Primary renal synovial sarcoma: molecular and morphologic delineation of an entity previously included among embryonal sarcomas of the kidney

Synovial Sarcoma of the Kidney: Diagnostic Pitfalls in a Case with Myxoid Monophasic Differentiation and No Epithelial Biomarkers Expression

Synovial sarcomas are soft tissue tumours of uncertain origin, most commonly found in the upper or lower extremities. They are characterised by distinctive chromosomal rearrangements involving the gene SS18. Synovial sarcomas can occasionally arise also in visceral sites, but retroperitoneal SSs are very unusual. Among them, a few primary renal synovial sarcomas have been described in the scientific literature. Primary renal synovial sarcomas tend to be monophasic and often show cystic changes. Histologically, they can closely resemble other primary kidney tumours, mainly paediatric tumours such as nephroblastoma and clear cell sarcoma of the kidney. In the current work, a primary synovial sarcoma of the kidney with unusual morphological features (extensively myxoid stroma and immunohistochemical positivity for BCOR) is described. Molecular analysis, through targeted RNA sequencing, was of invaluable help in reaching the correct diagnosis. Despite locally advanced disease at presentation, the patient showed an unexpectedly brilliant response to chemotherapy.

Intra-Abdominal Epithelioid Neoplasm With EWSR1::CREB Fusions Involving the Kidney: A Clinicopathologic and Molecular Characterization With an Emphasis on Differential Diagnosis

Soft tissue neoplasms, harboring fusions between EWSR1 and FUS with genes encoding CREB transcription factors family (ATF1, CREB1, and CREM), are an emerging heterogeneous group of mesenchymal tumors that differ significantly in morphology, immunophenotypes, and behavior. Recently, EWSR1/FUS::CREB fusions have been recognized to define a group of aggressive neoplasms of epithelioid morphology with multiple growth patterns and a striking predilection for mesothelial-lined cavities. These neoplasms presenting as a primary neoplasm of intra-abdominal visceral organs are rare, which could elicit a wide range of differential diagnoses because of their diverse morphologies and immunohistochemical profiles. We report 3 cases of intra-abdominal epithelioid neoplasms with EWSR1::CREB fusions involving the kidney. This study included 2 female patients and 1 male patient, with age at presentation ranging from 17 to 61 years (mean: 32 years). All the patients underwent radical nephrectomy without adjunctive therapies. Grossly, the tumors were large, and all were solitary masses with sizes ranging from 5.6 to 30.0 cm (mean: 14.5 cm). Histologically, the neoplasms showed infiltrating and indistinct borders and were composed predominantly of monomorphic round-to-epithelioid cells with variable amounts of pale-to-clear cytoplasm, arranged in cords, nests, and sheets and embedded in a sclerotic hyalinized stroma with variable lymphoid cuffing either intermixed or at the periphery. Notably, a hemangiopericytomatous growth pattern was commonly seen. Nuclear atypia was mild, and mitotic activity was scarce. Immunohistochemically, all 3 cases were at least focally positive for epithelial membrane antigen and keratin AE1/AE3, with 2 tumors showing focal MUC4 expression and 1 case displaying diffuse CD34 and focal CAIX positivity. Targeted RNA sequencing identified EWSR1::CREM fusion in 2 cases and EWSR1::ATF1 fusion in 1 case. Subsequent fluorescence in situ hybridization analysis confirmed the RNA sequencing results. On follow-up, 1 patient developed multiple spinal bone metastases 5 months after the surgery while the other 2 patients were free of disease 9 and 120 months after diagnosis, respectively. Our findings demonstrate that intra-abdominal epithelioid neoplasms with EWSR1::CREB fusions may rarely occur primarily in the kidney and should be included in the differential diagnosis of primary renal epithelioid mesenchymal neoplasms.

[Renal synovialosarcoma: What about pyelic cytology to make a diagnosis?]

Synovialosarcoma is a malignant mesenchymal tumor of young adults that occurs in the deep soft tissues, particularly around large joints. When it occurs in more unusual sites, it could present a significant diagnostic challenge. In this case, a 19-year-old girl was treated for a pyloric mass. A pyelic urine cytology performed simultaneously with a pyloric biopsy proved to be a significant element of orientation and perfectly concordant with the histopathological aspect of the pyelic mass after nephrectomy. We report here the first case of renal synovialosarcoma documented in pyelic urine.

A rare case report of recurrent primary intra-abdominal synovial sarcoma: An unusual manifestation

Synovial sarcomas are a rare and aggressive subtype of soft tissue sarcomas that typically affects young adults and involves the extremities. Synovial sarcoma of the kidney is a rare and aggressive tumor with a poor prognosis, accounting for only 1% of all renal tumors. The imaging features of this tumor often overlap with those of other renal tumors, and a definitive diagnosis can only be made through immunohistochemical analysis. In this case report, we present the case of a 55-year-old female with left flank pain, who was diagnosed with primary renal synovial sarcoma following a left-sided radical nephrectomy. Despite initial successful surgical intervention, restaging scans showed local recurrence and metastatic disease, which was subsequently managed with 6 cycles of chemotherapy followed by radiation therapy with palliative intent. This case underscores the importance of early detection and aggressive management of rare renal tumors to improve patient outcomes.

Primary Synovial Sarcoma of the Scrotum

The report outlines a case of synovial sarcoma in the scrotal region. A 36-year-old male presented with a scrotal swelling. The lesion was completely resected, whereas the histopathologic examination revealed a spindle cell tumor. The tumor stained positive for pancytokeratin, AE1/AE3, epithelial membrane antigen (EMA), TLE-1, CD99, and BCL-2. The cytogenetic testing showed a chromosomal translocation in the SS18 gene at 18q11.2, consistent with the diagnosis of primary synovial sarcoma. A year later, the patient developed liver, vertebrae, and lung metastasis, which was treated with systemic chemotherapy. Treatment failed to improve the hepatic lesion that was then resected, while the spine and lung lesions were followed by radiotherapy. The patient is now alive and subject to an outstanding follow-up.

SS18-SSX Expression in a Contemporary Cohort of Primary Renal Synovial Sarcoma: A Multi-Institutional Experience of Fourteen Patients

Primary renal synovial sarcoma is a rare aggressive mesenchymal neoplasm of the kidney that accounts for less than 1% of renal sarcomas. Herein, we describe the clinicopathologic and molecular findings of 14 renal synovial sarcoma patients in one of the largest case series to date and to our knowledge, the only renal synovial sarcoma series to use novel SS18-SSX IHC. Clinicopathologic, IHC, molecular, management, and follow-up data were reviewed and analyzed. Macroscopically, the tumors had either homogeneous, tan-white, and solid (n = 10), variegated and solid (n = 3), or variegated and solid-cystic (n = 1) cut surfaces. Spindle cell (n = 10), round cell (n = 3), and round to epithelioid morphologies (n = 1) were observed. SS18-SSX IHC was positive in all 14 tumors (diffuse, n = 10; multifocal, n = 2; focal, n = 2). All the tumors harbored SS18::SSX1/2 gene rearrangement. Metastases to the liver, brain, and lung (n = 1); liver and bone (n = 1); liver and diaphragm (n = 1) were identified. Adjuvant chemotherapy was administered in 11/12 patients. Follow-up was available for 10 patients (time period range: 5 to 24 months). Four patients died of disease, and six patients are alive with no recurrence or metastasis. As SS18-SSX IHC showed an excellent concordance with the FISH results, this may reliably be used in the IHC panel of spindle/round cell sarcomas of the kidney and as a molecular surrogate for renal synovial sarcoma, particularly in a resource-limited setting. Also, the tumors with focal SS18-SSX expression had lower break apart signals in the FISH assay (19% and 23% in two tumors with focal SS18-SSX IHC positivity).

An Extremely Rare and Demanding Diagnosis of Primary Renal Synovial Sarcoma: A Case Report

Primary renal synovial sarcoma (PRSS) is an extremely rare malignancy. The diagnosis of PRSS is unforeseen due to the absence of clinical and radiological typical aspects. Here, we present a case of a 69-year-old male with complaints of hematuria and left lumbar pain. Abdominal-pelvic computed tomography scan with contrast injection showed a solid mass of 8cm diameter in the left kidney and renal vein tumor thrombus. The patient was further subjected to robotic-assisted left radical nephrectomy and renal vein thrombectomy. We concomitantly performed left adrenalectomy and paraaortic lymphadenectomy. Immunohistochemical and genetic analysis revealed PRSS. This entity is characterized by abnormal chromosomal translocation t(X;18)(p11.2; q11.2) and consequently the characteristic SYT-SSX fusion gene. Due to the disease's rarity and severity, diagnosis and management of PRSS rely upon a demanding and multidisciplinary approach.

Primary Synovial Sarcoma of the Kidney: Diagnostic Approach and Therapeutic Modalities for a Rare Nosological Entity

Synovial sarcoma (SS) is a rare mesenchymal entity that represents 5–10% among soft tissue sarcomas (STS). Primary renal synovial sarcoma (PRSS) is an uncommon, rapidly growing tumor, with potential metastatic dissemination. The main prognostic factors of PRSS include tumor size and histologic grade, while translocation t (X; 18) (p11.2; q11.2) (fusion of SYT gene -chromosome 18- with SSX genes (1, 2 or 4)-chromosome X) is the most common pathognomonic sign. Aggressive surgical resection of the tumor along with concomitant regional lymphadenectomy is the treatment of choice for PRSS, while additional en bloc resection of the adjacent affected organs is often performed. To date, the role of preoperative or postoperative chemotherapy remains equivocal. The prognosis of patients with PRSS is poor, as the 5-year survival rate is only 20–30% and further deteriorates when a high mitotic activity is detected. Local recurrence even after complete R0 surgical excision remains the most frequent cause of death. The aim of this review was to meticulously discuss clinical features, histogenesis, and morphological and immunochemical findings of PRSS, while the role of current diagnostic and therapeutic management of this aggressive neoplasm was emphasized.

Adult Wilms Tumor: Genetic Evidence of Origin of a Subset of Cases From Metanephric Adenoma

The genetics of nephroblastoma (Wilms tumor) occurring in adults is largely unknown, as studies have largely been limited to isolated case reports. We, therefore, studied 14 adult Wilms tumors for genetic alterations, using expanded targeted sequencing on 11 cases. The patients ranged from 17 to 46 years of age (mean and median, 31 y), and there were 8 males and 6 females. Five Wilms tumors harbored BRAF V600E mutations. All of these had better-differentiated areas identical to metanephric adenoma, as has previously been described. In 3 such cases, microdissection studies revealed that the BRAF V600E mutation was present in both the metanephric adenoma and Wilms tumor areas; however, additional genetic alterations (including TERT promoter mutations in 2 cases, ASLX1/ATR mutations in 1 other case) were limited to the Wilms tumor component. These findings suggest that the Wilms tumor developed from the metanephric adenoma. Other adult Wilms tumors harbored genetic alterations previously reported in the more common pediatric Wilms tumors, including WT1 mutations (2 cases), ASLX1 mutations (3 additional cases), NSD2 mutation (1 additional case), and 11p loss (3 cases). In summary, a significant subset of adult Wilms tumors (specifically those of epithelial type with differentiated areas) harbor targetable BRAF V600E mutations and appear to arise from metanephric adenomas as a consequence of additional acquired genetic alterations. Other adult Wilms tumors often harbor genetic alterations found in their more common pediatric counterparts, suggesting at least some similarities in their pathogenesis.

Mixed epithelial and stromal tumours of the kidney with malignant transformation: a clinicopathological study of four cases

Mixed epithelial and stromal tumour of the kidney is a complex benign neoplasm in which malignancy rarely arises. In this study, we report four mixed epithelial and stromal tumours in which sarcoma or carcinoma developed. In the first, a multifocal adenocarcinoma arose and areas of transition from benign to malignant epithelium were observed. Oestrogen and progesterone receptors were diffusely present in the nuclei of the spindle cell stroma of the benign component. The second was a sarcoma in which benign epithelial elements were intermixed. Outside the renal parenchyma, clusters of small benign glands surrounded by oestrogen receptor-positive benign stroma were present, supporting the diagnosis of mixed epithelial and stromal tumour. Fluorescence in situ hybridisation for SYT-SSX translocation and immunohistochemical results, specifically TLE1 -ativity, argued against primary renal synovial sarcoma. The patient died 24 months after surgery. The third tumour consisted of small blue round cells, positive for epithelial membrane antigen, BCL2, CD99, and FLI1. Throughout the tumour, the presence of benign appearing branching tubules in fibromuscular stroma, reactive for smooth muscle actin, desmin and progesterone receptor, supported the diagnosis of mixed epithelial and stromal tumour in which a small round blue cell sarcoma with EWSR1 rearrangement arose. In the fourth tumour, adenocarcinoma with papillary architecture arose in a typical mixed epithelial and stromal tumour. In summary, we present four cases of mixed epithelial and stromal tumour with malignant transformation, two showing carcinomatous and the other two with sarcomatous transformation. Identification of typical benign looking elements and the absence of SYT-SSX translocation are helpful in recognition of this entity.

Primary Renal Sarcoma with SS18::POU5F1 Gene Fusion

We report the first case of a primary renal undifferentiated sarcoma harboring an SS18::POU5F1 gene fusion. The patient was a 38 year-old male diagnosed with a 5 cm renal tumor which invaded the adrenal gland and extended into the renal vein. Microscopically, the neoplasm had a predominantly undifferentiated round cell morphology, with areas of rhabdoid and spindle cell growth. Similar to the previously reported cases with this fusion, by immunohistochemistry the neoplasm expressed S100 protein and epithelial markers (diffuse EMA, focal cytokeratin), suggesting the possibility of a myoepithelial phenotype. This report documents another example of a fusion-positive undifferentiated soft tissue sarcoma occurring as a primary renal neoplasm, adding to the already broad list of such entities. It highlights the crucial role of molecular analysis in establishing a specific diagnosis given the overlapping morphology and immunophenotypes such entities may exhibit. This article is protected by copyright. All rights reserved.

Doxorubicin and ifosfamide for recurrent renal synovial sarcoma: The first case report in Indonesia

Introduction and importance

Synovial sarcoma (SS) is the fourth most common soft tissue sarcoma. The primary treatment for renal SS is radical surgical resection of the tumor. However, there are several stages of SS that need systemic treatment. The consensus regarding systemic treatment remains unclear. Therefore, we reported a case of an 18-year-old male with recurrent renal SS treated with doxorubicin and ifosfamide as systemic chemotherapy.

Case presentation

An 18-year-old male was admitted with a chief complaint of right flank pain for three months. He had a history of radical nephrectomy due to a suspicion of Wilms tumor. The histopathological and immunohistochemistry results showed a SS of the kidney. One year after the surgery, the patient came with a sign of a residual tumor. The diagnosis of recurrent renal SS was established after the physical examination, and Second-line chemotherapy was not administered because the patient refused any further treatment. However, the patient showed a partial response after the first chemotherapy session, indicating the benefit of the treatment.

Clinical discussion

The chemotherapy regimen is generally considered safe and can be widely used in clinical practice. Partial response was shown after six courses of treatment. Ifosfamide-based chemotherapy was also used in some reported cases. Most of the cases reported in the current literature were only managed by surgery without using chemotherapy. These cases had various RFS, ranging from 5 to 25 months.

Conclusion

Doxorubicin and ifosfamide are useful as first-line chemotherapy for recurrent renal synovial sarcoma.

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Synovial sarcoma is a rare tumor.

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There has not been any consensus on systemic treatment for synovial sarcoma.

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Partial response are apparent in patients after receiving six courses of Doxorubicin and Ifosfamide.

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The regimen has a potential role as systemic chemotherapy for recurrent renal synovial sarcoma.

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More trials are needed before the regimen can be used in daily practice.

Primary Renal Synovial Sarcoma Case Series: Clinical Profile and Management of a Rare Entity

Synovial sarcomas occur predominantly in the extremities. Primary renal synovial sarcoma is a rare entity. Very few cases have been reported in the literature. Clinical and radiological features are similar to renal cell carcinoma with the diagnosis being established after surgery based on histopathology, immunohistochemistry, and chromosome studies. There are no established guidelines on the role of adjuvant treatment in the management of this disease. We herein present a series of 3 cases managed at 2 institutions. In the current series, all patients had venous thrombus, and surgery was the mainstay of treatment. One patient received neoadjuvant chemotherapy after a preoperative biopsy which was done as she did not respond to chemotherapy for a presumptive diagnosis of Wilm's tumor.

Knowledge of cytogenetic analysis for synovial sarcoma in sarcomatoid variant renal cell carcinoma

Sarcomatoid change in a renal tumor should undergo cytogenetic analysis of t(x;18) to prevent a missed diagnosis of synovial sarcoma. Surgeons should be vigilant regarding pathological correlation.

Primary Renal Synovial Sarcomas: PAX 8 Immunostaining and Unusual Molecular Findings

Synovial sarcoma (SS) is a high-grade sarcoma that rarely involves the kidney. Eleven renal SS cases were collected in our institution. Immunostaining features and molecular changes of renal SS were further elucidated in this study. PAX 8 was focally positive in 1 monophasic SS and diffusely positive in both the spindled and epithelial components in 1 biphasic SS. These 2 PAX8 expressing renal SS were confirmed by the presence of the classic t(X;18) translocation. Our study also revealed the presence of extra copies of the SS18 in one biphasic SS and one poorly differentiated SS. The SS18 (SYT) gene rearrangement is useful for confirming the SS diagnosis. However, a negative test (FISH or RT-PCR) does not rule out the diagnosis. Although not as common, other chromosomal alterations, such as polysomy 18, indeed occur in renal synovial sarcoma.

Primary renal synovial sarcoma presenting with a retroperitoneal bleed

Synovial sarcomas are most commonly localised in extremities, especially in the lower thigh and knee areas. Comprising less than 1% of all malignancies, retroperitoneal synovial sarcoma is very rare with primary synovial sarcoma of the kidney being even more infrequent and difficult to diagnose. We describe a case report of a renal synovial sarcoma in a young adult who was initially managed as a case of Wunderlich's syndrome secondary to what was believed to be a ruptured renal angiomyolipoma. After biopsy confirmation, the patient was eventually managed with neo-adjuvant chemotherapy followed by a right radical nephrectomy and right hepatectomy. Despite its rarity, synovial sarcoma should be considered as differential diagnosis of a bleeding retroperitoneal soft tissue mass detected in young adults.

Primary Renal Synovial Sarcoma and Clinical and Pathological Findings: a Systematic Review

PURPOSE OF REVIEW

To update epidemiological, diagnostic, and therapeutic information on primary synovial sarcoma of the kidney.

RECENT FINDINGS

A total of 96 studies were analyzed; age at presentation was 38.6±14.2 years, predominant location of tumor was right kidney; frequent reported symptoms at diagnosis were hematuria and pain. For definitive diagnosis, cytogenetic technique was used. Detected oncogene was available in 37.8% cases with fusion of SS18-SSX in most patients. Surgery is treatment of choice, with adjuvant chemotherapy; most frequently ifosfamide-based associated with doxorubicin or epirubicin. Overall median survival was 34 months. Mortality was 29% of the cases which reported death and the recurrence rate was 39.8%. Risk of death was increased in patients with metastases at diagnosis Primary RSS occurs more often in young men. RSS often presents with symptoms and in an advanced stage. Surgical treatment is the most commonly used and chemotherapy for advanced or recurrent treatment.

Desmoplastic Small Round Cell Tumor of the Kidney: Report of a Case, Literature Review, and Comprehensive Discussion of the Distinctive Morphologic, Immunohistochemical, and Molecular Features in the Differential Diagnosis of Small Round Cell Tumors Affecting the Kidney

Desmoplastic small round cell tumor (DSRCT) is a rare, highly aggressive neoplasm typically presenting with widespread involvement of the abdominopelvic peritoneum of adolescent males, usually without organ-based primary. Although it is believed to originate from the serous (mainly peritoneal) membranes, intracranial, sinonasal, intraosseous, and other soft tissue sites are also documented. A chromosomal translocation t(11:22)(p13;q12) signature that fuses EWSR1 and WT1 genes results in the production of a chimeric protein with transcriptional regulatory activity that drives oncogenesis. Integration of clinical, morphologic, immunohistochemical, and genetic data is necessary to arrive at the correct diagnosis, especially when the tumor arises in an atypical site. A 15-year-old male presented with hematuria and was found to have a large renal tumor associated with adrenal, liver, lung, and bone metastases. Histopathologic and immunophenotypic features were distinctive for DSRCT. This diagnosis was confirmed by means of fluorescence in situ hybridization and cytogenetic analysis, which documented the pathognomonic t(11;22) translocation, and by reverse transcription polymerase chain reaction on snap-frozen tissue, which revealed the EWSR1/WT1-specific chimeric transcript. Despite high-dose chemotherapy and radiation therapy targeted to a single T11 vertebral metastasis, the disease progressed, and the patient died 4 years after the diagnosis. A search of electronic databases for DSRCT yielded 16 cases of well-documented renal primaries out of around 1570 cases from all sites gathered from the global literature. Desmoplastic small round blue cell tumor and other primary renal tumors considered in the differential diagnosis with DSRCT are discussed.

Primary Renal Synovial Sarcoma - A rare histology

Renal tumours vary from a benign to highly malignant histology. Here we present a 54 yrs male with a heterogeneous large encapsulated cystic lesion in the right kidney upper pole showing areas of solid component and necrosis with no evidence of metastasis or paraneoplastic features.

Post Right Radical Nephrectomy IHC, showed positive reaction for BCL-2, CD99 and vimentin, suggesting Primary Renal Synovial Sarcoma. The patient was treated with ifosfamide based chemotherapy in view of unpredictable prognosis. We present this case for its rarity and good response to treatment and as a suggestion for differential diagnosis of Renal Cell Carcinoma.

Primary Renal Mesenchymal Neoplasms in Nephrectomy Specimens: A 16-Year Survey of Primary and Incidental Cases From a Single Institution

Context. Primary renal mesenchymal neoplasms are rare but diverse. Several neoplasms of mesenchymal derivation can arise as a primary renal mass; however, incidental tumors are identified in nephrectomies performed for end-stage renal disease or other malignant epithelial renal neoplasms. In this article, we document their frequencies with demographic information in nephrectomy specimens. Design. We retrospectively searched our database for nephrectomy specimens from the year 2000 to 2016. Results. A total of 224 cases were identified with an incidence rate of 4.4% (224/5128). One hundred ninety (85%) neoplasms were benign, 27 (12%) were malignant, and 7 (3%) were of intermediate biologic behavior. The majority of cases occurred in adults (93%, 208/224), and 39% of cases represented an incidental finding. The most common neoplasms were angiomyolipoma (58%) and renomedullary interstitial cell tumor (17%). Malignant mesenchymal kidney tumors are rare (0.39% of nephrectomy specimens). The most common adults' malignant tumors in our survey were synovial sarcoma and Ewing's sarcoma. Conclusion. Primary renal mesenchymal tumors are rare and are mostly benign in nature with many incidentally identified lesions. They arise in different age groups with malignant lesions usually presenting at a younger mean age.

Rare anaplastic sarcoma of the kidney: A case report

BACKGROUND

Anaplastic sarcoma of the kidney (ASK) is a rare and newly recognized renal neoplasm. The tumor usually is extensive and cystic, characterized by pleomorphic spindle cells with marked atypia and associated with multinucleated cells. To date, only 27 cases have been reported in the literature. The authors present an additional case and summarize the relevant knowledge in the literature.

CASE SUMMARY

A 27-year-old previously healthy woman presented with a palpable mass over the abdomen and right flank soreness for one year. After the computed tomography study, the patient underwent right radical nephrectomy obtaining a 1680-g tumor with a size of 18.4 cm × 14.5 cm × 11 cm. The tumor is chiefly composed of anaplastic spindle cells with marked nuclear atypia admixed with multinucleated cells. Immunohistochemical evaluation of tumor cells exhibited diffuse positivity for CD56, p53, and vimentin, and focally positive for desmin. The diagnosis of ASK was established. Unfortunately, a local tumor recurrence followed by a distant metastasis developed within months. The patient died 26 months after the initial surgery. Comparing to the previously 27 cases of ASK, the current case had a relatively worse prognosis, which might be potentially associated with older patient age, larger tumor size, and the lack of en-bloc resection of adjacent organs during the initial radical nephrectomy.

CONCLUSION

This case points out the featured pathological findings for diagnosing ASK and suggests more aggressive management for patients with ASK.

BCOR Overexpression in Renal Malignant Solitary Fibrous Tumors: A Close Mimic of Clear Cell Sarcoma of Kidney

BCOR immunoreactivity is a sensitive and highly specific marker for clear cell sarcoma of the kidney (CCSK). However, a subset of adult renal sarcomas which overexpress BCOR are negative for BCOR genetic alterations, including BCOR gene fusions or BCOR-internal tandem duplication, and thus remain unclassified. We report 5 such undifferentiated renal/perirenal sarcomas which raised the differential diagnosis of CCSK due to their morphologic appearance and strong BCOR immunoreactivity, but which on RNA sequencing proved to be malignant solitary fibrous tumors (SFTs). The neoplasms occurred in patients at an age range of 30 to 62 years. Three patients were females and 2 male. Four were primary renal neoplasms while one was perirenal. All 5 neoplasms were cellular, nonpleomorphic, undifferentiated sarcomas with branching capillary vasculature composed of primitive round to ovoid neoplastic cells with scant cytoplasm and nuclei having fine, evenly dispersed chromatin. None of the cases demonstrated the typical hyperchromatic fusiform nuclei, prominent collagen deposition, or hemangiopericytomatous vasculature of SFT. All 5 cases were strongly immunoreactive for BCOR. Three cases were CD34 negative, where the other 2 were only focally CD34 positive. STAT6 was subsequently found to be positive by immunohistochemistry in all 5 cases. In summary, we report a previously unrecognized mimic of CCSK: malignant SFTs with an undifferentiated/small round cell phenotype along with branching capillary vasculature, strong immunoreactivity for BCOR, and minimal or no immunoreactivity for CD34. As CCSK is treated with a specific chemotherapy regimen, this distinction has therapeutic implications.

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.

Novel SS18-NEDD4 gene fusion in a primary renal synovial sarcoma

We report a primary renal synovial sarcoma with a novel gene fusion and unusual morphology. The patient was a 35-year-old female who was found to have a 5 cm hypocellular, myxoid spindle cell renal neoplasm that subtly permeated amongst native renal tubules. The tumor cells showed elongated hyperchromatic nuclei with ill-defined pale cytoplasm, lacking significant mitotic activity or necrosis. Based on its deceptively bland morphology, the differential diagnosis included mainly benign entities, such as metanephric stromal tumor, mixed epithelial stromal tumor (MEST), and myxoid peripheral nerve sheath tumors. A definitive diagnosis of synovial sarcoma was made only subsequently to RNA-sequencing, which revealed a novel SS18-NEDD4 gene fusion. These results were further confirmed by fluorescence in situ hybridization using custom design break-apart probes for both genes. This case illustrates the utility of targeted RNA-sequencing in the classification of challenging tumors with deceptive morphology and identification of novel gene fusion variants. Apart from the canonical SS18-SSX fusion, this is only the second alternative gene fusion variant described in synovial sarcoma to date, in addition to two cases harboring the SS18L1-SSX1 fusion.

Primary renal synovial sarcoma: A case report

BACKGROUND

Synovial sarcoma, a rare mesenchymal tumor type with unclear histological origin and direction of differentiation, accounts for 6%–10% of soft tissue tumors. It is mainly located near the joints and tendons of the limbs, and occurs primarily in children or young adults. Primary renal synovial sarcoma (PRSS) is very rare, accounting for approximately 1% of synovial sarcomas. It is a spindle cell tumor type affecting mesenchymal tissue, and has morphological, genetic, and clinical characteristics, and a certain degree of epithelial differentiation. It is highly malignant and has the fourth highest incidence among soft tissue sarcomas. Here, we report a case of PRSS and share some valuable information about the disease.

CASE SUMMARY

A 54-year-old male patient was admitted to the hospital for a space-occupying lesion in the right kidney for 2 d upon ultrasound examination. The patient had no cold or fever; no frequency, urgency or pain of urination; and no other discomfort. The results of a hemogram, blood biochemistry, and tumor markers were in the normal range. The patient was examined by computed tomography (CT), which indicated the presence of a soft tissue density shadow with a diameter of approximately 6.8 cm in the right renal pelvis area, showing uneven enhancement. Ultrasound indicated a cystic solid mass of approximately 6.8 cm × 6.5 cm in the right kidney, with an unclear boundary and irregular shape. Meanwhile, color Doppler flow imaging showed dotted blood flow signals in the periphery and interior. Contrast-enhanced ultrasound (CEUS) showed "slow in and fast out" hyperenhancement of the right renal mass after contrast agent injection. The postoperative pathological diagnosis was (right kidney) synovial sarcoma. Despite postoperative adjuvant chemotherapy, tumor recurrence was detected two years later.

CONCLUSION

PRSS is a rare malignant tumor. To date, no characteristic imaging findings have been observed. The diagnosis is confirmed primarily through postoperative pathological immunohistochemistry and SS18 (SYT) gene detection. In this case, CEUS was used preoperatively. We found that PRSS has the characteristic of "slow in and fast out" hyperenhancement, and its particular characteristics have diagnostic value. Postoperative adjuvant chemotherapy is not very effective.

Novel MEIS1-NCOA2 Gene Fusions Define a Distinct Primitive Spindle Cell Sarcoma of the Kidney

We describe 2 cases of a distinct sarcoma characterized by a novel MEIS1-NCOA2 gene fusion. This gene fusion was identified in the renal neoplasms of 2 adults (21-y-old male, 72-y-old female). Histologically, the resected renal neoplasms had a distinctively nodular appearance, and while one renal neoplasm was predominantly cystic, the other demonstrated solid architecture, invasion of perirenal fat, and renal sinus vasculature invasion. The neoplasms were characterized predominantly by monomorphic plump spindle cells arranged in vague fascicles with a whorling pattern; however, a more primitive small round cell component was also noted. Both neoplasms were mitotically active and one case showed necrosis. The neoplasms did not have a distinctive immunohistochemical profile, though both labeled for TLE1. The morphologic features are distinct from other sarcomas associated with NCOA2 gene fusions, including mesenchymal chondrosarcoma, congenital/infantile spindle cell rhabdomyosarcoma, and soft tissue angiofibroma. While we have minimal clinical follow-up, the aggressive histologic features of these neoplasms indicate malignant potential, thus warranting classification as a novel subtype of sarcoma.

Comprehensive Genomic Profiling of Adult Renal Sarcomas Provides Insight into Disease Biology and Opportunities for Targeted Therapies

BACKGROUND

Primary adult renal sarcomas (RSs) are rare aggressive neoplasms. Clinical outcomes are extremely poor, and optimal treatment remains challenging.

OBJECTIVE

To identify genomic alterations (GAs) in patients with RSs.

DESIGN, SETTING, AND PARTICIPANTS

Comprehensive genomic profiling (CGP) was conducted on DNA/RNA extracted from formalin-fixed paraffin-embedded tissue using the FoundationOne Heme/Sarcoma assay in 13 adult, locally advanced or metastatic RSs of various histologic types.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

All classes of GAs, including base substitutions, small indels, rearrangements, copy number alterations, tumor mutational burden (TMB), and microsatellite instability (MSI), were analyzed.

RESULTS AND LIMITATIONS

CGP revealed 55 GAs (4.2 per tumor), 29 of which were clinically relevant genomic alterations (CRGAs; 2.2 per tumor). At least one CRGA was detected in nine (69%) cases. High-level amplifications (more than six copies) involving 4q12 amplicon of the KIT and PDGFRA genes were identified in four (31%) cases (two undifferentiated pleomorphic sarcomas [UPSs], one sarcomatoid renal cell carcinoma, and one myxofibrosarcoma). Both UPSs also had KDR gene amplification in addition to KIT and PDGFRA. Additional CRGAs were found in CDKN2A/B (23%), NF1 (23%), and MET (8%). All RSs were MSI stable, the mean TMB was 3.5 mutations/megabase (Mb), and none (0%) featured TMB >10 mutations/Mb. Limitations include the small sample size.

CONCLUSIONS

RSs are characterized by diverse histology and genomic profiles including 31% of cases with 4q12 amplification harboring the KIT/PDGFRA/KDR genes. Of the tumors, 69% carry CRGAs, which could lead to potential benefit from targeted therapies; however, a low TMB also suggests that these cases are unlikely to respond to checkpoint inhibitors.

PATIENT SUMMARY

This study provides insights into molecular biology of renal sarcoma, a rare aggressive subtype of kidney tumors. We demonstrated that renal sarcomas harbor unique, recurrent, clinically relevant molecular abnormalities that provide new opportunities for targeted therapies.

Mixed Epithelial and Stromal Tumor of the Kidney with Extension into Inferior Vena Cava: Case Report and Discussion of Adult Biphasic Cystic Renal Lesions and the Significance of Vascular Involvement

Mixed epithelial and stromal tumor (MEST) is a biphasic adult renal lesion composed of solid and cystic areas containing spindle cell stroma and epithelium that lines the tubules and cystic spaces. While most MEST lesions are benign, rare cases with malignant morphology and biology have been reported. We present a case of mixed epithelial and stromal tumor of the kidney (MEST) with extension into the inferior vena cava in a young adult male. We discuss the differential diagnosis of MEST in the context of other biphasic cystic renal lesions and the significance of vascular involvement in the setting of an otherwise benign tumor morphology.

Primary synovial sarcoma of the kidney: a case report of complete pathological response at a Lebanese tertiary care center

Background

Primary synovial sarcoma of the kidney is a rare type of soft tissue sarcoma. Its presenting features can resemble those of other renal tumors; rendering its early diagnosis, a dilemma. Several cases of renal synovial sarcoma have been reported in the literature with varying treatment options and outcomes. This article describes a rare case of primary renal synovial sarcoma and reviews all cases in the literature.

Case presentation

A 26-year-old male presented with flank pain and hematuria. Initially diagnosed with Wilm’s tumor, revision of pathology and histology, along with the immunohistochemical profile, confirmed, nevertheless, the diagnosis of primary monophasic synovial sarcoma of the kidney with the SYT-SSX2 fusion transcript. Follow-up, post nephrectomy, revealed recurrence within the lungs and at the surgical bed. Surgical resection followed by adjuvant chemotherapy regimen constituting of Doxorubicin and Ifosfamide, achieved complete pathological response.

Conclusion

In this case report, we emphasize the need for accurate diagnosis and prompt treatment. We propose multimodality treatment approach including surgery along with anthracycline-based chemotherapy to induce complete remission.

Biphasic renal synovial sarcoma with extensive venous tumor thrombosis: A rare presentation

Primary renal synovial sarcoma (SS) is a very rare soft-tissue tumor arising from the kidney. These tumors histologically closely resemble other sarcoma variants. Immunohistochemical and cytogenetic techniques remain the cornerstone in achieving the correct diagnosis. Radical surgical excision is the primary treatment for local tumor control and alleviation of symptoms. Adjuvant chemotherapy, at present, has only a limited role. We report a unique case of a 21-year-old young male with the diagnosis of a biphasic renal SS with extensive venous system thrombosis involving the inferior vena cava, bilateral iliac, and femoral vessels which was managed by radical nephrectomy and tumor thrombectomy followed by adjuvant chemotherapy.

Anaplastic sarcomas of the kidney are characterized by DICER1 mutations

Anaplastic sarcoma of the kidney is a rare tumor (≤25 reported cases) characterized by the presence of cysts, and solid areas composed of bundles of undifferentiated spindle cells, showing marked cellular anaplasia (usually accompanied by TP53 overexpression). These tumors often feature prominent areas of cartilage or chondroid material. Germline mutations in DICER1, encoding the microRNA (miRNA) processor DICER1, cause an eponymous syndrome. Recent reports suggest that anaplastic sarcoma of the kidney should be included in DICER1 syndrome as germline DICER1 mutations are associated with the occurrence of such tumors. Therefore, we sought to determine the following: (1) what proportion of anaplastic sarcoma of the kidney have DICER1 mutations; (2) whether the identified mutations affect both alleles of DICER1 (ie, are biallelic); (3) whether somatic missense mutations in the DICER1 RNase IIIb domain impact miRNA generation; and (4) whether TP53 alteration always occurs in these tumors. DICER1 mutations were evaluated by Sanger sequencing and next-generation sequencing in nine tumor/normal pairs. Impact of DICER1 mutations on miRNA generation was evaluated via an in vitro DICER1 cleavage assay. TP53 status was assessed by immunohistochemistry and next-generation sequencing. Eight of the nine cases had at least one RNase IIIb DICER1 mutation that impacted the generation of miRNAs. There were six tumors with truncating DICER1 mutations and in four of them, the mutation found in the tumor was also detected in adjacent normal tissue, and therefore was likely to be either mosaic or germline in origin. Analysis of mutation phase revealed that two of three tumors had biallelic DICER1 mutations. Six of nine anaplastic sarcomas of the kidney had aberrant TP53 immunohistochemisty with damaging TP53 mutations identified in three cases. Taken together, these data suggest that the great majority of anaplastic sarcomas of the kidney have DICER1 mutations and confirm that these tumors are part of the DICER1 syndrome.

Renal Tumors of Childhood: Radiologic-Pathologic Correlation Part 2. The 2nd Decade: From the Radiologic Pathology Archives

Malignant renal tumors account for 7% of childhood cancers, and Wilms tumors are by far the most common-but not in older children and adolescents. Among individuals in the latter half of their 2nd decade of life, renal cell carcinoma (RCC) is more common than Wilms tumor. The histopathologic spectrum of RCCs in children differs from that in adults. The most common subtype of RCC in children and adolescents is Xp11.2 translocation RCC, which is distinguished by hyperattenuation at nonenhanced computed tomography, a defined capsule, and associated retroperitoneal lymphadenopathy. Papillary RCC is the second most common histologic subtype. It enhances less intensely compared with the adjacent renal parenchyma and has a propensity for calcification. Clear cell RCC is seen in patients with von Hippel-Lindau disease and is distinguished by its relatively hypervascular nature. Medullary carcinoma affects adolescents with the sickle cell trait and is characterized by an infiltrative growth pattern and extensive metastasis at presentation. Angiomyolipoma is seen in children with tuberous sclerosis complex and is often multifocal and hypervascular, with macroscopic fat. Metanephric tumors are central, circumscribed, and typically calcified. Lymphoma usually manifests as multifocal masses, but it may involve a solitary mass or infiltrative pattern. Extensive adenopathy and involvement of the gastrointestinal tract or other organs also may be seen. Primitive neuroectodermal tumor is an aggressive neoplasm that is typically quite large at diagnosis. Knowledge of the clinical, biologic, and histopathologic features of renal tumors in older children and adolescents and their effects on the imaging appearance can help the radiologist offer a useful preoperative differential diagnosis.

Primary Renal Sarcomas With BCOR-CCNB3 Gene Fusion: A Report of 2 Cases Showing Histologic Overlap With Clear Cell Sarcoma of Kidney, Suggesting Further Link Between BCOR-related Sarcomas of the Kidney and Soft Tissues

We report 2 primary renal sarcomas demonstrating BCOR-CCNB3 gene fusions that have recently been identified in undifferentiated round cell sarcomas of bone and soft tissue. These neoplasms occurred in male children aged 11 and 12 years, and both were cystic as a result of entrapment and dilatation of native renal tubules. Both cases were composed of variably cellular bland spindle cells with fine chromatin set in myxoid stroma and separated by a branching capillary vasculature. Both neoplasms demonstrated immunoreactivity for BCOR, cyclin D1, TLE1, and SATB2 in the spindle neoplastic cells and negativity in the prominent capillary vasculature. One case was extensively cystic and had hypocellular areas that simulated cystic nephroma; this neoplasm recurred 3 years later as a solid, highly cellular spindle cell sarcoma in the abdominal cavity. The morphology and immunoprofile of these renal neoplasms was compared with a control group of other sarcomas with BCOR genetic abnormalities, including clear cell sarcoma of the kidney (CCSK), infantile undifferentiated round cell sarcomas of soft tissue/primitive myxoid mesenchymal tumor of infancy, and bone/soft tissue sarcomas with BCOR-CCNB3 gene fusion; along with primary renal synovial sarcoma. Our findings show that the renal sarcomas with BCOR-CCNB3 gene fusion overlap with CCSK. These results are in keeping with a "BCOR-alteration family" of renal and extrarenal neoplasms which includes CCSK and undifferentiated round cell sarcomas of soft tissue/primitive myxoid mesenchymal tumor of infancy (which typically harbor BCOR internal tandem duplication), and BCOR-CCNB3 sarcomas, all of which are primarily driven by BCOR overexpression and have overlapping (but not identical) clinicopathologic features.

Renal Synovial Sarcoma in a Young Pregnant Lady: A Case Report and Clinico-Pathological Profile

Synovial sarcoma is a soft tissue neoplasm with clearly defined histologic, immunohistochemical and molecular features. These tumours usually arise in the extremities of young adults. Their occurrence in the kidney is extremely rare. A 25-year-old pregnant lady in her first trimester was incidentally found to have a left renal mass on perinatal ultrasonography. MRI showed a well encapsulated, heterointense mass replacing the left kidney. Following medical termination of her pregnancy, a radical nephrectomy was performed. Histopathology revealed a primary synovial cell sarcoma of the kidney. Postoperatively, she received ifosfamide based adjuvant chemotherapy. This report highlights the challenges involved in the diagnosis of this extremely rare neoplasm. A high index of clinical suspicion, complimented by the use of immunohistochemistry and cytogenetics during histopathological analysis aide in the diagnosis. Aggressive management with a combination of complete surgical extirpation and chemotherapy gives the best results.

Ewing Sarcoma/Primitive Neuroectodermal Tumor of the Kidney: A Rare and Lethal Entity

Ewing sarcoma/primitive neuroectodermal tumor represents a spectrum of undifferentiated tumors with similar biology that together represent the second most common sarcoma in the pediatric-young adult age range. Very rarely, this tumor presents as a primary neoplasm of the kidney. The clinical presentation of this tumor is not specific, and other renal tumors may present with a similar histologic appearance. Establishing the correct diagnosis is critical because renal Ewing sarcoma/primitive neuroectodermal tumor carries a strikingly dismal prognosis and thus dictates a specific treatment strategy. A low threshold for the use of ancillary molecular tests is recommended, particularly in diagnostically problematic cases. Important considerations with regards to morphology, immunohistochemistry, and molecular alterations will be reviewed here and should be taken into account before rendering this rare and lethal diagnosis.

Primary Ewing's Sarcoma of the Duodenum: A Case Report

We report a case of Ewing's sarcoma arising from the duodenum in a 20-year-old woman who presented with a rapidly progressive ulcerative lesion. The surgical specimen obtained via Whipple's operation revealed a small round-cell tumor (SRCT) in the first and second portion of the duodenum. The tumor cells revealed strong immunoreactivity for CD 99 and vimentin and focal paranuclear dot-like immunoreactivity for cytokeratin. Electron microscopy showed primitive tumor cells with few cytoplasmic organelles, but neither neurosecretory granules nor specific cell junctions were present. On Western blot study, 68-kDa EWS/FLIl fusion protein was detected. The occurrence of Ewing's sarcoma in the gastrointestinal hollow viscus has recently been recognized, and this case expands the known anatomic sites that can harbor Ewing's sarcoma by demonstrating primary duodenal involvement.

A case report of one of the largest {3.63kg} renal tumour removed in the Western Hemisphere. A combined Uro vascular approach for complete removal

INTRODUCTION

This paper describes the technique employed for the removal of the largest renal tumour in the Western Hemisphere and the second largest in the World. It is a road map for Surgeons in Training and should be of interest to other Surgeons/Urologists. This tumour weighed 3.63kg; the world's largest weighed 5.44kg.

PRESENTATION OF CASE

A 52year old male presented with a one year history of progressive weight loss, a gradually enlarging abdomen and no other admissible symptom, including no haematuria. The mass started on his left side of the abdomen. CT scans showed a large tumour arising from the left kidney.

DISCUSSION

A combined Urological and vascular approach was chosen in view of the CT scans images of huge renal veins and collateral vessels. The left pleural cavity was elevated by the mass pushing on the left diaphragm and the heart was also displaced cranially as the mass made its own space. Bowels were displaced as the giant mass reached into his pelvis. A thoraco abdominal supra12 rib bed approach was adopted. The rib was not resected nor was the pleural cavity opened. Histological diagnosis was renal leiomyosarcoma.

CONCLUSION

Large renal tumours or masses are best approached by the Urologist with an experienced vascular/general surgeon as assistant as well as a skilled anesthetist/Intensivist. Optimisation, critical care and early mobilization of the patient by a dedicated nursing staff are essential to minimize complications and ensure a successful end result. The success of this operation underscores what is possible in developing countries.

Updates in Benign Lesions of the Genitourinary Tract

The genitourinary tract is a common site for new cancer diagnosis, particularly for men. Therefore, cancer-containing specimens are very common in surgical pathology practice. However, many benign neoplasms and nonneoplastic, reactive, and inflammatory processes in the genitourinary tract may mimic or cause differential diagnostic challenges with malignancies. Emerging clinicopathologic, immunohistochemical, and molecular characteristics have shed light on the pathogenesis and differential diagnosis of these lesions. This review addresses differential diagnostic challenges related to benign genitourinary tract lesions in the kidney, urinary bladder, prostate, and testis, with emphasis on recent advances in knowledge and areas most common in diagnostic practice.

Primary synovial sarcoma of the kidney: A case report

Synovial sarcoma (SS) is a soft-tissue tumor with a unique t(X;18)(p11.2;q11.2) chromosomal translocation that can be identified by polymerase chain reaction in tissue homogenates. Generally, the tumor occurs in the proximity of the joints. The current study presents the case of a 54-year-old female with primary SS (PSS) of the right kidney; this is an extremely rare tumor accounting for <2% of malignant renal carcinomas. The patient presented with an interrupted right flank pain of 20 years duration, with a precipitating factor of a hematuria of 8 days. Abdominal computerized tomography (CT) scan revealed a heterogeneous, unclear-marginated soft tissue arising in the upper pole of the right kidney with solid, necrotic components and heterogeneous enhancement. Renal cell carcinoma was diagnosed pre-operatively. A right nephrectomy was performed, and the patient is currently free of metastasis 12 months after the surgery. The current treatment for renal SS includes surgical resection and ifosfamide-based chemotherapy. To the best of our knowledge, <50 cases have been reported in the English literature. Urologists should be aware of the possibility of malignancy in cystic renal masses and consider a diagnosis of SS. Along with the case report, the current study presents a literature review on the diagnosis and treatment of PSS.

Primary renal sclerosing epithelioid fibrosarcoma: report of 2 cases with EWSR1-CREB3L1 gene fusion

We report the first 2 genetically confirmed cases of primary renal sclerosing epithelioid fibrosarcoma (SEF), occurring in a 17-year-old boy and a 61-year-old woman. In both cases, the tumors demonstrated the typical epithelioid clear cell morphology associated with extensive hyalinizing fibrosis, raising the differential diagnosis of solitary fibrous tumor, metanephric stromal tumor, and the sclerosing variant of clear cell sarcoma of the kidney. Both neoplasms demonstrated diffuse immunoreactivity for MUC4, a highly specific marker for SEF, and both demonstrated evidence of rearrangement of both the EWSR1 and CREB3L1 genes, which have recently been shown to be fused in this entity. Both neoplasms presented with metastatic disease. Primary renal SEF represents yet another translocation-associated sarcoma now shown to arise primarily in the kidney.

Clear cell sarcoma of the kidney distinguished from synovial sarcoma using genetic analysis: a case report

Background

The most common pediatric renal neoplasm is Wilms tumor, but clear cell sarcoma of the kidney or synovial sarcoma of the kidney are also sometimes encountered. Accurate pathological diagnosis is important, because adjuvant therapies including chemotherapy and radiotherapy differ according to the pathological type.

Case presentation

A 9-year-old boy presented with a headache, and ultrasonography, computed tomography, and magnetic resonance imaging revealed a heterogeneous enhancement of soft tissue originating from the upper pole of the left kidney, measuring approximately 11.0 × 10.0 × 8.0 cm. A left radical nephrectomy was performed using an intraperitoneal approach through an anterior subcostal incision. Pathological examination suggested clear cell sarcoma of the kidney or synovial sarcoma of the kidney based on morphological and immunohistological features. Using genetic analysis, a final diagnosis of spindle cell pattern clear cell sarcoma of the kidney was made based on the absence of the SYT-SSX fusion gene. After adjuvant chemo-radiotherapy was administered, no recurrence or metastasis has been identified as of 60 months postoperatively.

Conclusion

In this case, it was difficult to discriminate clear cell sarcoma of the kidney from synovial sarcoma of the kidney based on histopathological examination alone, and genetic analysis was required. Accurate pathological diagnosis of pediatric renal tumor is important for determining optimal treatment and preventing recurrence and metastasis.

Primary renal synovial sarcoma: computed tomography imaging findings

BACKGROUND

A synovial sarcoma arising from the kidney is extremely rare. To date, few data are available on their radiological features.

PURPOSE

To identify the computer tomography (CT) imaging findings of primary renal synovial sarcomas (PRSSs).

MATERIAL AND METHODS

Five cases of PRSS confirmed by histopathological and cytogenetic studies were retrospectively analyzed. All patients had undergone unenhanced and multiphase enhanced CT examinations (one patient underwent CT twice). The CT characteristics, including shape, size, margin, attenuation, and enhancement pattern after intravenous contrast medium injection, were analyzed.

RESULTS

The study involved two female and three male patients (mean age, 27.4 years; range, 15-43 years). Unenhanced CT showed completely or partly well-defined masses, with heterogeneous (n = 5) or homogeneous (n = 1) patchy low density. On multiphase contrast-enhanced CT, in five of the six CT examinations, the tumors appeared as solid-cystic masses with cyst walls or pseudo-capsules, and demonstrated moderately heterogeneous (n = 5) and/or septate enhancement (n = 2), with a "rapid wash-in and slow wash-out" pattern of enhancement in the solid component. Only one tumor showed a simple cyst appearance and developed an irregular, intratumoral, septate soft density 8 months later. A renal vein and inferior vena cava thrombus was noticed in one patient, while lymphadenopathy was not observed in any patient.

CONCLUSION

PRSS should be included in the differential diagnosis when an adolescent or young adult presents with a renal neoplasm appearing as a solid-cystic mass with well-defined borders, a cystic wall or pseudo-capsule, heterogeneous or septate enhancement, a "rapid wash-in and slow wash-out" pattern of enhancement in the solid component, and no sign of lymphadenopathy.

Soft tissue sarcomas of the kidney

Soft tissue sarcomas are rare mesenchymal tumors. Amongst others, primitive neuroectodermal tumors (PNET) of the kidney and synovial sarcoma of the kidney belong to the group of soft tissue sarcomas. Synovial sarcomas can occur almost anywhere in the body, most frequently, however, in the lower (62%) or upper extremities (21%). Metastases occur in 50-70% of cases, and thus the prognosis is poor. PNETs are rare, highly aggressive neoplastic lesions which mainly occur in the torso or axial skeleton in young adults. The prognosis is poor with a 5-year disease-free survival rate of 45-55%. The primary therapeutic approach is surgical resection. Most randomized studies assessing adjuvant chemotherapy for all types of localized soft tissue sarcomas did not show statistically significantly better overall survival times after chemotherapy, although they did show longer progression-free survival. We report on two cases of primary renal synovial sarcoma and one case of PNET of the kidney.

Primary synovial cell sarcoma of the kidney: case report and review of the literature

Synovial cell sarcoma (SCS) of the kidney is a rare tumor entity with a poor prognosis. Morphologic and immunohistochemical characteristics may overlap with other more common neoplasms of the kidney. Therefore, the diagnosis of primary renal SCS not only requires the exclusion of similar tumor types, but also a confirmation of SYT-SSX gene fusion using molecular techniques. The treatment comprises radical surgery, and, depending on age and health status, adjuvant chemotherapy in selected patients. Here, we present an elderly SCS patient in whom straightforward radical surgical treatment resulted in a sustained complete remission; it allowed us to perform a literature survey focusing on current diagnostic tools for SCS.