The expanding morphological and genetic spectrum of MYOD1-mutant spindle cell/sclerosing rhabdomyosarcomas: a clinicopathological and molecular comparison of mutated and non-mutated cases.

AIMS: Spindle cell/sclerosing rhabdomyosarcomas (SC/SRMS) feature spindled and/or rounded rhabdomyosarcomatous cells within variably hyalinised stroma. Only 30-67% of SC/SRMSs harbour neomorphic MYOD1 p.L122R mutations, indicating heterogeneity in this RMS type. We compared MYOD1-mutant and non-mutant cases to characterise the histological and genetic spectrum of mutated SC/SRMS. METHODS AND RESULTS: Seventeen RMSs with spindled, sclerosing or hybrid histology were sequenced to identify MYOD1 and PIK3CA mutations and reappraised to assess histological features and myogenic immunophenotypes. Twelve SC/SRMSs harboured MYOD1 mutations, including homozygous p.L122R (n = 8), heterozygous p.L122R (n = 3) and heterozygous p.E118K (n = 1). MYOD1-mutant tumours affected nine females and three males aged 8-64 years (median = 22.5), had a median size of 4.2 cm (range = 2-22) and involved the head and neck (n = 7), extremities (n = 4) and mediastinum (n = 1). Fascicular/spindle histology was predominant in four cases, including one with heterologous lipoblasts in focally myxoid stroma. Four sclerosing cases mainly comprised rounded cells, including one with multinucleated tumour cells. Four cases were histologically hybrid. The only PIK3CA (p.H1047R) mutation was detected in a predominantly spindled MYOD1-p.L122R-mutated case, but not in its laser-microdissected lipoblast-containing area. All MYOD1-mutant cases exhibited diffuse MYOD1 expression but patchy myogenin reactivity. At final follow-up (median = 13.5 months), recurrences (n = 4), metastases (n = 2) or both (n = 1) occurred in seven MYOD1-mutant cases; one had died of disease. Five non-mutated cases were reclassified as spindle embryonal (n = 3), dense embryonal (n = 1) and unclassifiable (n = 1) RMSs. CONCLUSION: MYOD1-mutant RMSs are uncommonly mutated with PIK3CA and behave aggressively with an expanded morphological and genetic spectrum, including lipoblastic differentiation, multinucleated cells and the alternative p.E118K mutation.

Paratesticular Fibrous Pseudotumor: A New Entity of IgG4-Related Disease?

INTRODUCTION: Paratesticular fibrous pseudotumor (PFP) represents a benign tumor-like lesion confined to intrascrotal, paratesticular areas. Due to its rarity, only less than 200 cases have been reported to date, of which both pathogenesis and clinical management are little understood. Recently, PFP has been postulated to be among the spectrum of so-called immunoglobulin G4-related diseases (IgG4-RD). Here we describe a case of PFP focusing on the clinical, morphological features and the utility of immunohistochemistry to support the theory that PFP might be a potential member of IgG4-RD family. CASE PRESENTATION: A 41-year-old man presented with a slowly growing, right intrascrotal mass An MRI scan revealed a diffuse-proliferative nodular mass around the paratesticular area. The patient underwent right orchiectomy and a diffuse multinodular tumor with testicular compression was discovered without intratesticular infiltration. Postoperatively, the patient has been well for 2 years up to the recent follow up. On histological examination, the lesion consisted of hyalinized fibrotic tissue with storiform patterns. There were scattered germinal centers; lymphocytic vasculitis was also noted. The immunoglobulin G4 staining showed infiltration of positive plasma cells with highest count 52 per high-power field, whereas the mixed Kappa and Lambda immunoglobulin light chain expression indicated the polyclonality of the plasma cell population. CONCLUSIONS: The morphological and immunohistochemical features in our case support the theory of PFP being part of IgG4-RD. Familiarity to this tumor-like lesion is crucial, since it may respond to corticosteroid therapy, which may save patients from more aggressive surgical procedures.

First cloned human immortalized adipose derived mesenchymal stem-cell line with chimeric SS18-SSX1 gene (SS-iASC).

The SS18-SSX chimeric gene is unique to synovial sarcoma. Multiple model systems including mouse cell lines expressing SS18-SSX, and genetically engineered mouse models of synovial sarcoma have been developed to elucidate the role of the chimeric gene in synovial sarcomagenesis. Although several cell lines stably expressing human SS18-SSX exist, there is an ongoing need for cell culture models enabling researchers to investigate the molecular mechanism of SS18-SSX action in a relevant cellular context. Here we report the establishment of a novel SS18-SSX1-expressing cell line created from immortalized human adipose tissue-derived mesenchymal stem cells via lentiviral transduction of the chimeric gene. Our cell line, termed SS-iASC, has been characterized by karyotyping and cell line identification, and stable expression of SS18-SSX1 has been verified using real-time PCR (RT-PCR), nested PCR, immunofluorescence, and immunoblotting. Focal cytokeratin positivity characteristic of synovial sarcoma but no ß-Catenin, Bcl-2 or cyclin D1 expression was observed in SS-iASC. The novel cell line expressing SS18-SSX1 on a human adipose-derived stromal cell background is expected to be helpful in addressing the question whether the chimeric gene alone is sufficient to trigger the formation of synovial sarcoma.

Morphological and microcirculatory evaluation of the rat testis after detorsion with or without a capsular release with a tunica vaginalis flap.

Testicular torsion may lead to serious ischemia, and the viability depends on the duration of torsion and the effect of ischemia-reperfusion. Testicular decompression and tunica vaginalis flap application technique were introduced in 2008 by Kutikov et al. We aimed to examine the impact of this method on the testicular microcirculation and hemorheological parameters in a rat model. Six adult rats underwent bilateral scrotal exploration. Intravaginal torsion of the testis was created by 720° rotation on both sides for 2 h. After detorsion, the right testes underwent tunica albuginea incision and tunica vaginalis flap application. Testicular microcirculation was monitored and hematological parameters, erythrocyte deformability, and aggregation were determined. Measurements were performed before and after torsion, directly after detorsion, on the 1 st -2 nd and 8 th postoperative day. After the last sampling, testicles were removed to determine their volume for histological examinations. The microcirculatory parameters demonstrated slight differences between testicles. Apical zone of the left (nondecompressed) testicles had elevated compared to the middle zone (P < 0.05). On the 2 nd and 8 th day, the microcirculation of the testes normalized but not equally. The erythrocyte aggregation and deformability decreased by the 8 th day. Both testicles underwent atrophy and epithelial necrosis, but the volume of the decompressed ones was lower (1.07 ± 0.08 vs 1.25 ± 0.31). Histologically, there was no significant difference in epithelial damage score between decompressed and nondecompressed testes. In conclusion, 2-h ischemia led to alteration in testicular microcirculation, reduction in volume, changes in hemorheological parameters and serious epithelial necrosis both in decompressed and nondecompressed testicles without remarkable differences.

Pleomorphic hyalinizing angiectatic tumor of soft parts: case report with unusual ganglion-like cells and review of the literature.

Pleomorphic hyalinizing angiectatic tumor (PHAT) is a recently described, non-metastasizing tumor of uncertain lineage. This tumor distributes equally between the genders and has a predilection for the subcutaneous soft tissue, particularly in lower extremity, other locations are rare. Based on the recent literature, PHAT is suspected to encompass the morphological spectrum with other tumors such as myxoinflammatory fibroblastic sarcoma (MIFS) and hemosiderotic fibrolipomatous tumor (HFLT), although cytogenetic data remain inconsistent. We report a case of PHAT that arose in the upper arm with unusual morphology which showed ganglion-like cells similar to Reed-Sternberg-like cells found in MIFS. The tumor had strong immunohistochemical expression of CD34, CD99, and was negative for S-100. The ganglion-like cells were positive for both CD34 and CD68 but negative for CD30. The translocation between chromosome 1 and 10, a frequent finding of MIFS and HFLT, was not identified by FISH excluding the possibility of hybrid PHAT and MIFS. We conclude FISH can be a potential useful tool to separate PHAT with atypical morphology from hybrid tumor in doubted cases. Due to the rarity of PHAT and lack of consistent pathogenetic signatures, more cases and further studies will be needed to elucidate the pathogenesis and nature of this tumor.

Absence of estrogen receptor alpha (ESR1) gene amplification in a series of breast cancers in Taiwan.

Immunohistochemical expression of ERα, encoded by the ESR1 (estrogen receptor 1) gene located at 6q25.1, is the most important determinant of responsiveness to endocrine therapy in breast cancer. The prevalence and significance of ESR1 amplification in breast cancer remain controversial. We set out to assess ESR1 status and its relevance in breast cancer in Taiwan. We tested tissue samples from 311 invasive carcinomas in a tissue microarray for ESR1 status by fluorescent in situ hybridization (FISH) and chromogenic in situ hybridization (CISH). In order to examine its association with ERα and ESR1 status, HER2 status was determined by FISH. Of the carcinomas, 58.8 % (183/311) was ERα positive. None of the carcinomas showed amplification of ESR1 by either method, whereas 24.1 % (75/311) of the carcinomas harbored HER2 amplification. Of the carcinomas, 9.6 % (26/301) showed ESR1 gain (1.3 ≤ ratio ESR1/chromosome 6 < 2) by FISH and 10 % (24/299) by CISH. FISH and CISH results showed a good correlation (κ-coefficient = 0.786). ESR1 gain by FISH and CISH was significantly associated with high-grade (P = 0.0294 and 0.0417, respectively) but not with ERα expression, HER2 status, or overall survival. ERα positivity was significantly associated with better overall survival (P = 0.039). HER2 amplification was significantly related with poor overall survival (P = 0.002). Our data confirm that in breast cancer, HER2 amplification is a frequent genetic aberration and a negative prognostic factor, and show that ESR1 amplification is not a key genetic abnormality in the tumorigenesis of breast cancer in Taiwan.

SMARCB1 protein and mRNA loss is not caused by promoter and histone hypermethylation in epithelioid sarcoma.

About 10% of epithelioid sarcomas have biallelic mutation of the SMARCB1 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily b, member 1) gene resulting in a lack of this nuclear protein. It has been suggested that SMARCB1 may be silenced by epigenetic changes in the remaining 90% of tumors. Thus, we hypothesized that the promoter of SMARCB1 is hypermethylated. We also examined SMARCB1 mRNA level to determine if a post-translational change was possible. Thirty-six cases of epithelioid sarcomas were studied. Immunohistochemistry and mutation analysis of the SMARCB1 gene were performed to select appropriate cases. Methylation status was assessed by methylation-specific PCR. Laser capture microdissection of tumor cells followed by real-time PCR was applied to examine the expression of SMARCB1 mRNA. Of 36 epithelioid sarcomas, 31 (86%) displayed a lack of SMARCB1 nuclear protein. In all, 4 (13%) of 31 SMARCB1-negative cases harbored biallelic deletion while 9 (33%) cases showed single-allelic deletion. One (4%) frameshift deletion of exon 3 and one point mutation of exon 7 were also found. In 16 (59%) cases, both alleles were intact. Altogether, 25/31 (81%) SMARCB1-negative cases had at least one intact allele. None of these cases demonstrated promoter hypermethylation. Low levels of SMARCB1 mRNA were found in all cases with tumor tissue extracted RNA (because of the minimal normal cell contamination) but no mRNA could be detected in laser dissected cases (containing only tumor cells). Enhancer of zeste homolog 2 (EZH2) overexpression was not characteristic of epithelioid sarcoma. Thus, loss of SMARCB1 expression in epithelioid sarcoma is caused neither by DNA hypermethylation nor by post-translational modifications. Most likely it is the microRNA destruction of SMARCB1 mRNA but further investigations are needed to elucidate this issue.

Poorly differentiated synovial sarcoma is associated with high expression of enhancer of zeste homologue 2 (EZH2).

BACKGROUND: Enhancer of zeste homologue 2 (EZH2) is a polycomb group (PcG) family protein. Acting as a histone methyltransferase it plays crucial roles in maintaining epigenetic stem cell signature, while its deregulation leads to tumor development. EZH2 overexpression is commonly associated with poor prognosis in a variety of tumor types including carcinomas, lymphomas and soft tissue sarcomas. However, although the synovial sarcoma fusion proteins SYT-SSX1/2/4 are known to interact with PcG members, the diagnostic and prognostic significance of EZH2 expression in synovial sarcoma has not yet been investigated. Also, literature data are equivocal on the correlation between EZH2 expression and the abundance of trimethylated histone 3 lysine 27 (H3K27me3) motifs in tumors. METHODS: Immunohistochemical stains of EZH2, H3K27me3, and Ki-67 were performed on tissue microarrays containing cores from 6 poorly differentiated, 39 monophasic and 10 biphasic synovial sarcomas, and evaluated by pre-established scoring criteria. Results of the three immunostainings were compared, and differences were sought between the histological subtypes as well as patient groups defined by gender, age, tumor location, the presence of distant metastasis, and the type of fusion gene. The relationship between EZH2 expression and survival was plotted on a Kaplan-Meier curve. RESULTS: High expression of EZH2 mRNA and protein was specifically detected in the poorly differentiated subtype. EZH2 scores were found to correlate with those of Ki-67 and H3K27me3. Cases with high EZH2 score were characterized by larger tumor size (≥ 5cm), distant metastasis, and poor prognosis. Even in the monophasic and biphasic subtypes, higher expression of EZH2 was associated with higher proliferation rate, larger tumor size, and the risk of developing distant metastasis. In these histological groups, EZH2 was superior to Ki-67 in predicting metastatic disease. CONCLUSIONS: High expression of EZH2 helps to distinguish poorly differentiated synovial sarcoma from the monophasic and biphasic subtypes, and it is associated with unfavorable clinical outcome. Importantly, high EZH2 expression is predictive of developing distant metastasis even in the better-differentiated subtypes. EZH2 overexpression in synovial sarcoma is correlated with high H3K27 trimethylation. Thus, along with other epigenetic regulators, EZH2 may be a future therapeutic target.

A challenging case of metastatic intra-abdominal synovial sarcoma with unusual immunophenotype and its differential diagnosis.

The primary and metastatic gastrointestinal synovial sarcoma is rare with a wide differential diagnosis. It usually expresses cytokeratins EMA, BCL2 with an occasional CD99, and S100 positivity but not desmin. We present a case of metastatic synovial sarcoma with unusual immunophenotype causing diagnostic challenges. The tumor cells showed focal cytokeratin, EMA, and, unexpectedly, desmin positivity. Additional intranuclear TLE-1 positivity and negativity for CD34 and DOG-1 were also identified. A diagnosis of monophasic synovial sarcoma was confirmed by using FISH break-apart probe. RT-PCR revealed the SYT-SSX1 fusion gene. Intra-abdominal synovial sarcoma, either primary or metastatic, with unusual desmin positivity raises the diagnostic challenge, since a wide range of differential diagnoses could show a similar immunophenotype (leiomyosarcoma, desmoid tumor, myofibroblastic tumor, and rarely GIST etc.). Typical morphology and focal cytokeratin/EMA positivity should alert to this tumor, and FISH and RT-PCR remain the gold standard for the confirmation.

Gonadoblastoma: Case report of two young patients with isochromosome 12p found in the dysgerminoma overgrowth component in one case.

Gonadoblastomas are unusual neoplasias that frequently appear in the dysgenetic gonads of women with chromosome Y anomaly. We present two cases of gonadoblastoma associated with complete gonadal dysgenesis and Turner syndrome, respectively, with dysgerminoma overgrowth found in one case. We were interested in the DNA ploidy, the presence of Y chromosome DNA sequence and the status of chromosome 12p arm among the tumor cells. We performed cytophotometry to analyze the DNA content and fluorescence in situ hybridization (FISH) to identify the Y chromosome and the isochromosome 12p within the tumor cells. The cytophotometric result showed diploid DNA content in gonadoblastoma, whereas dysgerminoma revealed aneuploid DNA. The FISH result revealed Y chromosome DNA sequence within gonadoblastoma and dysgerminoma. Isochromosome 12p was identified in dysgerminoma, but not in gonadoblastoma. We conclude that gonadoblastoma and dysgerminoma have a strong association with the Y chromosome, and dysgerminoma overgrowth is due to further chromosomal aberrations, such as isochromosome 12p. Histological, immunohistocheimcal and molecular studies should render the correct diagnosis. Identifying dysgerminoma overgrowth is crucial since it is associated with adverse prognosis and requires additional therapy.

De novo malignant solitary fibrous tumor of the kidney.

The kidney is a relatively infrequent site for solitary fibrous tumor (SFT). Among the previously reported cases, only two cases of malignant renal SFT developing via dedifferentiation from a pre-existing benign SFT have been reported. Here we reported a case of de novo malignant renal SFT clinically diagnosed as renal cell carcinoma in a 50-year-old woman. The tumor was circumscribed but unencapsulated and showed obvious hemorrhagic necrosis. Microscopically, the tumor was composed of patternless sheets of alternating hypercellular and hypocellular areas of spindle cells displaying mild to moderate nuclear atypia, frequent mitoses up to 8 per 10 high power fields, and a 20% Ki-67 proliferative index. Immunohistochemical studies revealed reactivity for CD34, CD99 and vimentin, with no staining for all other markers, confirming the diagnosis of SFT. No areas of dedifferentiation were seen after extensive sampling. Based on the pathologic and immunohistochemical features, a diagnosis of de novo malignant renal SFT was warranted. Our report expands the spectrum of malignant progression in renal SFTs. Even though this patient has been disease-free for 30 months, long-term follow-up is still mandatory.