewed using H&E, immunohistochemical and fluorescence in situ hybridization staining methods. Clinicopathological data were retrospectively analyzed and followed up.

RESULTS

The cases occurred in four males and one female ranging in age from 23 to 48 years (mean, 32 years). The tumors were grossly large and solid (7.4-13.7 cm; mean 8.6 cm). Microscopically, clinical cases were biphasic (n = 2) and monophasic (n = 3) types and were diffusely immunoreactive for EMA, vimentin, and BCL-2. All cases demonstrated SS18 rearrangement by fluorescence in situ hybridization staining. Clinically, three patients died within 1 year after surgery, while one patient had bone metastasis and still carried the disease. One last patient underwent a heart transplant and survived without evidence of the disease.

CONCLUSION

Cardiac synovial sarcoma was an aggressive tumor whose differentiation may be a continuous and complex morphologic spectrum. SS18 rearrangement demonstration by fluorescence in situ hybridization was decisive in our study for differential diagnosis of cardiac synovial sarcoma and other tumors. Cardiac synovial sarcoma usually endured poor survival rates. Patients in advanced stages may undergo heart transplantation as a means of improving their survival rates.

Primary Intraosseous Synovial Sarcoma with Molecular Confirmation: Expanding and Clarifying the Spectrum of This Rare Neoplasm

Synovial sarcoma is a well-known malignant tumor usually originating within deep soft tissues of the lower extremities of adolescents and young adults. Rare radiologically confirmed examples of primary bone synovial sarcoma have been documented, generally in isolated case reports. Herein, we report two cases of primary intraosseous synovial sarcoma, with molecular confirmation, involving the left humerus of a 45-year-old female and the right fourth metatarsal bone in a 36-year-old male. Additionally, we clarify the spectrum of primary intraosseous synovial sarcoma by separately analyzing reported cases with radiographic confirmation of bone origin and molecular support for the diagnosis. There are clinicopathologic differences between those tumors with documented molecular confirmation and those lacking such confirmation, specifically regarding their anatomic distribution (p < 0.0001). Regarding the radiology of our two cases, the humeral lesion appeared almost entirely intramedullary without soft tissue extension; the midfoot lesion demonstrated a destructive, metatarsal-centered bone lesion, initially thought clinically to represent primary bone osteosarcoma. The diagnoses of monophasic synovial sarcoma were rendered via core needle biopsies, with molecular FISH confirmation of SYT gene rearrangement. Clinical follow-up data was only available for the female patient with the primary humeral lesion, who underwent surgical resection, with no local recurrence or distant metastasis at 7 months postsurgery. To our knowledge, these are the first reported examples of molecularly confirmed, primary intraosseous synovial sarcomas of the humerus and metatarsal bones. Primary intraosseous synovial sarcomas with molecular confirmation differ clinically from those lacking it; however, the demographic features and metastatic potential appear similar to primary soft tissue synovial sarcoma.

Demographics, stage distribution, and relative roles of surgery and radiotherapy on survival of persons with primary prostate sarcomas

Background

Primary prostate sarcomas (PPS) are rare. Outcomes for this cancer have not been well characterized.

Materials and Methods

Subjects with a PPS diagnosed between 1973 and 2014 were identified in the SEER database. Subjects were stratified by disease stage and types of therapies received. Disease‐specific survival (DSS) and Overall survival (OS) was estimated by Kaplan‐Meier analysis and cohorts were compared with a univariate and multivariable Cox regression.

Results

The incidence of PPS among all prostate cancer diagnoses was 0.02%. Subjects younger than age 26 years at diagnosis represented 29% of cases, and 32% of primary prostate sarcomas were rhabdomyosarcoma histology.

Rhabdomyosarcoma Histologies

The median age at diagnosis was 9 years. Between age 0‐25 years rhabdomyosarcoma accounted for 96.4% of primary prostate sarcoma diagnoses, after age 25 rhabdomyosarcoma represented 15% of new diagnoses. The 10‐year DSS and OS for rhabdomyosarcoma was 47% and 44%.

Non‐Rhabdomyosarcoma Histologies

The median age at diagnosis was 71 years. The most common diagnoses were leiomyosarcoma (33%) and carcinosarcoma (28%). Localized, regional, or distant disease occurred in 40%, 34%, and 26% of cases. The 10‐year DSS and OS were 26% and 14%. In locally advanced cases, RT added to surgery trended toward improved DSS (P = 0.10).

Conclusions

Disease‐specific survival and OS for non‐rhabdomyosarcoma histologies appear inferior to those of rhabdomyosarcoma. The addition of RT to surgical resection may improve DSS in locally advanced non‐rhabdomyosarcoma. This is the largest report of the incidence, stage distribution, and survival for this extremely rare urologic malignancy providing valuable prognostic information.

Primary Intraprostatic Synovial Sarcoma

Primary intraprostatic synovial sarcoma is a rare presentation of an otherwise well-studied disease, and it is one of the few primary sarcomas to occur in the prostate. Ancillary diagnostic techniques including immunohistochemistry and molecular genetics are useful to establish a definitive diagnosis. Despite its unorthodox location, it shares histologic and molecular genetic characteristics with tumors found elsewhere in the body. Most notably, the chromosomal translocation t(X;18)(p11;q11) encodes a chimeric transcription-activating protein, SS18-SSX, which has been identified as the primary driver mutation. The SS18-SSX fusion gene provides a consistent and dependable means of establishing a definitive diagnosis via reverse transcription-polymerase chain reaction or fluorescence in situ hybridization. Recent studies have continued to provide insight into the oncogenesis of this disease. The goal of this review is to elaborate on the clinicopathologic characteristics and underline those techniques that best facilitate the diagnosis of primary intraprostatic synovial sarcoma.

Monophasic Synovial Sarcoma of Prostatic Fascia: Case Report and Literature Review

Synovial sarcoma (SS) primarily occurs in the para-articular soft tissue of the lower extremities in young adults and it is extremely rare in the prostatic region. We report a case of a 46-year-old man who presented with urinary retention. Pelvic ultrasound (US) examination, computed tomography (CT), and magnetic resonance imaging (MRI) demonstrated an 8.5 cm mass that appeared to originate in the prostatic fascia of the right lobe. Preoperative prostatic ultrasound transrectal needle biopsy revealed mesenchymal neoplastic tissue. Patient underwent surgery. The final pathologic findings were consistent with the diagnosis of monophasic synovial sarcoma.

Primary synovial sarcoma of the prostate metastatic to the liver and lung: a case report

Primary synovial sarcoma of the prostate is an uncommon malignant tumor. There are few cases reported in the English medical literature to date. Here, we present a case of 22-year-old man with primary synovial sarcoma of the prostate metastatic to the liver and lung. To our knowledge, only six reports of synovial sarcoma involving the prostate have been previously published. We also reviewed the previous treatments and prognoses in previous case reports and evaluate the proper treatment for this disease.

Synovial sarcoma of the kidney in a young patient with a review of the literature

Synovial sarcoma (SS) is a soft tissue, generally deep seated neoplasms that occurs generally in the proximity of large joints. We report of a case of a 33-year-old man who was diagnosed with primary SS of the kidney which is an extremely rare tumor that accounts for less than 2% of malignant renal tumors. Contemporary management of renal synovial sarcoma includes surgical resection and ifosfamide-based chemotherapy and they remain the mainstay of therapy of synovial sarcoma, which is often applied, combined as part of an aggressive treatment approach. Fewer than 50 patients have been described in the English literature. Physicians should be aware of the possibility of malignancy in cystic renal masses and raise the suspicion of synovial sarcoma, especially when patients with renal masses are young adults. Along with the case report a literature review on primary synovial sarcomas of the kidney is provided with focus on the renal tumors' differential diagnosis.

Non-epithelial neoplasms of the prostate

Non-epithelial prostatic neoplasms are infrequent and cover a broad array of entities that include both benign and highly aggressive tumours. Because they are very infrequent, there is often limited understanding of them, and the recognition of these entities, when encountered, may pose a diagnostic challenge, owing to histological overlap between them or their rarity. Most lesions in this category are mesenchymal in origin, such as prostatic stromal tumours arising from specialized prostatic stroma, smooth muscle tumours, both benign and malignant, and solitary fibrous tumours. Less commonly occurring tumours include neural, germ cell and melanocytic tumours that may be derived from cells not normally present in the prostate. Some tumours have well-established extraprostatic counterparts and, when encountered, are more commonly extraprostatic/secondary in origin; these include gastrointestinal stromal tumours and most haematopoietic tumours. The majority of tumours are characterized by a spindle cell pattern with significant overlap in morphological features. In this setting, appropriate use of immunohistochemistry and molecular studies are often necessary for accurate diagnosis, prognosis, or prediction for therapy. This review addresses and updates the clinicopathological features of the entire spectrum of non-epithelial tumours with an approach to the histological diagnosis.

Spindle-cell carcinoma of the prostate

Sarcoma of the prostate and sarcomatoid carcinoma of the prostate are rare conditions, both characterized by a poor prognosis. Sarcomatoid carcinoma of the prostate typically arises from the evolution of an underlying adenocarcinoma, occasionally featuring heterologous elements, bulky disease being possible but rare. In contrast, sarcoma of the prostate derives from non-epithelial mesenchymal components of the prostatic stroma, shows rapid growth, and frequently presents as massive pelvic tumors obstructing the urinary tract at the time of diagnosis. We report the case of a 55-year-old patient with a two-month history of symptoms of urinary obstruction. The patient presented with an extremely enlarged heterogeneous prostate, although his prostate-specific antigen level was low. The lack of a history of prostatic neoplasia led us to suspect sarcoma, and a transrectal prostate biopsy was carried out. An immunohistochemical study of the biopsy specimen did not confirm the clinical suspicion. However, in view of the clinical features, we believe that sarcoma of the prostate was the most likely diagnosis. The patient received neoadjuvant chemotherapy followed by radiation therapy. At this writing, surgical resection had yet to be scheduled.

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.

Management of monophasic synovial sarcoma of the small intestine

Although prognosis for patients with intraabdominal synovial sarcoma is poor, laparoscopic wide regional excision may allow for a more prolonged disease-free survival.

Background:

Reports of primary intraabdominal synovial sarcomas are extremely rare.

Methods:

A literature review using PubMed was performed. A retrospective review of the one known case at our institution was completed.

Results:

Even the most experienced pathologists report that synovial sarcomas can be very difficult to diagnose correctly. One cytogenic abnormality that is common (>90%) and pathognomonic for synovial sarcoma is a characteristic chromosomal translocation resulting in the SYT/SSX fusion gene. Wide regional excision has been performed for intraabdominal sarcoma, with improved results. Our patient is more than 24 months with no evidence of recurrent or metastatic disease.

Conclusions:

The prognosis for patients with intraabdominal synovial sarcoma remains poor. However, wide regional excision may allow for prolonged disease-free survival.

Primary renal synovial sarcoma

Synovial sarcomas are generally deep-seated tumors that most often occur in the proximity of large joints of adolescents and young adults. We describe two cases of primary renal synovial sarcoma that were treated successfully by radical nephrectomy. Synovial sarcoma originating from the kidney is extremely rare and the histogenesis is uncertain. Surgical resection and ifosfamide based chemotherapy are the mainstay for the management of renal synovial sarcoma. Fewer than 40 patients have been described in the English literature. Physicians should be aware of the possibility of malignancy in cystic renal masses and raise the suspicion of synovial sarcoma, especially when patients with renal masses are a young adult.

Diagnostic utility of dual-color break-apart chromogenic in situ hybridization for the detection of rearranged SS18 in formalin-fixed, paraffin-embedded synovial sarcoma

Pathological diagnosis of synovial sarcoma is often problematic due to its broad spectrum of histology. Because synovial sarcoma consistently carries a specific chromosomal translocation, t(X;18), and its derivative chimeric gene, either SS18-SSX1 or SS18-SSX2, detecting these abnormalities by reverse transcription polymerase chain reaction or fluorescence in situ hybridization has been recognized as a powerful aid for diagnosis. Recently, chromogenic in situ hybridization, which enables simultaneous visualization of both genomic abnormality and the morphology of tumor cells, has gained attention. This study investigated the diagnostic utility of dual-color break-apart chromogenic in situ hybridization as a novel method for detecting SS18 rearrangement in synovial sarcoma. Formalin-fixed, paraffin-embedded tissue samples from 16 cases of synovial sarcoma and 10 cases of 5 other types of soft tissue sarcoma were collected. Dual-color break-apart probes were designed against the genomic region adjacent to SS18. Fluorescence and chromogenic in situ hybridization studies were performed using the same sections. In both assays, the number of signals was counted for sixty nuclei per sample. Scoring ratios (unpaired signals/paired signals) were calculated. Subsequently, SS18-SSX1 and SS18-SSX2 were examined by reverse transcription polymerase chain reaction. The results of chromogenic in situ hybridization, fluorescence in situ hybridization, and reverse transcription polymerase chain reaction were correlated. Unpaired signals were clearly observed in all the synovial sarcoma samples, which mostly indicated rearranged SS18. Synovial sarcoma and non-synovial sarcoma samples were clearly distinguished from each other by the scoring ratios. Reverse transcription polymerase chain reaction demonstrated SS18 chimeric gene transcripts in all the synovial sarcoma cases, while no fusion genes were detected in the non-synovial sarcoma cases. Taken together, unpaired signals in synovial sarcoma reflected rearranged SS18. The present chromogenic in situ hybridization-based SS18 rearrangement detection system provides a highly sensitive and specific method for the diagnosis of synovial sarcoma. Chromogenic in situ hybridization-based methods have great potential for routine use in the diagnosis of synovial sarcoma.

Synovial sarcoma of the head and neck: rare case of cervical metastasis

BACKGROUND

Synovial sarcoma is a rarely encountered soft tissue sarcoma. Surgery with a wide surgical margin is the treatment of choice. However, there is no consensus on the treatment of head and neck synovial sarcoma in patients with cervical metastasis.

METHODS

A 20-year-old man was seen with a palpable mass in the right neck. He had been diagnosed with synovial sarcoma of the right tonsil and treated by surgery 1 and a half years before; therefore, the mass detected was thought to be a cervical metastasis of synovial sarcoma. We performed a modified radical neck dissection with no postoperative treatment. The pathological diagnosis was confirmed by detecting the SS-specific fusion gene SYT-SSX1.

RESULTS

The patient remains free of recurrence or metastasis 2 years and 10 months after the surgery.

CONCLUSIONS

We encountered a case of head and neck synovial sarcoma with cervical metastasis that was successfully treated.

Mesenchymal Tumors of the Prostate

Prostatic mesenchymal tumors encompass various benign and malignant neoplasms that may derived from the intrinsic prostatic stroma or from associated elements including muscle, connective tissue, blood vessels, and neural structures. The differential diagnosis of these tumors is broad and encompasses prostatic epithelial processes that demonstrate prominent spindle cell morphology, as well as mesenchymal tumors that secondarily involve the prostate. Careful morphologic examination, clinical history, and judicious use of a limited panel of immunohistochemical markers and molecular tests aid in the proper diagnosis of these lesions. This article provides a structured guide for the analysis and diagnosis of both benign and malignant prostatic mesenchymal lesions and highlights key features that distinguish these entities within the differential diagnosis of prostatic spindle cell lesions.

Synovial sarcoma of the kidney

The renal parenchyma is a rare site of origin for primary synovial sarcoma (SS). The present study describes the clinicopathologic, immunohistochemical, and molecular analysis of 7 cases of SS occurring in the kidney. There were 5 female and 2 male patients, with an age range of 15 to 46 years. They presented with solitary renal masses ranging in size from 10.0 cm to 17.0 cm in greatest dimension. Radical nephrectomy was performed in all cases. On gross examination, tumors were large, partially necrotic, and were seen to contain smooth-walled cysts in 4 cases. Histologically, the tumors were characterized by monomorphic spindle cells with indistinct cell borders arranged in intersecting nodular foci with hypocellular myxoid areas, together with a prominent hemangiopericytomatous pattern. The cysts were lined by hobnailed cells with eosinophilic cytoplasm. Immunohistochemically, BCL-2 was positive in all 6 cases in which it was performed, followed by vimentin (4/5 cases), MIC2 (CD99; 2/5 cases), calponin (2/2 cases), and epithelial membrane antigen (1/4 cases). Stains for cytokeratin and CD34 were consistently negative. Reverse transcription-polymerase chain reaction (RT-PCR) using RNA extracted from formalin-fixed paraffin-embedded tissues was carried out in 4 cases and SYT-SSX fusion gene transcript, which is the diagnostic hallmark of SS, was detected. Two patients developed pulmonary metastasis and died 6 and 12 months after diagnosis, respectively. This series of cases is distinct in terms of its morphological spectrum and confirmation by molecular technique.

Nonepithelial Tumors and Tumor-Like Lesions of the Prostate Gland

Many significant benign and malignant nonepithelial tumors and stromal tumor-like lesions arise in the prostate gland. Although such lesions are rare, their recognition by the pathologist is essential because their treatment and prognosis are quite variable. In this review, lesions of the specialized prostatic stroma, that is, lesions that can be seen in the stroma of the prostate but not in that of other organs, except for the phyllodes type of lesions, are discussed. Benign and malignant lesions of the soft tissues that occur in the stroma of other organs and are seen with some frequency in the prostate are also discussed. Few of the rarer soft tissue lesions are mentioned. Lesions and tumors with melanocytic differentiation, hematopoietic derivation, and germ cell tumors are described. It is hoped that this review will serve as a useful reference when encountering some of these lesions, all of which are referenced to their original and subsequent reports. Some non-English language references are also cited to reflect the international recognition of these lesions or to give credit to the author who first described the entity.

The diagnostic value of SYT-SSX detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH) for synovial sarcoma: a review and prospective study of 255 cases

This study aimed to evaluate the diagnostic value of SYT-SSX detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH) for synovial sarcoma (SS) in known and potential cases. SYT-SSX was analyzed in formalin-fixed, paraffin-embedded tissues of 62 known SS, 60 non-SS and 133 potential SS by RT-PCR and FISH. FISH was mainly performed on a tissue microarray with some modifications. SYT-SSX was detected in 94.7% (54/57) of known SS and 70.5% (86/122) of potential SS by RT-PCR and in 96.7% (58/60) of known SS and 78.1% (100/128) of potential SS by FISH. Moreover, SYT-SSX was negative in 100% (58/58) of non-SS by RT-PCR and in 100% (59/59) of non-SS by FISH. Accordingly, SYT-SSX was detected in 106 potential SS by RT-PCR or FISH, including 80 cases manifested by both methods, 20 specimens verified only by FISH and 6 samples confirmed only by RT-PCR. Clinical findings and immunohistochemistry data were analyzed in potential SS with final molecular diagnosis. The positive ratio of cytokeratin (CK) and epithelial membrane antigen (EMA) in finally diagnosed SS was 51.9% (55/106) and 61.3% (65/106), respectively. Except EMA, clinical parameters (age, sex, tumor size, tumor sites) and other immunohistochemistry indexes (CK, S-100, neurone specific enolase (NSE), CD99, myoglobin, smooth muscle actin (SMA), cluster of differentiation (CD) 68 and mesothelial cell) had no significant difference between finally diagnosed SS and non-SS. It is indicated that the efficiency of FISH is comparable to or even higher than that of RT-PCR for SYT-SSX detection. The detection of SYT-SSX by RT-PCR or FISH is very useful for the final diagnosis of potential synovial sarcomas.

Primary Synovial Sarcoma of the Prostate: Report of 2 Cases and Literature Review

Two cases of primary prostatic synovial sarcoma presenting as a prostatic mass are presented in patients aged 44 and 46 years. Histologically, both tumors were mainly composed of uniform spindle cells forming interlacing fascicles. Clusters of immature epithelioid cells were also observed among the spindle cells in case 1. Immunohistochemically, the tumor cells of both cases were strongly positive for vimentin, bcl-2, CD99, and E-cadherin, as well as focally positive for cytokeratin. However, they were negative for prostate-specific antigen, S-100 protein, CD34, CD117, muscle-specific actin, desmin, and calretinin. The presence of an SYT—SSX gene fusion resulting from t(X;18) was demonstrated from paraffin blocks by reverse transcriptase polymerase chain reaction in both cases. To the authors' knowledge, these represent the fifth and sixth reported cases of prostatic synovial sarcoma. Accurate diagnosis depends on morphologic and immunohistochemical examination and proper molecular analysis.

Spindle cell lesions of the adult prostate

Prostatic spindle cell lesions are diagnostically challenging and encompass a broad array of benign and malignant processes. A subset of these lesions arises only within the prostate and generally represents entities that originate from the prostate epithelium or stroma, such as sclerosing adenosis, sarcomatoid carcinoma, stromal tumors of uncertain malignant potential (STUMP), and stromal sarcoma. Another subset of spindle cell tumors that involve the prostate are also found at other sites and include solitary fibrous tumor, leiomyosarcoma, and neural lesions among others. Finally, tumors may secondarily involve the prostate yet present as primary prostatic processes, as is evident with several cases of gastrointestinal stromal tumors (GIST). The utility of ancillary studies, including immunohistochemistry, is often limited and the main criteria for diagnosis are the morphologic findings by routine H&E stain. This review addresses the various entities that may present as spindle cell tumors within the adult prostate and discusses the functional aspects of the differential diagnosis of these lesions.

Biphasic synovial sarcoma of the abdominal wall

Synovial sarcoma arising in the abdominal wall is a rare tumor. We report a case of a 38-year-old man who complained of abdominal pain. Physical examination revealed a firm mobile mass, 25 cm in diameter, in the left lower abdominal wall. The tumor was first thought to be a sarcoma arising from the omentum or mesentery. During surgery, a large tumor was found attached to the inner surface of the abdominal wall and compressing the gastrointestinal tract. On microscopic examination the tumor corresponded to a biphasic synovial sarcoma immunoreactive for cytokeratins (AE1/AE3, 7 and 19), epithelial membrane antigen and carcinoembryonic antigen in the epithelial tumor cells, for E-cadherin especially in their glandular structure, vimentin, CD99, and CD56 in the spindle cell component and for bcl-2 protein. The tumor recurred at the same site, and clinical course progressed to death 3 months after the initial diagnosis.

Primary Intrathoracic Synovial Sarcoma

Synovial sarcoma (SS), an aggressive neoplasm accounting for up to 14% of soft tissue sarcomas, was recently recognized as a primary tumor in the lung and pleura. SS is characterized by the chromosomal translocation t(X;18)(SYT-SSX) found in more than 95% of the tumors. We report a cooperative study from the French Sarcoma Group and the Mesopath Group on 40 t(X;18)(SYT-SSX)-positive primary intrathoracic SS. There were 22 males and 18 females, whose age ranged from 16 to 79 years (median, 47 years). Neoplasms were mostly circumscribed and of large size (median, 7.5 cm; range, 2-16 cm). Thirty-nine tumors were monophasic SS, including 24 (60%) monophasic fibrous and 15 (37.5%) poorly differentiated cases, and one lesion was a biphasic SS. A larger proportion of poorly differentiated tumors were observed among intrathoracic SS as compared with soft tissue SS. Immunohistochemically, 90% of the cases reacted with at least one epithelial marker. CD34 was focally expressed in 3 cases. SYT-SSX1 fusion transcripts were detected in 22 cases (56.4%) and SYT-SSX2 fusion transcripts in 17 cases. Median and 5-year disease-specific survival in 33 patients was 50 months and 31.6%. Median and 5-year disease-free survival was 24 months and 20.9%. Patient sex, age, tumor size, histologic subtype, grade, and SYS-SSX fusion type had no significant impact on outcome. In conclusion, intrathoracic SS are rare but aggressive tumors with poor prognosis. In this unusual location, the detection of SYT-SSX fusion transcripts is a valuable diagnostic adjunct.

Intra-abdominal synovial sarcoma: a clinicopathological study

AIMS

To evaluate a series of synovial sarcomas arising in the abdomen, pelvic cavity, or retroperitoneum. Synovial sarcoma is rare within the abdomen. In this location, it can be confused with other biphasic tumours and with other spindle and round cell sarcomas.

METHODS AND RESULTS

Cases were retrieved from archives. There were 11 intra-abdominal tumours among 300 synovial sarcomas in two referral practices (3.7%). Three were pelvic (two midline, one sidewall) and eight were retroperitoneal. They occurred in six males and five females aged from 25 to 75 years (mean 49 years, median 46 years), and ranged in diameter from 65 to 470 mm (mean 210 mm, median 150 mm). Six examples were biphasic, five were monophasic and seven had poorly differentiated areas. Monophasic tumours displayed at least one epithelial marker. One biphasic tumour had a SYT-SSX2 fusion gene. Seven sarcomas were high-grade and four of intermediate grade malignancy. Follow-up data were available in 10 patients. In all but one case, tumour recurred or metastasized within the abdomen. The pelvic sarcomas also metastasized outside the abdomen. Eight of 10 patients (80%) died of disease with survival from 4 to 36 months (mean 17 months, median 18 months). Two patients were alive with disease at 43 and 48 months.

CONCLUSIONS

Synovial sarcomas rarely arise within the abdomen and pelvis. They occur mainly in middle age, attain a large size, are difficult to excise and recur locally. Pelvic tumours metastasize distantly. Retroperitoneal tumours remain confined to the abdomen and, unlike synovial sarcomas elsewhere, do not metastasize remotely, although mortality is high.

A novel FISH assay for SS18-SSX fusion type in synovial sarcoma

Synovial sarcoma is a morphologically, clinically and genetically distinct entity that accounts for 5-10% of all soft tissue sarcomas. The t(X;18)(p11.2;q11.2) is the cytogenetic hallmark of synovial sarcoma and is present in more than 90% of the cases. It produces three types of fusion gene formed in part by SS18 from chromosome 18 and by SSX1, SSX2 or, rarely, SSX4 from the X chromosome. The SS18-SSX fusions do not seem to occur in other tumor types, and it has been shown that in synovial sarcoma a clear correlation exists between the type of fusion gene and histologic subtype and, more importantly, clinical outcome. Previous analyses regarding the type of fusion genes have been based on PCR amplification of the fusion transcript, requiring access to good-quality RNA. In order to obtain an alternative tool to diagnose and follow this malignancy, we developed a fluorescence in situ hybridization (FISH) assay that could distinguish between the two most common fusion genes, that is, SS18-SSX1 and SS18-SSX2. The specificity of the selected bacterial artificial chromosome clones used in the detection of these fusion genes, as well as the sensitivity of the analysis in metaphase and interphase cells, was examined in a series of 28 synovial sarcoma samples with known fusion gene status. In all samples, the type of fusion was correctly identified by FISH. Thus, the assay described here should be useful for clarifying unresolved chromosome markers and for identifying fusion gene status in samples from which RNA of sufficient quality for PCR could not be extracted.

[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.

Should molecular testing be required for diagnosing synovial sarcoma?

BACKGROUND

The t(X;18) translocation is a specific marker of synovial sarcomas (SS). Detection of SYT-SSX transcripts by polymerase chain reaction (PCR) was tested on preselected specimens of well-established histologic types, but to our knowledge, the diagnostic utility of molecular assays on a series of potential SS in comparison with conventional tools has never been reported.

METHODS

Two hundred four consecutive cases of potential SS submitted for a second opinion were studied prospectively. On the basis of clinical context, histologic aspect, and immunohistochemical profile, the tumors were divided into three categories: 1) diagnosis of SS certain, when the only possible diagnosis was SS; 2) diagnosis of SS probable, when SS was the first diagnosis contemplated, but a differential diagnostic issue was raised by other tumors; 3) diagnosis of SS possible, when the diagnosis of SS was not the first diagnosis considered. Detection of SYT-SSX transcripts was performed using real-time PCR from fixed, embedded tissue as a systematic test.

RESULTS

Sufficient RNA samples were recovered for PCR from 177 specimens (87%). One hundred four specimens (51%) were positive for SYT-SSX transcripts. Tumor sites of SS included the extremities (n = 57), lung (n = 13), trunk wall (n = 12), head and neck (n = 6), and other sites (n = 16). There were 61 monophasic, 22 poorly differentiated, 17 biphasic, and 4 predominantly epithelial SS. For 58 tumor specimens (29%), diagnosis of SS was certain before molecular testing; 49 (84.5%) of these 58 contained SYT-SSX transcripts. For 39 tumor specimens (19%), diagnosis of SS was probable; 29 (74.4%) of these 39 contained SYT-SSX transcripts. For 107 tumor specimens (52%), diagnosis of SS was only possible and strongly challenged by another histologic type. The issue consisted mainly of making the distinction between an SS and a poorly differentiated spindle cell sarcoma (n = 49), a poorly differentiated round cell sarcoma (n = 34), a carcinoma (n = 11), a myoepithelioma (n = 8), or an epithelioid fibrosarcoma (n = 5).Twenty-six tumor specimens (24.3%) contained SYT-SSX transcripts-10, 7, 5, 3, and 1 in the spindle cell tumor, round cell tumor, carcinomalike tumor, myoepitheliomalike tumor, and epithelioid-fibrosarcoma-like tumor categories, respectively.

CONCLUSIONS

Molecular testing was not required if the diagnosis of SS was certain or probable on the basis of clinical, histologic, and immunohistochemical evaluation. However, it proved to be very helpful or necessary when the diagnosis of SS was only possible and was challenged by other tumor types, mainly other spindle cell sarcomas, round cell sarcomas, carcinomas, myoepitheliomas, and epithelioid fibrosarcomas.

Synovial sarcoma in older patients: clinicopathological analysis of 32 cases with emphasis on unusual histological features

AIMS

To analyse the clinicopathological features of synovial sarcoma presenting in patients over 60 years of age, an uncommon subset which have not been specifically studied.

METHODS AND RESULTS

Thirty-two cases of primary synovial sarcoma in patients aged > or =60 years were retrieved from the authors' consultation files. These were analysed histologically and immunohistochemically and clinical follow-up was obtained in 26 cases (median duration 41 months). Mean age at diagnosis was 71.6 years (range 60-84) with 19 females and 13 males. Anatomical sites were lower limb (n = 13), upper limb (n = 5), lung/pleura (n = 5), trunk (n = 4), head/neck (n = 3), mediastinum (n = 1) and scrotum (n = 1). Histologically, 23 were monophasic and nine were biphasic; 14 were poorly differentiated, of which five showed focally marked pleomorphism. Unusual features in two cases each included organoid nodules, granular cell change, squamous metaplasia and papillary architecture. Ten patients developed local recurrence and 11 developed metastases, of whom seven died. Large tumour size, poorly differentiated morphology and high mitotic rate correlated with poor outcome.

CONCLUSIONS

Less than 10% of synovial sarcomas occur in patients over 60, in which age group this diagnosis is often not considered. Despite inevitable bias in consultation material, it seems that these cases, when compared with younger age groups, more often show poorly differentiated histology and more often develop at unusual locations.

Complete resection of synovial sarcoma of prostatic fascia

Synovial sarcomas primarily occur chiefly in the para-articular regions of the extremities and extremely rarely in the prostatic region. We report a patient with synovial sarcoma of the prostatic fascia. The patient underwent retropubic radical prostatectomy and at 6 months of follow-up, no evidence of another lesion or local recurrence was found.

Monophasic fibrous and poorly differentiated synovial sarcoma: immunohistochemical reassessment of 60 t(X;18)(SYT-SSX)-positive cases

Diagnosing monophasic fibrous and poorly differentiated synovial sarcoma (SS) on morphology alone is often a source of problems for pathologists. SS bear the t(X;18)(p11.2,q11.2) translocation, which proved to be specific for this tumor type and is currently considered one of the most reliable diagnostic criteria. To evaluate the sensitivity of immunohistochemical techniques in diagnosing monophasic fibrous SS (MFSS) and poorly differentiated SS (PDSS), we examined 60 t(X;18)(SYT-SSX)-positive cases (47 MFSS and 13 PDSS) for cytokeratin AE1/AE3, cytokeratin KL1, epithelial membrane antigen, E-cadherin, CD34, S-100 protein, alpha-smooth muscle actin, desmin, h-caldesmon, CD99, bcl2, and C-kit (CD117) antibodies. Of the four epithelial markers tested, epithelial membrane antigen proved to be the most sensitive, reacting with 100% of MFSS and 92% of PDSS, followed by cytokeratin AE1/AE3 (70% of MFSS, 46% of PDSS), cytokeratin KL1 (49% of MFSS, 38% of PDSS), and E-cadherin (47% of MFSS, 54% of PDSS). A staining for cytokeratin AE1/AE3 and/or E-cadherin was observed in 79% of MFSS and 69% of PDSS, and a staining for cytokeratin KL1 and/or E-cadherin was observed in 74% of MFSS and 62% of PDSS. S-100 protein was positive in 38% of MFSS and 23% of PDSS, and alpha-smooth muscle actin in 21% of MFSS and 8% of PDSS. Tumor cells were rarely positive for CD34 (6% of MFSS, 0% of PDSS) and desmin (2% of MFSS, 0% of PDSS). Most SS were strongly positive for bcl-2 (91% of MFSS, 92% of PDSS) and CD99 (91% of MFSS, 100% of PDSS). A weak and focal cytoplasmic reactivity for CD117 was observed in 11% of MFSS (only one case had a strong immunoreactivity) and 8% of PDSS. Staining with h-caldesmon was consistently negative. In conclusion, in keeping with literature data, our results show that reactivity for epithelial membrane antigen, cytokeratin AE1/AE3, and E-cadherin, in combination with CD34 negativity, are the most useful and sensitive markers for diagnosing monophasic fibrous and poorly differentiated t(X;18)-positive SS. They also support the fact that about one third of MFSS and one fourth of PDSS are positive for S-100 protein, a finding of diagnostic relevance when considering their distinction from other spindle to round cell sarcomas, especially malignant peripheral nerve sheath tumors.

Losses in chromosomes 17, 19, and 22q in neurofibromatosis type 1 and sporadic neurofibromas: a comparative genomic hybridization analysis

Neurofibromatosis type 1 (von Recklinghausen's NF1) is an autosomal dominant disease associated with an increased risk of benign and malignant neoplasia including malignant peripheral nerve sheath tumors (MPNSTs). In this study, we employed comparative genomic hybridization (CGH) to determine changes in the relative chromosome copy number in 24 patients with neurofibromas, including 12 NF1-associated and 12 sporadic cases. Differences in the frequency and distribution of chromosomal imbalances were observed in both NF1-asociated and sporadic neurofibromas. Chromosomal imbalances were more common in NF1-associated tumors than in sporadic neurofibromas. In both groups, the number of losses was higher than the number of gains, suggesting a predominant role of tumor suppressor gene in tumorigenesis. A number of new chromosomal imbalances were noted including chromosomes 17, 19, and chromosome arm 22q, which may be related to oncogenes or tumor suppressor genes in neurofibromas. In NF1-associated neurofibromas, the most frequent losses were found in chromosome 17 (the minimal common regions were 17p11.2-->p13 in nine cases and 17q24-->q25 in six cases) and 19p (19p13.2 in nine cases). In addition, both NF1-associated and sporadic neurofibromas often exhibited losses at chromosome arms 19q and 22q (in NF1 tumors, the minimal common regions were 19q13.2-->qter in seven cases).

Submandibular synovial sarcoma with t(X;18) and synovial sarcoma of the toe with additional cytogenetic abnormalities: presentation of two cases and review of the literature

We report cytogenetic findings from fine-needle aspiration samples of two synovial sarcoma patients. The cases are of interest because (1) one case is of a rare site (submandibular region) of the head and neck, and (2) the other is a patient with synovial sarcoma of the toe showing additional cytogenetic abnormalities along with t(X;18). The literature of this tumor is reviewed.

Primary synovial sarcoma of the kidney: Report of a case confirmed by molecular detection of the SYT-SSX2 fusion transcripts

We describe an unusual case of primary synovial sarcoma of the kidney. A 47-year-old woman had a tumor massively replacing the right kidney. There were no primary extrarenal neoplastic lesions. Microscopically, the tumor was composed of a cellular proliferation of relatively uniform spindle-shaped cells having atypical spindle or oval nuclei arranged in fascicles with tumor necrosis, without epithelial areas. Immunohistochemically, a small number of the tumor cells were positive for epithelial markers such as cytokeratin and epithelial membrane antigen. The SYT-SSX2 fusion transcripts were detected by a reverse transcription-polymerase chain reaction (RT-PCR) using RNA extracted from formalin-fixed, paraffin-embedded tissue. ETV6-NTRK3 fusion gene transcripts that result from t(12; 15)(p13;q25), which is characteristic of cellular congenital mesoblastic nephroma, were not demonstrated. To our knowledge, this is the ninth case of primary renal synovial sarcoma. This case report indicates that synovial sarcoma should be taken into account for the differential diagnosis of renal spindle cell tumors and the molecular assay detecting the SYT-SSX fusion transcripts is useful for the final diagnosis of synovial sarcoma arising in an unusual location.

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.