Ultrastructural differences between synovial sarcoma and solitary fibrous tumor: comparative study in adult patients from the National Cancer Institute of Mexico.

Synovial sarcoma (SS) and solitary fibrous tumor (SFT) are entities with considerable morphological and immunohistochemical similarities that sometimes show a non-confirmatory profile (TLE1 negative, CD34 and focal or negative STAT6 and lack of specific fusion IHC markers), in which the utility ultrastructure is unknown. A cross-sectional, retrospective, analytical, nonexperimental study was carried out by the Department of Pathology of the National Cancer Institute of Mexico (INCan) e from January 1, 2009 to December 31, 2018. With 17 SFT cases with diffuse or focal CD34 and STAT6 positivity and 18 cases of SS with positive FISH molecular test t(X:18) breakapart were studied by electron microscopy of fresh glutaraldehyde fixed or paraffin-embedded tissue. The ultrastructural findings with a significant difference present in the SS were tandem tight junctions, desmosomes and abundance of dilated rough endoplasmic reticulum (RER) cisternae (p < 0.001, 0.003, and 0.001, respectively); while in the (SFT) the presence of abundant glycogen, basal lamina, long and slender cytoplasmic processes, pinocytic vesicles, hemidesmosomes, and/or dense plaques, collagen skein, and microvilli-like buds (p = 0.028, 0.005, and <0.001 for the last five). We then infer that the five distinctive markers of the SFT are the collagen skeins intermingled with cellular processes in a shape of "squid can," and the pinocytic vesicles as they were not observed in any case of SS. Conversely, tandem junctions were not found in any SFT case. Although the presence of multivesicular buds in the SFT was not significant, it had not been previously described.

Canine intrathoracic sarcoma with ultrastructural characteristics of human synovial sarcoma - case report.

BACKGROUND: Canine joint sarcomas, designated synovial sarcomas, are uncommon malignant mesenchymal neoplasms that occur in the large joints of the extremities of middle-aged, large-breed dogs. We report the diagnosis of an intrathoracic sarcoma with ultrastructural characteristics reminiscent of human synovial sarcoma in a dog. CASE PRESENTATION: A 7-year-old female spayed Tibetan terrier crossbred dog was presented for acute severe labored breathing and diagnosed with an intrathoracic neoplastic mass. The neoplasm resulted in the accumulation of substantial amounts of viscous pleural fluid that led to dyspnea. The neoplastic mass consisted of interweaving bundles of large pleomorphic mesenchymal cells, supported by an alcian blue positive myxomatous matrix. The neoplastic cells were immunohistochemically negative for cytokeratin and CD18. Transmission electron microscopy indicated that the neoplastic cells had desmosome junctions, short microvilli-like structures and ample amounts of rough endoplasmic reticulum resembling type B-like synoviocytes and synovial sarcoma as reported in people. Despite complete surgical excision of the neoplastic mass, clinical signs recurred after a month and led to the euthanasia of the dog. CONCLUSION: Currently, there are no immunohistochemical markers specific for synovial sarcoma. Canine neoplasms with transmission electron microscopy characteristics resembling type B-like synoviocytes should be considered similar to the human sarcomas that carry the specific translocations between chromosomes X and 18.

CT imaging of primary pleuropulmonary synovial sarcoma.

AIM: To evaluate the computed tomography (CT) imaging findings of primary pleuropulmonary synovial sarcoma. MATERIALS AND METHODS: Five cases of synovial sarcoma confirmed by histopathology and cytogenetic study were retrospectively analysed. All patients had undergone chest radiography and unenhanced and contrast-enhanced CT examinations, and three had also undergone multiphase CT enhancement examinations. Image characteristics, including shape, size, margin, and attenuation of each lesion before and after contrast enhancement, were analysed. RESULTS: The chest radiographs of the five patients showed well-defined or partly well-defined masses, which were homogeneous and without associated calcification or lymphadenopathy. Pneumothorax was present in one patient. The unenhanced CT images showed well-defined, heterogeneous masses with patchy low density in all five patients. The contrast-enhanced CT images showed heterogeneous enhancement in all cases, three of which demonstrated cystic and necrotic areas. The tumour showed no prolonged or delayed enhancement in three cases using multiphase CT. There were small pleural effusions in four cases. No calcification was observed in any of the cases. There was no evidence of hilar or mediastinal lymphadenopathy. CONCLUSIONS: In these five patients, primary pleuropulmonary synovial sarcoma presented as a well-defined mass with patchy low density and heterogeneous enhancement, with no evidence of regional lymphadenopathy. It should be included in the differential diagnosis of regional tumours.

Inhibin-α and synaptophysin immunoreactivity in synovial sarcoma with granular cell features.

We recognized immunoreactivity for the α subset of inhibin and synaptophysin in synovial sarcomas with granular cell features. Histologic findings of 90 cases of synovial sarcoma were reviewed. Two (2.2%) of the 90 cases had granular cell features, showing sheet or nested proliferation of characteristic epithelioid cells with abundant eosinophilic and granular cytoplasm, in addition to the typical spindle cell component. The 2 cases were both female (aged 86 and 76 years). The tumors were located in the foot and the retroperitoneum and measured 3.5 and 14 cm in maximum diameter. Reverse transcriptase polymerase chain reaction analysis revealed SS18-SSX1 transcripts in both cases. SS18 gene rearrangement was detected in granular cells as well as spindle cells by chromogenic in situ hybridization. Immunohistochemistry found the granular cells to be positive for inhibin-α in both cases and for synaptophysin in 1 case, whereas spindle cells were not. Thirty-six cases (20 monophasic fibrous, 11 biphasic, and 5 poorly differentiated synovial sarcomas) were additionally examined for comparison; they showed no immunoreactivity for inhibin-α or synaptophysin. This is the first report of immunoreactivity for inhibin-α and synaptophysin in synovial sarcoma. These immunohistochemical findings might be characteristic of synovial sarcomas with granular cell features.

SYT-SSX fusion is absent in sarcomatoid mesothelioma allowing its distinction from synovial sarcoma of the pleura.

The diagnosis of sarcomatoid mesothelioma is still a worldwide challenge and it is often difficult, both clinically and by morphological analysis, to differentiate sarcomatoid mesothelioma from synovial sarcoma, the most frequent intrathoracic sarcoma. To confirm the absence of the synovial sarcoma translocation t(X; 18) (SYT-SSX) in sarcomatoid mesothelioma, and to test its usefulness differentiating sarcomatoid mesothelioma from synovial sarcoma, 28 tumours were examined using the reverse transcriptase-polymerase chain reaction. RNA was extracted from paraffin blocks using standard methods, reverse-transcribed and PCR performed. Molecular analysis completed in two independent laboratories showed that sarcomatoid mesothelioma samples were negative for the t(X-18). This result confirms the usefulness of this analysis in differentiating sarcomatoid mesothelioma from synovial sarcoma.

[Monophasic synovial sarcoma: comparison of immunohistochemical and ultrastructural phenotypes and problems of differential diagnosis].

Diagnostics of monophasic synovial sarcoma is highly complicated mostly due to a wide range of cellular and histologic variation. This calls for use of additional examination techniques such as immunohistochemical and electron microscopic.

Well-differentiated biphasic synovial sarcoma in the atlanto-occipital joint of a Holstein cow.

A 7-year-old Holstein cow developed a large cystic mass in the region between the atlantoaxis and larynx. The mass extended to the synovium in the atlanto-occipital joint. Many villous projections were present on the inner surface of the tumor tissue, and irregular clefts were formed in the inside. Two cell types, epithelioid-like synovioblasts and spindle cells, were present. Immunohistochemical analysis showed that the cells stained positively for cytokeratin (AE1/AE3) and vimentin. Both cells had similar fine structures ultra-structurally. Vacuoles present in the cytoplasm were full of an acid mucous substance. The tumor was diagnosed as a well-differentiated biphasic synovial sarcoma. This is the first report of a rare case of synovial sarcoma, from the viewpoint of its origin.

Aberrant expression of tight junction-related proteins ZO-1, claudin-1 and occludin in synovial sarcoma: an immunohistochemical study with ultrastructural correlation.

Synovial sarcoma demonstrates epithelial differentiation, either by light microscopy (biphasic synovial sarcoma) or by immunohistochemical/ultrastructural methods only (monophasic) and poorly differentiated synovial sarcoma. Although the glands of synovial sarcoma are known to have tight junction-like structures, far less is known about junction formation in the spindled component of synovial sarcomas. Additionally, it is unknown whether the tight junctions of synovial sarcoma are normally constituted. The tight junction is a multiprotein complex consisting of numerous proteins that include ZO-1, claudin-1 and occludin. A total of 35 cases of synovial sarcoma (13 biphasic, 14 monophasic and eight poorly differentiated) were immunostained for ZO-1, claudin-1 and occludin using commercially available antibodies, heat-induced epitope retrieval and standard avidin-biotin technique. When available, corresponding electron micrographs were reviewed. For five cases, the presence of either an SYT-SSX1 (three cases) or SYT-SSX2 (two cases) gene fusion was known. Positive cases showed particulate membrane staining. The glands of biphasic synovial sarcomas expressed ZO-1 (13/13), claudin-1 (12/13) and occludin (11/13) in a manner identical to normal glandular epithelia, at the apical portion of the lateral membrane. The spindle cells of biphasic synovial sarcomas showed abnormal circumferential membranous expression of ZO-1 (12/13), claudin-1 (6/13) and occludin (3/13). Monophasic synovial sarcomas expressed ZO-1 in a circumferential pattern (13/14) but less often claudin-1 (4/14) or occludin (3/14). Poorly differentiated synovial sarcomas expressed ZO-1 (8/8) and claudin-1 (6/8) but only rarely occludin (2/8). By electron microscopy, recognizable tight junctions were seen only in glands. No correlation was seen between histologic subtype or fusion type and expression of tight junction proteins. We conclude that the glands of biphasic synovial sarcomas show well-organized, true epithelial tight junctions. In contrast, the spindled cells of all synovial sarcomas show significant abnormalities in the expression and localization of tight junction proteins, suggesting partial and/or aberrant epithelial differentiation.

Monophasic synovial sarcoma: a cytologic spectrum.

Synovial sarcoma (SS) is a high-grade sarcoma that can be diagnosed in cytology with certainty only when it presents with a biphasic pattern. Monophasic SS (MSS), however, is a diagnostic consideration when a uniform spindle cell population is present. The purpose of this study was to evaluate a series of cytologic cases of MSS and its cytologic presentation. Twenty-one FNAs of histologically confirmed MSS were reviewed. Specimens consisted of tissue fragments and single cells containing scant granular cytoplasm, medium-sized nuclei, and coarse chromatin. A monotonous spindle pattern with comma-shaped nuclei was present in 5 cases. Sixteen cases contained oval and spindled nuclei. Eight of these specimens contained round nuclei, and 5 of these cases showed prominent nucleoli and cohesive clusters, reminiscent of biphasic SS. We conclude that a spectrum of cytologic findings can be seen in MSS, including a secondary population of cells with morphology usually typical of biphasic SS.

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.

Fine-needle aspiration of synovial sarcoma: criteria for diagnosis: retrospective reexamination of 37 cases, including ancillary diagnostics. A Scandinavian Sarcoma Group study.

The cytologic criteria of synovial sarcoma in fine-needle aspirates were defined by a retrospective examination of 37 primary tumors. Irrespective of subtype, a typical pattern at low power was found, provided the yield was rich. The typical pattern was a mixture of dispersed cells with the presence of striped nuclei and cell-tight tumor tissue fragments with irregular borders. Often a branching network of vessels was present in the fragments, imitating a true vascular tumor. Except in poorly differentiated synovial sarcomas, the tumor cells were, small to medium in size, with rounded, ovoid, or fusiform bland nuclei with inconspicuous nucleoli. In the biphasic variant, small glandular- or acinar-like structures were present, although not in all cases. In the poorly differentiated type, however, the cellular pleomorphism was marked with the presence of cells with irregular nuclei and rhabdomyoblast-like cells, corresponding to the pleomorphic variant. The Ewing's sarcoma-like and the atypical spindle cell variants of poorly differentiated synovial sarcoma were not diagnosed in the material. An unequivocal diagnosis of sarcoma is possible when the yield is rich. However, ancillary diagnostics are necessary for a correct diagnosis, to avoid important pitfalls, such as other sarcomas with bland tumor cells and vessel-rich tumor fragments, in particular, solitary fibrous tumor and true hemangiopericytoma. Electron microscopic and/or molecular genetic analyses were better diagnostic adjuncts than immunocytochemistry.

Synovial sarcoma arising from the pleura: a case report with ultrastructural and immunohistological studies.

Synovial sarcoma commonly occurs in the para-articular regions of the extremities, and rarely in the pleura. We report a 46-year-old woman with primary synovial sarcoma of the pleura. She was admitted with a complaint of left-sided chest pain and exertional dyspnea. She had previously undergone two operations for pleural neoplasm, at the ages of 33 and 36 years. A computed tomography scan revealed an expanded mass in the left thoracic cavity, involving the surrounding tissue. Macroscopic findings demonstrated a 25 x 25 x 15-cm grayish-white mass with hemorrhage beneath the pleura. Both epithelial and spindle cells were observed microscopically. Ultrastructural microscopy of the epithelioid cells demonstrated short, blunt microvilli on the luminal surface, and desmosomes between the neoplastic cells. Immunohistochemically, the tumor cells of the epithelial component were positive for embryonal membrane antigen (EMA), carcinoembryonic antigen (CEA), human mesothelial cells (HBME)-1, and cytokeratin, and the spindle cells were positive for vimentin. These findings led us to a diagnosis of primary synovial sarcoma of the pleura. She had no evidence of recurrence or metastasis after the third operation.

Malignant peripheral nerve sheath tumor with a t(X;18).

We describe an ankle tumor arising in a 16-year-old girl. The tumor demonstrated histology typical of a malignant peripheral nerve sheath tumor (MPNST), but exhibited a variant form of the (X;18) translocation associated with synovial sarcoma. Immunohistochemical stains were positive for vimentin, CD57, collagen type IV, and Bcl-2. Routine and molecular cytogenetic studies showed an unbalanced 3-way chromosomal translocation that involved chromosomes X, 18, and 1. Electron microscopic findings were noncontributory. This unusual tumor raises the following questions and possibilities: (1) As the t(X;18) suggests, could this tumor be a monophasic synovial sarcoma with the histologic features of an MPNST? (2) Or, as the histology suggests, is this tumor an MPNST that has a t(X;18)? (3) Finally, could MPNST histology, a t(X;18), and no defining immunohistochemical or electron microscopic features represent an as yet unrecognized part of a spectrum that spans from synovial sarcoma to MPNST or other spindle cell tumors?

[Biphasic hypopharyngeal synovial sarcoma: ultrastructural, cytofluorometric and immunohistochemical study and brief review of the literature]. / Sarcoma sinoviale bifasico a localizzazione ipofaringea: studio ultrastrutturale, citofluorometrico ed immunoistochimico e breve revisione della Letteratura.

Synovial sarcomas account for 7-10% of all soft tissue malignancies and the rare head and neck region location accounts for an average 5% of them. A brief review of the data in the Literature has shown that not more than one hundred cases of cervical-facial synovial sarcoma have been reported. In the head and neck locations this form of tumor is significantly less aggressive, with a higher survival rate and a recurrence rate much lower than the 60-70% shown for other locations in the limbs. After a brief review of the Literature, Authors present a rare clinical case of hypopharyngeal synovial sarcoma which recently came under observation. Despite the accurate diagnostic procedure, after surgical removal of the tumor by CO2 laser microlaryngoscopy, diagnosis required the use of histological and ultrastructural techniques. CT and NMR of the neck using contrast medium showed that the structure of the neoformation was similar to that of the soft tissues, it was 3-4 cm in diameter, located in the hypopharynx and had an extensive surface in contact with the left glossoepiglottic groove. The lesion appeared to involve the free edge of the aryepiglottic fold, coming into contact with the free edge of the epiglottis; it could not be dissociated form the epiglottis and obliterated both the homolateral glossoepiglottic vallecula and the pyriform sinus. Structural analysis after radiography with a contrast medium showed a marked impregnation of the lesion, indicative of high degree of vascolarization. Ultrastructural, cytofluormetric and immunohistochemical analyses were performed on the neoplasm in order to process all these data together with the clinical parameters; in other words a multi-parameter evaluation was performed, as suggested by other Authors, to determine the therapy and arrange more accurate monitoring of this patient, victim of a neoplasm with a high potential for metastases.

Role of electron microscopy in the evaluation of soft tissue neoplasms, with emphasis on spindle cell and pleomorphic tumors.

The current significant role of transmission electron microscopy in the evaluation of soft tissue tumors when correlated with conventional histological and immunohistochemical studies is discussed for the following entities: myxofibrosarcoma, storiform-pleomorphic fibrosarcoma (malignant fibrous histiocytoma), and myofibrosarcoma; dermatofibrosarcoma protuberans; hemangiopericytoma; monophasic synovial sarcoma; extrarenal rhabdoid tumor; soft tissue perineurioma; and gastrointestinal stromal tumors, notably the so-called autonomic nerve variant.

Translocation (X;18) in a biphasic synovial sarcoma with morphologic features of neural differentiation.

The authors report a recurred neoplasm showing distinctive histologic, immunophenotypic, and ultrastructural features characteristic of biphasic synovial sarcoma with neural differentiation. The features include areas with a growth pattern of densely packed spindle cells in irregularly intersecting, broad fascicles, diffuse vimentin and HBA 71 immunoreactivity, expression of S-100 protein, and other neural markers. Moreover, areas with glandular structures and cellular expression of cytokeratin and epithelial membrane antigen were noted. Additionally, areas of neural-like growth pattern were positive for neuron-specific enolase, HNK-1, and protein gene product 9.5. Furthermore, cytogenetic analysis, two-color interphase fluorescence in situ hybridization, and reverse transcription polymerase chain reaction demonstrated the reciprocal translocation between chromosomes X and 18 associated with the different subtypes of tumor cells. The establishment and characterization of the tumor cell line are detailed. This cell line retains the distinct morphologic and genetic characteristics of the original biphasic synovial sarcoma with neural differentiation.

Cytologic features of synovial sarcoma with emphasis on the monophasic fibrous variant: a morphologic and immunocytochemical analysis of bcl-2 protein expression.

BACKGROUND: Monophasic fibrous synovial sarcoma (SS) is the most common variant of SS but few cytologic studies concerning this entity are available. bcl-2 protein immunoexpression has been described as a characteristic marker of SS and is useful for its differentiation from other sarcomas. METHODS: Twelve cytologic specimens from 11 patients with histologically proven SS were reexamined. Ten samples were obtained by fine-needle aspiration and in two cases fluid from cystic tumoral areas was obtained at surgery. Nine cases corresponded to monophasic fibrous tumors and two to biphasic tumors. Immunoexpression of bcl-2 was evaluated in all histologic specimens and in six cytologic samples. bcl-2 protein also was evaluated in 13 soft tissue tumors. RESULTS: All cytologic specimens had a similar appearance. Most smears were highly cellular and were comprised of densely packed, tridimensional groups and numerous isolated, round to oval cells. Remarkable findings included cellular monomorphism and vascular structures within the cell groups. Only one case showed cytologic evidence of epithelial differentiation. Immunoexpression of bcl-2 protein was present in 10 of the 11 histologic specimens (90.9%) and in 5 of the 6 cytologic samples (83.3%). A positive result also was observed in malignant fibrous histiocytoma, dermatofibrosarcoma protuberans, infantile hemangiopericytoma, pleomorphic liposarcoma, and malignant solitary fibrous tumor. CONCLUSIONS: Although cytomorphologic features of SS are characteristic enough to permit its recognition, clinical correlation is necessary for its correct diagnosis. The immunoexpression of bcl-2 protein is not specific of SS and other soft tissue tumors can show a similar positive reaction.

Radiation-associated synovial sarcoma.

We describe a case of synovial sarcoma occurring in a 36 year-old woman, 8 years after radiation therapy for Hodgkin's disease. The tumor showed histological, immunohistochemical, ultrastructural, and molecular features diagnostic of synovial sarcoma. To our knowledge, this is the first report of a fully documented case of radiation associated synovial sarcoma.