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

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.

Mixed epithelial and stromal tumor of kidney with malignant transformation: report of two cases and review of literature

We present 2 cases of mixed epithelial and stromal tumor of the kidney with sarcomatous transformation. One patient was a 53-year-old woman who presented with macroscopic hematuria. The resected tumor involved the right renal parenchyma, measuring 13.0 x 8.0 x 4.0 cm, and extended to perirenal adipose tissue. The second patient was a 56-year-old woman who presented with right flank colic pain. The tumor measured 6.0 x 5.5 x 4.0 cm, with an intact capsule at the upper pole. Both tumors showed a well-circumscribed, multilocular, cystic, and focally solid mass. Sections of both tumors revealed benign and malignant components. The benign component consisted of multilocular cysts and fibrous stroma with a focally ovarian stromalike component. The malignant component in both cases was predominantly composed of undifferentiated cellular spindle cell sarcoma with frequent mitoses. One case showed additional heterologous malignant elements, including rhabdomyosarcomatous, chondrosarcomatous, and focal carcinomatous components. We report 2 additional cases of sarcomatous transformation in mixed epithelial and stromal tumor of the kidney.

Renal tumours of childhood: an update

The role of the pathologist has been fundamental in the progress of the treatment of paediatric renal tumours. There are different philosophies in the treatment of these tumours, and there have been many recent advances in the areas of chemotherapy, identification of new entities, prognostic histological criteria following treatment and molecular prognostic and diagnostic features. This review discusses the different approaches of the different treatment protocols from Europe and North America, and reviews staging criteria, prognostic criteria and also the different tumour entities.

Magnetic resonance imaging features of renal synovial sarcoma: a case report

Primary renal synovial sarcoma (SS) was first described in 2000 by Argani, with only a few subsequent cases being reported in the English literature. Herein, we describe a case of a 52-year-old woman who presented with right flank pain. Magnetic resonance imaging revealed a 6-cm mass in the lower pole of the right kidney. T1 and T2 weighted imaging revealed a heterogeneous mass with triple sign. There was post-contrast enhancement. Imaging, histology and immunostaining together made the diagnosis of SS of the kidney.

Estrogen and progesterone-receptor-positive stroma as a non-tumorous proliferation in kidneys: a possible metaplastic response to obstruction

The presence of estrogen and progesterone-receptor-positive stroma is well known in renal mixed epithelial and stromal tumor, cystic nephroma, and angiomyolipoma with epithelial cysts. It has been suggested that the hormone receptor positivity in mixed epithelial and stromal tumor may be etiologically related to exogenous hormone intake-a phenomenon that has become more frequent in recent years. In the past few years, we have observed such stroma in some non-neoplastic kidneys, as well as in tumor-bearing kidneys away from the tumor. Herein we present our experience with 10 such cases. In a prospective manner, whenever we noted stroma resembling that in ovaries or müllerian organs (endometrial or cervical-like) in kidneys removed for any cause, immunohistochemical stains for estrogen and progesterone receptors were performed. There were eight males and two females among the group, with ages ranging from 11 months to 71 years. In six cases, the nephrectomies were performed for a non-functional kidney, and in three for tumors (one each of chromophobe, clear cell, and acquired cystic disease-associated renal cell carcinoma). One case was a partial nephrectomy for vesico-ureteric reflux, with upper pole hydronephrosis. Such stroma was present in nine cases as a non-mass forming proliferation around dilated, frequently inflamed pelvicalyceal system and collecting ducts. In one it was present at the periphery of an acquired cystic disease-associated renal cell carcinoma, as well as around non-tumorous cysts. The only common finding in all cases was a generalized or segmental hydronephrosis, or tumor compression-related focal obstruction. The stroma was positive for estrogen receptors in all 10 cases, and for progesterone receptors in seven. Thus, estrogen- and progesterone receptor-positive stroma can be present in the kidney, not only as a component of certain tumors, but also in association with non-neoplastic conditions. Its association with obstructive changes suggests that it may represent a metaplastic change in the renal interstitial cells surrounding these obstructed epithelial structures.

Primary synovial sarcoma of the kidney with rhabdoid features

Synovial sarcoma is a soft tissue sarcoma with clearly defined histologic, immunophenotypic, and molecular features. It occurs predominantly in the extremities of young adults but has been reported in many other anatomic sites. Histologically, it is classified as biphasic, monophasic, and poorly differentiated. The latter category, which includes tumors with a rhabdoid morphology, has been associated with a more aggressive behavior. Generally, the biphasic variant does not pose any diagnostic problem because of its typical histologic appearance; in contrast, the monophasic and poorly differentiated variants may represent a diagnostic challenge because their microscopic features can be confused with those of other spindle cell tumors with rhabdoid features. The application of molecular techniques, such as reverse transcriptase polymerase chain reaction to detect the fusion transcript associated with the characteristic t(X;18) translocation of synovial sarcoma, has enabled the confirmation of this diagnosis, even in cases of unusual localization, such as the one we present here.

Anaplastic sarcoma of the kidney: a clinicopathologic study of 20 cases of a new entity with polyphenotypic features

We report 20 cases of a distinct, previously unrecognized renal neoplasm, anaplastic sarcoma of the kidney with polyphenotypic features. The tumors were identified by re-reviewing tumors with unusual anaplastic features from the National Wilms Tumor Study Pathology Center, the International Society of Pediatric Oncology and the United Kingdom Children's Cancer Study Group trials. Patients ranged in age from 10 months to 41 years (median age 5 y, mean age 12 y) and females predominated (1.5:1). Twelve tumors presented in the right kidney, and 5 in the left (laterality was unknown in 3 cases). The most common presentation was a renal mass. Grossly, most tumors were large, measured 4 to 21 cm (mean 12.7 cm) and weighed 115 to 1820 g (mean 835 g). Seven out of 12 tumors suitable for assessment had a distinct cystic component. The tumors involved the pelvi-calyceal system in 5 of the cases. Histologically, all tumors showed a spindle cell component which contained either multiple foci or diffuse, widespread anaplastic changes with bizarre pleomorphic cells and very atypical mitotic figures. Chondroid differentiation was seen in 16 cases, usually in the form of islands of hyaline cartilage (13 cases) or chondroid matrix (3 cases). The nodules of cartilage showed both benign and malignant features, often within the same tumor. In 2 cases small foci of osteoid were found whereas osteoclast-like giant cells were seen in 4 cases. Only 3 of the tumors exhibited a primitive blastema-like area. No neoplastic epithelial structures were identified. No nephrogenic rests were found. Limited immunohistochemical studies showed vimentin positivity in 5/5 cases, desmin was positive in 4/6 cases, MYF4 showed focal weak nuclear positivity in 1/4 cases, but MyoD1 was negative in all cases (0/5). PGP9.5 was focally, strongly positive in 4/5 cases and p53 was strongly positive in 3/6 cases. Cytokeratin, using the antibody CAM5.2, was uniformly negative within the tumor cells. Finally, CD56 was focally positive in 1/6 tumors, whereas all other markers were negative including NB84a (4/4), CD34 (5/6), CD99 (5/5), and WT1 (6/6 cases). In 4 tumors reverse transcriptase-polymerase chain reaction was performed to detect the SYT-SSX fusion transcript produced by the t(x;18), and the ETV6-NTRK3 fusion transcript using RNA extracted from archived paraffin blocks-results were negative in all 4 specimens. Tumor stage was known in 15 patients including 7 stage I, 4 stage II, 3 stage III, and 1 stage IV tumors. They were usually diagnosed as anaplastic Wilms tumors and treated accordingly. Of the 13 patients with a minimum of 2 years follow-up, 4 patients developed distant metastases and 1 had local recurrence including 1 patient with stage IV, 2 with stage III, and 2 with stage I at presentation. Three of them died and 2 were lost to follow-up. One patient with stage I tumor developed widespread metastases and died. Another stage I patient developed local recurrence after 3 months of diagnosis, but was lost to follow-up. Five stage I patients were alive and free of tumor at last follow-up. The most common sites of metastases were lung (3 cases), and liver and bones (2 cases each). These tumors showed pathologic features similar to the pleuropulmonary blastoma of childhood and undifferentiated (embryonal) sarcoma of the liver. In the differential diagnosis, anaplastic Wilms tumor, primary renal synovial sarcoma, malignant mesenchymoma, ectomesenchymoma, and mesenchymal chondrosarcomas have been considered but none of these tumors shared the same features as the 20 cases described here which represent a distinct clinicopathologic entity with morphologic features of a polyphenotypic anaplastic sarcoma of the kidney. Further molecular studies are needed to better understand its nature and more accurate classification.

Cystic nephroma and mixed epithelial and stromal tumour of the kidney: opposite ends of the spectrum of the same entity?

OBJECTIVES

The term "renal epithelial and stromal tumour" (REST) was proposed recently to encompass the spectrum of findings observed in cystic nephroma (CN) and mixed epithelial and stromal tumour (MEST) of the kidney. Our aim was to review the broad spectrum of usual and unusual clinical and morphologic findings observed in CN and MEST.

METHODS

Based on Medline database searches, all aspects of CN and MEST were assessed.

RESULTS

CN and MEST have a remarkable similarity in sex predilection, age distribution, and morphologic attributes of both the epithelial and stromal components and immunohistochemical profile, albeit with variation in individual categories, with higher prevalence of stromal-to-epithelial ratio, prominent ovarian-like stroma, smaller cysts, and stromal luteinisation in MEST, and large cysts, thin septa, and low stromal-to-epithelial ratio in CN. The stromal component in both lesions expresses estrogen and progesterone receptors. Rare and unusual morphologic features, such as endometrioid, cervical, and intestinal differentiation, and luteinised ovarian-like stroma, have been described in MEST. The epithelial element occasionally shows estrogen and progesterone receptors. Rare aggressive behaviour has been reported for both neoplasms.

CONCLUSIONS

Considerable overlap is apparent between the two lesions, which suggests that they may represent opposite ends of the spectrum of the same process. Even though an aggressive behaviour has been reported in very few cases, in general both neoplasms are considered benign and surgical excision is curative.

Malignant mixed epithelial and stromal tumor of the kidney with rhabdoid features: report of a case including immunohistochemical, molecular genetic studies and comparison to morphologically similar renal tumors

Mixed epithelial stromal tumor of the kidney (MEST)/adult cystic nephroma (CN) is a lesion characterized by epithelial lined tubular or cystic structures interspersed within a variably prominent, distinctive spindle-cell stroma. Although typically benign, cases with malignant features have been reported. Herein, we report a MEST/CN with malignant stromal features and rhabdoid differentiation arising in the left kidney of an 84-year-old woman. Histologically, the tumor displayed multiple tubules and variably sized cystic structures lined by benign epithelium with an intervening malignant-appearing spindle-cell stroma. The malignant stroma displayed condensation in the regions surrounding the epithelial component consistent with the ovarian-like stroma typically observed in MEST/CN. In addition, the stromal cells displayed extensive rhabdoid differentiation. Immunohistochemical analysis revealed strong expression of cytokeratin 7, CAM 5.2, AE1/AE3, wide-spectrum keratin, and epithelial membrane antigen by the epithelial component. The stromal component displayed strong immunohistochemical expression of WT-1, CD-99, CD-56, INI1, and estrogen receptor; focal actin positivity; and was negative for desmin, myogenin, and progesterone receptor. Analysis by reverse transcriptase polymerase chain reaction failed to identify the SYT-SSX1 or SYT-SSX2 fusion transcripts characteristic of synovial sarcoma. To our knowledge, this represents the first report in the literature of malignant MEST with rhabdoid features and suggests that this entity should be considered in the diagnosis of renal stromal malignancies with prominent rhabdoid features.

Xp11 translocation renal cell carcinoma in adults: expanded clinical, pathologic, and genetic spectrum

The recently recognized Xp11 translocation renal cell carcinomas (RCCs), all of which bear gene fusions involving the TFE3 transcription factor gene, comprise at least one-third of pediatric RCC. Only rare adult cases have been reported, without detailed pathologic analysis. We identified and analyzed 28 Xp11 translocation RCC in patients over the age of 20 years. All cases were confirmed by TFE3 immunohistochemistry, a sensitive and specific marker of neoplasms with TFE3 gene fusions, which can be applied to archival material. Three cases were also confirmed genetically. Patients ranged from ages 22 to 78 years, with a strong female predominance (F:M=22:6). These cancers tended to present at advanced stage; 14 of 28 presented at stage 4, whereas lymph nodes were involved by metastatic carcinoma in 11 of 13 cases in which they were resected. Previously not described and distinctive clinical presentations included dense tumor calcifications such that the tumor mimicked renal lithiasis, and obstruction of the renal pelvis promoting extensive obscuring xanthogranulomatous pyelonephritis. Previously unreported morphologic variants included tumor giant cells, fascicles of spindle cells, and a biphasic appearance that simulated the RCC characterized by a t(6;11)(p21;q12) chromosome translocation. One case harbored a novel variant translocation, t(X;3)(p11;q23). Five of 6 patients with 1 or more years of follow-up developed hematogenous metastases, with 2 dying within 1 year of diagnosis. Xp11 translocation RCC can occur in adults, and may be aggressive cancers that require morphologic distinction from clear cell and papillary RCC. Although they may be uncommon on a percentage basis, given the vast predominance of RCC in adults compared with children, adult Xp11 translocation RCC may well outnumber their pediatric counterparts.

Recently Described and Emphasized Entities of Renal Neoplasms

Context.—Recent advances of molecular biology and cytogenetics of renal cancer have resulted in the new classification of renal neoplasms and a number of subtypes are identified and emphasized. In addition, rare nonepithelial renal neoplasms are identified and characterized. Familiarity with these entities will help make the most accurate diagnosis and guide the treatment and follow-up of patients with renal neoplasm.

Objective.—To review the clinicopathologic entities of renal neoplasms that are recently defined or emphasized. Their clinical, gross, microscopic, and immunohistochemical features, as well as specific cytogenetic or molecular abnormalities, are discussed. Important differential diagnoses of each entity are also briefly discussed.

Data Sources.—Extensive review of published literature and our experience.

Conclusions.—A number of new entities of renal neoplasms or genetically defined renal cell carcinomas have been identified or emphasized because of their unique genetic or molecular changes. Recognition of these entities becomes important as some of them have different biologic behavior and treatment strategies may be different.

Primary synovial sarcoma of the kidney: corroboration with in situ polymerase chain reaction

Synovial sarcoma is a tumor of the soft tissues with a unique chromosomal translocation t(X;18)(p 11.2;q11.2) that can be detected by polymerase chain reaction in tissue homogenates. The case of a 32-year-old woman with a primary synovial sarcoma of the kidney is described, the diagnosis was corroborated by the recently developed method of in situ polymerase chain reaction (IS-PCR). Synovial sarcoma of the kidney may be confused with other spindle cell tumors, for that reason IS-PCR may be useful to confirm the diagnosis in paraffin-embedded material.

Primary desmoplastic small round cell tumor of the kidney: a case report in a 14-year-old girl with molecular confirmation

We report a case of desmoplastic small round cell tumor (DSRCT) arising in the kidney of a 14-year-old female. The subject presented with gross hematuria. Medical imaging uncovered a left renal mass without regional or metastatic extension. The tumor showed morphological, immunohistochemical, and molecular features of DSRCT. Immunostaining revealed polyphenotypic differentiation. Molecular analysis detected the fusion transcript resulting from the t(11;22)(p13;q12) reciprocal translocation, which characterized this neoplasm. Desmoplastic small round cell tumor is a rare, aggressive neoplasm that mainly affects young males and that usually presents with widespread abdominal serosal involvement. This unusual localization should lead one to consider this tumor in the differential diagnosis of small blue round cell tumors of the kidney.

Immunohistochemistry of primary malignant neuroepithelial tumors of the kidney: a potential source of confusion?

Ewing sarcoma/peripheral primitive neuroectodermal tumor (pPNET) is a rare primary tumor of the kidney with morphologic features similar to those of other primitive tumors. Previous studies have shown that these tumors frequently stain positively with immunostains against CD99 and FLI-1 and negatively with stains against WT-1, suggesting that these markers may be used for the distinction between Wilms tumor and pPNET. We present 30 cases of primary malignant neuroepithelial tumor with immunohistochemical profiles and reverse transcriptase polymerase chain reaction (RT-PCR) analysis and show that immunophenotypic overlap exists between Wilms tumor and pPNET. A subset of 30 neuroepithelial tumors from the National Wilms Tumor Study originally categorized as putative pPNETs of the kidney was stained with FLI-1, WT-1, and thyroid transcription factor-1. Bicolor fluorescence in situ hybridization studies were performed on 19 of the cases. Other data on these tumors were available from a previous study (Am J Surg Pathol 2001;25:133). Of 7 primary tumors that had the EWS/FLI-1 fusion transcript by RT-PCR, 6 exhibited strong immunopositivity for FLI-1. Nine that were negative by RT-PCR stained positively with the FLI-1 stain. Five fusion-negative cases stained with both FLI-1 and WT-1. Three fusion-negative cases were negative for FLI-1 but positive for WT-1. Five fusion-negative cases were negative for both FLI-1 and WT-1. Of the 30 cases, 29 were positive for CD99. Seven cases that were negative for the EWS-FLI-1 fusion by RT-PCR were positive by fluorescence in situ hybridization. All cases were negative for thyroid transcription factor-1. Reliance upon immunohistochemistry as the sole means of ancillary diagnosis in renal pPNET can lead to confusing results. We recommend molecular fusion studies for clarification of primitive renal tumors with unexpected immunophenotypic results.

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.

Malignant Solitary Fibrous Tumor of the Kidney: Report of a Case and Comprehensive Review of the Literature

Renal solitary fibrous tumors (SFTs) have been reported infrequently. We report a 76-year-old man with a left renal mass that had previously been shown radiographically to be stable, but was now growing. Grossly, the mass measured 12 cm, was poorly circumscribed, and invaded beyond the renal capsule. Approximately 10% of the neoplasm consisted of haphazardly arranged spindle cells admixed with dense collagenous bands, which is typical of benign SFT. However, the remainder of the mass was composed of pleomorphic, spindled sarcoma cells with frequent mitoses and foci of necrosis. Immunohistochemically, we observed CD34 labeling in the benign SFT component with loss of expression in the sarcomatous component, focal labeling for Bcl-2 protein in both areas, and absence of labeling for cytokeratin, renal cell carcinoma marker, S100 protein, CD117, and muscle markers in both areas. To our knowledge, this is the first reported case of malignant renal SFT, likely representing transformation from a histologically documented benign SFT component.

Angiomyolipoma With Epithelial Cysts (AMLEC)

Renal angiomyolipoma (AML) is typically a solid lesion, composed of varying amounts of adipose, vascular, and muscular tissue, lacking an epithelial component. Although it is known that entrapped renal tubules may be observed in AML, presentation as a cystic mass has not been previously reported. We report the clinicopathologic and immunohistochemical features of four cystic renal AML. The lesions were found in 2 male and 2 female patients, ranging in age from 37 to 76 years, none with a history of hormonal therapy. One of the four patients had known tuberous sclerosis, and this patient and 1 other presented with bilateral cystic renal lesions. Grossly, the lesions measured between 1.3 and 4.5 cm in greatest dimension. Histologically, the lesions were each composed of three components: 1) epithelial cysts lined by cuboidal to hobnail cells; 2) a compact subepithelial "cambium-like" layer of cellular, müllerian-like AML stroma with prominent admixed chronic inflammation; and 3) muscle-predominant AML with associated dysmorphic blood vessels exterior to the cellular subepithelial stroma. Immunohistochemically, the stromal components of all four lesions labeled with HMB-45 and Melan-A, most intensely in the cellular subepithelial stroma, whereas smooth muscle actin and desmin demonstrated the opposite pattern, with greatest intensity in the muscle-predominant AML areas. Immunoreactivity for estrogen and progesterone receptors (ER, PR) and CD10 was present in all cases, with strongest and most diffuse staining in the subepithelial AML cells. The cyst lining cells were positive for pancytokeratin and soy bean agglutinin (the latter characteristic of distal nephron epithelium) but did not label for ER, PR, or melanocytic markers. Although these distinctive lesions may be confused with mixed epithelial-stromal tumor, their lack of female predominance or association with hormone therapy, their distinctive dysplastic blood vessels and disorganized exterior muscular layer, along with their immunohistochemical profile, support their classification as AML with epithelial cysts. Whereas the cysts appear to arise primarily from entrapped collecting ducts, the peculiar subepithelial condensation of AML stromal cells, with morphologic and immunohistochemical features suggesting differentiation toward endometrial stroma, may represent epithelial-induced müllerian differentiation not previously reported in AML.

An immunohistochemical approach to the differential diagnosis of renal tumors

Renal neoplasms comprise several distinct clinicopathologic entities with potential prognostic and the rapeutic differences. Although careful morphologic examination using sections stained with hematoxylin and eosin will allow for the correct diagnosis in the majority of cases, there is sufficient overlap between several entities such that ancillary techniques may be necessary to arrive at the correct diagnosis. In routine diagnostic surgical pathology practice of renal tumors, immunohistochemistry is the foremost ancillary technique. Using an approach based on common histologic patterns (tumors with clear cytoplasm, granular cytoplasm, tubulopapillary architecture, spindle cell morphology, small round-cell morphology, and infiltrating poorly differentiated carcinoma), we will discuss the utility of immunohistochemistry in the differential diagnosis of renal neoplasms. In recent years, needle biopsies from renal masses are being increasingly performed. In these small biopsies, the entire range of cytoarchitectural features that are generally necessary to make a diagnosis may not be fully appreciated. Immunohistochemistry may be helpful in this setting to narrow the differential diagnosis or to arrive at a definitive diagnosis. Finally, the use of immunohistochemistry for the confirmation of metastatic renal cell carcinoma presenting at distant sites will be discussed. Panels of immunohistochemical stains are proposed for different settings, including renal cell carcinoma (RCC) marker, CD10, and vimentin to suggest renal origin of a metastatic tumor, and markers to aid in subclassification of RCC, including parvalbumin and c-kit for chromophobe RCC, and cytokeratin 7 and alpha-methyl-acyl-CoA racemase for papillary RCC.

The role of genetic testing in soft tissue sarcoma

Soft tissue tumours represent a heterogeneous group of mesenchymal lesions and their classification continues to evolve as a result of incorporating advances in cytogenetic and molecular techniques. In the last decade traditional diagnostic approaches were supplemented with a significant number of reliable molecular diagnostic tools, detecting tumour type-specific genetic alterations. In addition, the successful application of some of these techniques to formalin-fixed paraffin-embedded tissue made it possible to subject a broader range of clinical material to molecular analysis. Thus, molecular genetics has already become an integral part of the work-up in some tumours, such as paediatric small blue round cell tumours, which demonstrate characteristic translocations. Several lines of evidence suggest that sarcomas can be divided into two major genetic groups: (i) sarcomas with specific genetic alterations and usually simple karyotypes, such as reciprocal chromosomal translocations (e.g. FUS-DDIT3 in myxoid liposarcoma) and specific oncogenic mutations (e.g. KIT mutation in gastrointestinal stromal tumours); and (i) sarcomas with non-specific genetic alterations and complex unbalanced karyotypes. Some of these genetic abnormalities, including chromosomal numerical changes, translocations, gene amplifications or large deletions can be apparent at the cytogenetic level (karyotyping, fluorescence in situ hybridization), while others, such as small deletions, insertions or point mutations, require molecular genetic techniques (polymerase chain reaction and sequence analysis). This review focuses on the applicability of genetic testing in the diagnosis and prognosis of soft tissue sarcomas, and gives a realistic appraisal of the ancillary role of molecular techniques, including its advantages and limitations.

Renal cystic diseases: a review

This review aims to assist in the categorization of inherited, developmental, and acquired cystic disease of the kidney as well as to provide a pertinent, up-to-date bibliography. The conditions included are autosomal-dominant polycystic kidney disease, autosomal-recessive polycystic kidney disease, unilateral renal cystic disease (localized cystic disease), renal simple cysts, multicystic dysplastic kidney, pluricystic kidney of the multiple malformation syndromes, juvenile nephronophthisis and medullary cystic disease, medullary sponge kidney, primary glomerulocystic kidney disease, and glomerulocystic kidney associated with several systemic disorders mainly of genetic or chromosomal etiology, cystic kidney in tuberous sclerosis, and in von Hippel-Lindau syndrome, cystic nephroma, cystic variant of congenital mesoblastic nephroma, mixed epithelial stromal tumor of the kidney, renal lymphangioma, pyelocalyceal cyst, peripylic cyst and perinephric pseudocyst, acquired renal cystic disease of long-term dialysis, and cystic renal cell carcinoma and sarcoma. Whereas the gross and histologic appearance of some of these conditions may be diagnostic, clinical and sometimes molecular studies may be necessary to define other types.

Primary synovial sarcoma of the kidney

Primary renal synovial sarcomas (SS) are rare tumors of the kidney. Faria first described primary renal synovial sarcoma in 1999. Twenty-one cases of primary renal synovial sarcoma have been reported to date. Primary renal synovial sarcomas can exist in either a monophasic or a biphasic pattern. The monophasic variant of primary renal synovial sarcoma is more common and tends to have a better prognosis than the biphasic variant. We present the case of a 61 year-old woman with a monophasic variant of primary renal synovial sarcoma.

Bone metastasis of Wilms' tumor with monophasic epithelial histology in a young adult

A unique case of Wilms' tumor with monophasic epithelial histology in the bone metastasis at initial presentation in an 18-year-old Taiwanese girl is presented. Histologically, a purely differentiated epithelial component in the L1-3 vertebrae was noted, which is consistent with the epithelial component in primary Wilms' tumor of the kidney by both microscopy and immunohistochemistry. Hence, Wilms' tumor should be included in the differential diagnosis of a metastatic lesion presenting a purely epithelial histology in a young adult or a child.

Primary renal synovial sarcoma confirmed by cytogenetic analysis: a lesion distinct from sarcomatoid renal cell carcinoma

Primary synovial sarcoma rarely originates in the renal parenchyma. When this occurs, origin of this unusual tumor type has been the subject of debate in the literature, with a suggestion that previously reported cases may be more correctly described as renal cell carcinoma with sarcomatoid dedifferentiation. Synovial sarcoma and sarcomatoid renal cell carcinoma may be indistinguishable on pure histologic and immunohistochemical grounds, but these tumors contain distinctly different sets of chromosomal abnormalities. Most previous cases of primary renal synovial sarcoma were confirmed by molecular biology techniques, which detected the SYT-SSX gene fusion transcript typical of this tumor, but no details of the other chromosomal anomalies have been published. We report a case of primary renal synovial sarcoma confirmed by standard cytogenetic analysis, showing the characteristic t(X; 18)(p11.2:q11.2) translocation and other chromosomal aberrations that are typical of synovial sarcoma as opposed to sarcomatoid renal cell carcinoma.

Metanephric Neoplasms: The Hyperdifferentiated, Benign End of the Wilms Tumor Spectrum?

Metanephric neoplasms represent a spectrum of differentiated lesions that seem most likely to be related to Wilms tumor. These neoplasms include a pure stromal lesion, a pure epithelial lesion (MA), and a mixed epithelial-stromal lesion (MAF). The continuity of these lesions with Wilms tumor has been demonstrated best in the epithelial lesions. The relationship of Wilms tumor, MAF with mitoses or combined MA/Wilms tumor lesions, and usual MAF or usual MA may be viewed as analogous to that of neuroblastoma, differentiating neuroblastoma, and ganglioneuroma, in which progressively more mature or differentiated counterparts of malignant embryonal lesions are associated with a greater probability of benign clinical behavior. Such a spectrum already is recognized for cystic ILNR-derived nephroblastic lesions, ranging from cystic Wilms tumor, cystic partially differentiated nephroblastoma, and cystic nephroma. Although this concept implies that the more active lesions (Wilms tumor) mature with time into inactive ones (usual MAFs or MA), the converse (that an active Wilms tumor can arise within an inactive usual MAF or MA) remains possible.

Tubulocystic Carcinoma, Mucinous Tubular and Spindle Cell Carcinoma, and Other Recently Described Rare Renal Tumors

In the past 10 years, several new renal tumors have been identified. Some have been reviewed in this article, and others have been reviewed elsewhere in this issue. Most have been included in the 2004 edition of the WHO classification of tumors of the urinary system and male genital organs. Tubulocystic carcinoma needs to be studied and characterized more fully.

[Mixed epithelial and stromal tumor of the kidney]

We describe a case of mixed epithelial and stromal tumor of the kidney. The tumor was identified in a 63 years old woman and retroperitoneoscopically resected. Immunohistochemistry, electron microscopy and fluorescence in situ hybridization were performed. Grossly, the tumor was well-circumscribed with a diameter of 8 cm and consisted of solid and cystic components. Microscopically, the spindle cell component ranged in appearance from scar-like fibrous tissue to leiomyoma-like fascicles. Epithelial elements were composed of tubules with variable lining. The tubules were focally transformed into large cysts. Estrogen and progesteron receptors were detected in the nuclei of the spindle cells. Electron microscopy confirmed a smooth-muscle differentiation of the spindle cells. Previously, such tumors were published as adult mesoblastic nephroma or cystic hamartoma of the renal pelvis. Its predominance in females with a history of long-term estrogen replacement or the history of long-term sex-steroid use in a male patient, combined with the expression of estrogen und progesteron receptors in the spindle cells suggest that hormonal influence is relevant for the development of these tumors.

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.

Primary renal sarcoma with morphologic and immunohistochemical aspects compatible with synovial sarcoma

Primary synovial sarcoma of the kidney is a rare tumor that is difficult to diagnose. We present one case that was not diagnosed through fine needle aspiration, requiring a morphologic and immunohistochemical analysis of the incision biopsy. Since the tumor was surgically unresectable, chemotherapy was employed previously to definitive radical surgery.

Late solitary bone metastasis of a primary pulmonary synovial sarcoma with SYT-SSX1 translocation type: case report with a long follow-up

Primary synovial sarcoma outside its classical presentation in para-articular soft tissue of young patients is rare but regularly reported. One of the rarest primary locations is the lung. We describe a 73-year-old female patient who presented with a solitary malignant bone tumor 8 years after the resection of a lung neoplasm. The bone tumor was classified as an osteosarcoma and the lung tumor as an atypical carcinoid tumor at their first respective diagnostic work-ups. The resection of the affected humerus with allograft and endoprosthesis implantation followed. Reevaluation of the tumor samples at the time of the local recurrence of the bone tumor 6 years following the initial symptoms of the bone tumor lead to the reclassification of both specimens as synovial sarcomas. Both neoplasms contained the SYT-SSX1 type of the diagnostic translocation t(X;18) as detected by the reverse-transcription polymerase chain reaction analysis. The patient died 14 years after the resection of the primary synovial sarcoma of the lung and 6 years following the occurrence of the bone metastasis. This prolonged clinical course is uncommon for the SYT-SSX1 translocation, which, in other locations, is usually associated with an unfavorable prognosis.

Usefulness of immunohistochemistry in delineating renal spindle cell tumours. A retrospective study of 31 cases

AIMS

To assess the usefulness of immunohistochemistry in delineating tumour diagnoses on a series of morphologically diagnosed renal spindle cell tumours (RSCTs).

METHODS AND RESULTS

Formalin-fixed paraffin-embedded tissues from 31 morphologically diagnosed tumours were reinterpreted in light of newly obtained immunohistochemical information. By morphology, six had originally been classified as sarcomatoid carcinoma, five as spindle cell tumour (NOS), four as sarcoma (NOS), three as leiomyoma, three as leiomyosarcoma, and one each as fibrous polyp, hamartoma, neurilemmoma, mesoblastic nephroma, medullary fibroma, angiomyolipoma, haemangiopericytoma, malignant rhabdoid tumour, malignant Triton tumour, and carcinosarcoma. The application of immunohistochemistry verified the original diagnosis in 18 cases (18/31, 58%), confirming the diagnosis of sarcomatoid renal carcinoma (4/6), leiomyoma (2/3), leiomyosarcoma (3/3), sarcoma (NOS) (2/4), carcinosarcoma (1/1), malignant rhabdoid tumour (1/1), malignant Triton tumour (1/1), fibrous polyp (1/1), mesoblastic nephroma (1/1), hamartoma (1/1), and angiomyolipoma (1/1). Different tumour designations were suggested in 13 cases (13/31, 42%), including carcinosarcoma, sarcoma (NOS), leiomyosarcoma, solitary fibrous tumour, monomorphic/biphasic angiomyolipoma, endometrial stromal tumour, and congenital mesoblastic nephroma.

CONCLUSIONS

Our data indicate that although morphology is most important in formulating the initial differential diagnosis, the addition of immunohistochemistry is vital in arriving at the correct classification of RSCTs.

A novel case of synovial sarcoma of the kidney: impact of SS18/SSX analysis of renal hemangiopericytoma-like tumors

We report a new case of synovial sarcoma of the kidney. The patient underwent nephrectomy because of a large tumor in the right kidney. The histologic diagnosis was hemangiopericytoma. Less than 1 year after primary surgery the patient was reoperated due to massive local recurrence. Histology now revealed a poorly differentiated tumor tissue with hemangiopericytoma-like features. Immunostainings showed immunoreactivity to cytokeratin, epithelial membrane antigen, and vimentin. The tumor was negative to CD34 and factor VIII. The tumor cell proliferation, assessed by Ki-67, was high. RT-PCR analysis and sequence analysis demonstrated the presence of SS18/SSX2 fusion gene. Review of the histologic specimens from the original tumors confirmed hemangiopericytoma-like morphology. The new diagnosis was poorly differentiated synovial sarcoma. At the time of reoperation, lung metastases were detected radiologically, reflecting a very aggressive phenotype. To our knowledge, this is the third case of poorly differentiated synovial sarcoma of the kidney. Common for all these three cases is the hemangiopericytoma-like histology and a very aggressive clinical behavior. These circumstances accentuate the impact of SS18/SSX analysis in diagnosis of renal hemangiopericytoma-like tumors.

Mixed epithelial and stromal tumors of the kidney. A report of 22 cases

Mixed epithelial and stromal tumor of the kidney (MESTK) is a recently described subset of renal neoplasm that tends to occur in middle-aged and older women and is characterized by a distinctive histological appearance. To further characterize this lesion, we report the clinicopathological and immunohistochemical features of 22 additional cases from our institutional files. Grossly, the tumors ranged in size from 1 cm to 14 cm (mean 6.7 cm), were well circumscribed but unencapsulated, and showed a cystic cut surface. The tumors were composed of a spindle cell proliferation that resembled ovarian stroma, as well as an epithelial component lining the cystic structures, which usually consisted of flat to hobnailed cells typical of collecting-duct epithelium. Areas displaying features of Mullerian differentiation were also documented in 6 cases, including epithelium of endometrioid, tubal, clear cell and squamous cell type as well as one case showing an architecture that closely resembled Mullerian adenofibroma and adenosarcoma. Follow-up in 14 patients (average 4.4 years) showed no evidence of recurrence or metastasis. We believe these tumors represent the renal counterpart of similar mixed epithelial and stromal neoplasms occurring in the biliary tract and pancreas, which is also characterized by cystic structures lined by epithelium, admixed with ovarian-type stroma. The differential diagnosis for these tumors includes cystic nephroma and cystic partially differentiated nephroblastoma, which we believe to represent clinically and morphologically distinct entities from MESTK. In particular, the distinction from cystic nephroma in adult male patients is emphasized, and two cases of this entity are included in the study for comparison.

Favorable response to soft tissue sarcoma therapy in an adolescent with embryonal renal sarcoma

Embryonal renal sarcomas were first identified in 1995 among banked tumor samples originally classified as adult Wilms tumor. Few long-term remissions were observed when these rare tumors were treated with chemotherapy usually used for childhood Wilms. Data were collected from the medical record of an adolescent female with embryonal renal sarcoma and treated with sarcoma-directed chemotherapy and radiation. At 66 months following diagnosis, the patient has no evidence of tumor but has experienced severe renal dysfunction and ovarian failure. We believe there is a subset of patients with disseminated embryonal renal sarcoma that respond to intense sarcoma-directed therapy.

Telomere lengths of translocation-associated and nontranslocation-associated sarcomas differ dramatically

Sarcomas can be divided into those with specific translocations displaying monotonous cytomorphology, and those with complex karyotypes and marked cellular pleomorphism. Telomeres contain terminal DNA sequence repeats that maintain chromosomal stability. Telomeres shorten with cell division and may become dysfunctional leading to chromosomal instability. Using a fluorescence in situ hybridization/immunofluorescence method to assess telomere lengths in archival tissues we analyzed these two types of sarcomas using paraffin-embedded primary tumor specimens. Tissues from nine sarcomas with characteristic translocations (two synovial sarcomas, two alveolar rhabdomyosarcomas, two desmoplastic round cell tumors, and one each of infantile fibrosarcoma, myxoid liposarcoma, cellular congenital mesoblastic nephroma) and nine without (four malignant fibrous histiocytomas, two leiomyosarcomas, one pleomorphic rhabdomyosarcoma, one dedifferentiated chondrosarcoma, and one malignant peripheral nerve sheath tumor) were analyzed. In all (nine of nine) cases with specific translocations, which generally have few karyotypic abnormalities, telomere lengths were similar to or reduced compared to surrounding nonneoplastic tissues. In contrast, telomeres in cases lacking specific translocations, which generally contain complex karyotypes, were often found to be dramatically lengthened and heterogeneous. In addition to markedly elongated telomeres, seven of nine (78%) complex cases exhibited large brightly stained regions corresponding to a specific type of promyelocytic leukemia nuclear body found in immortalized cells that maintain telomeres in a telomerase-independent manner [alternative lengthening of telomeres (ALT) pathway]. This phenotype is unlike that of epithelial neoplasms that typically display complex karyotypes with abnormally short telomeres maintained by the enzyme telomerase. The discovery of heterogeneous telomere lengths and evidence of the ALT pathway in the majority of sarcomas with complex karyotypes supports the existence of a telomere maintenance pathway incapable of full karyotypic stabilization in pleomorphic sarcomas. These findings provide additional molecular-genetic evidence supporting the dichotomous grouping of sarcomas into those with characteristic signature translocations without extensive additional karyotypic abnormalities, and those without such signature translocations that typically display very complex karyotypes, and point to telomere dysfunction as a plausible contributor to the chromosomal aberrations found in complex sarcomas.

Synovial Sarcoma of the Kidney With Rhabdoid Features

We report 3 cases of synovial sarcoma with rhabdoid features, initially diagnosed as adult rhabdoid tumors. Two women (case nos. 1 and 2, 35 years and 27 years of age, respectively) and one man (case no. 3, 26 years of age) presented to their physicians with right flank pain. On physical examination, a poorly defined, firm, palpable mass was found in the upper right quadrant of the abdomen in all cases. Sonography and computed tomography revealed solid, cystic masses in the right kidneys that ranged in size from 8.5 to 20.0 cm. Right radical nephrectomies were performed in all patients. One patient died of disease, and the other two patients were alive and disease-free after chemotherapy and radiotherapy. Microscopic examination revealed that the tumors were composed mostly of rhabdoid cells with eccentrically located nuclei, prominent nucleoli, and eosinophilic cytoplasm. We also found areas of fasciculated spindle cells, sharply separated from or irregularly admixed with areas of rhabdoid cells. There was tumor necrosis, but no epithelial areas were seen. Hemangiopericytic vasculature was at least focally observed in all cases. The tumor cells were positive for CD99 and bcl-2 in all cases and for CD56 in two cases and negative for CD34 and smooth muscle actin in all cases. The cells in case no. 1 were focally positive for cytokeratin. To verify the possibility of synovial sarcoma with rhabdoid features, reverse transcriptase polymerase chain reaction using RNA extracted from frozen tissue in case no. 1 and formalin-fixed, paraffin-embedded tissue in case nos. 2 and 3 was performed. SYT-SSX2 transcripts were detected in all 3 cases. These cases indicate that synovial sarcoma of the kidney should be considered in the differential diagnosis of mesenchymal kidney tumors with prominent rhabdoid features. A subset of adult rhabdoid tumors may be a rhabdoid variant of synovial sarcoma, and molecular studies to detect SYT-SSX fusion transcripts are recommended for an accurate diagnosis.

A case of renal synovial sarcoma: complete remission was induced by chemotherapy with doxorubicin and ifosfamide

We experienced a case of primary renal synovial sarcoma in a 32 year-old woman. On admission, she complained of intermittent abdominal pain. On radiologic examination, a 12 x 10 cm-sized soft tissue mass was detected on the left kidney. The tumor had histologic and immunophenotypic features that were consistent with spindle cell type monophasic synovial sarcoma. Four months after complete resection of the tumor, a unilateral hematogenous metastasis developed in the lung. She was treated with combined chemotherapy of doxorubicin and ifosfamide every four weeks, and complete remission was achieved. We herein describe the case with a brief review.

Molecular Detection of JAZF1-JJAZ1 Gene Fusion in Endometrial Stromal Neoplasms with Classic and Variant Histology

Endometrial stromal tumors (ESTs), including low-grade endometrial stromal sarcomas (LGESSs) and endometrial stromal nodules (ESNs) of classic histology, exhibit characteristic morphologic features and contain the nonrandom t(7;17)(p15; q21), which results in the fusion of two novel genes, JAZF1 and JJAZ1. ESTs may pose diagnostic challenges when they involve extrauterine sites, present as metastases, or display variant histologic appearances. The aim of this study was to evaluate the frequency of the JAZF1-JJAZ1 gene fusion among primary uterine, metastatic, and primary extrauterine ESTs of various histologic types and its role as a possible diagnostic adjunct. Using a nonnested reverse transcriptase-polymerase chain reaction approach, we assayed for JAZF1-JJAZ1 gene fusion transcripts in 10 cases with available fresh-frozen tissue. These included five primary uterine (two classic, one mixed smooth muscle, and one epithelioid LGESS; one classic ESN), four metastatic (two fibromyxoid, one classic, and one epithelioid LGESS), and one extrauterine (classic LGESS) tumor. The same primer set and assay conditions were used on five additional paraffin-embedded cases with adequate RNA, including three primary uterine (one fibromyxoid and one mixed smooth muscle LGESS; 1 mixed smooth muscle ESN) and two intraabdominal recurrent (two mixed smooth muscle LGESSs) ESTs. Two cellular leiomyomas and one ESS cell line (ESS-1) without the t(7;17) at the cytogenetic level were run in parallel as controls. JAZF1-JJAZ1 gene fusion transcripts were detected in five (33%) of 15 ESTs, including three of eight primary uterine, one of four metastatic, one of one extrauterine, and none of two recurrent cases. Most ESTs of classic histology showed evidence of JAZF1-JJAZ1 fusion (4 of 5 cases), whereas only one mixed smooth muscle ESN of 10 variant cases was positive. Positivity for JAZF1-JJAZ1 fusion transcripts was found in four of 10 fresh-frozen samples and in one of five paraffin-embedded ESTs. The control specimens were all negative. In conclusion, our data suggest that ESTs are genetically heterogeneous, with the prevalence of the JAZF1-JJAZ1 fusion being highest among ESTs of classic histology. Hence, the diagnostic utility of a JAZF1-JJAZ1 fusion transcript assay in ESTs may be limited to the classic histologic subset.

Intraneural synovial sarcoma: two cases

We report two cases of intraneural synovial sarcoma. The first patient is a 46-year-old female who presented for several months with soft-tissue mass in the right infra-auricular region. The second patient is a 11-year-old girl who fell and then presented with pain in the area innervated by the right C7 spinal root and a nodule identified in the nerve root foramina. Both lesions were of small size and presented with features of synovial sarcoma. A biphasic variant was found in case 1 and a monophasic variant was present in case 2. Immunohistochemical studies were performed to confirm the diagnosis, excluding the main differential diagnoses, namely schwannoma and malignant peripheral nerve sheath tumor. Ultrastructural study was performed in case 2 allowing exclusion of other possible diagnoses. Molecular studies were performed on paraffin-embedded tissue in both cases and revealed the known characteristic t(X;18)(SYT-SSX) translocation.

[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.

Primary renal synovial sarcoma with inferior vena cava and right atrium invasion

Primary renal synovial sarcoma is an uncommon and perhaps under-diagnosed disease. We report a case of renal tumor in a 19-year-old man. Clinically, the tumor mimicked renal cell carcinoma with renal vein, inferior vena cava and right atrium invasion. Histologically, the tumor consisted of monophasic, high-grade, spindle cell components. The diagnosis was validated by fluorescence in situ hybridization and reverse transcription-polymerase chain reaction, which demonstrated SYT-SSX translocation: a characteristic cytogenetic finding for synovial sarcoma. Our case shows that synovial sarcoma should be considered in the differential diagnosis of renal tumors, especially in adolescents and young adults. Proper molecular analysis should be undertaken to attain a definitive diagnosis.

Recent advances in pediatric renal neoplasia

Over the past 6 years, molecular genetic studies have significantly advanced our understanding of pediatric renal neoplasms. The cellular variant of congenital mesoblastic nephroma (but not the classic variant) has been shown to bear the same t(12;15)(p13;q25) and ETV6-NTRK3 gene fusion as infantile fibrosarcoma, a tumor with which it shares morphologic and clinical features. Rhabdoid tumor of the kidney is characterized by deletion of the hSNF5/INI1 gene, which links it to other rhabdoid tumors of infancy that arise in the soft tissue and brain. Primary renal synovial sarcomas and renal primitive neuroectodermal tumors have become accepted entities, and likely comprise a subset of what had previously been termed "adult Wilms tumor." Renal carcinomas associated with Xp11.2 translocations that result in fusions involving the TFE3 transcription factor gene have been delineated, including a distinctive neoplasm that shares the identical gene fusion as alveolar soft part sarcoma. Most recently, a distinctive type of renal neoplasm with a t(6;11)(p21;q12) has been described, and the cloning of the resulting gene fusion links it to the Xp11 translocation carcinomas. Together, these last two translocation-associated tumors represent a significant proportion of pediatric renal cell carcinomas. This review highlights each of these recent advances.

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.