A renal cell carcinoma with EWSR1‐TFE3 fusion gene

Both EWSR1 and TFE3 are well‐known oncogenes. EWSR1 encodes an RNA‐binding protein involved in multiple soft tissue tumors, including Ewing's sarcoma/peripheral neuroectodermal tumor, desmoplastic small round cell tumor, soft tissue clear cell sarcoma (malignant melanoma of soft parts), extraskeletal myxoid chondrosarcoma, and myxoid liposarcomas. TFE3 regulates both Golgi and lysosomal homeostasis and is rearranged in renal cell carcinoma (RCC), alveolar soft part sarcoma, epithelioid hemangioendothelioma, and perivascular epitheloid cell tumors (PEComas). In this report, we found a rare case of RCC with a fusion between 5′ EWSR1 and 3′ TFE3. The fusion product retained most functional motifs of TFE3. The oncogenic mechanism likely involves TFE3 overexpression through its juxtaposition with the regulatory elements of EWSR1 and its translocation to the nucleus, resulting in the deregulation of Golgi and lysosomal homeostasis. This is a second case of RCC containing EWSR1‐TFE3 fusion.     

EWSR1‐POU5F1 fusion in soft tissue myoepithelial tumors. A molecular analysis of sixty‐six cases,including soft tissue,bone, and visceral lesions,showing common involvement of the EWSR1 gene

The diagnosis of myoepithelial (ME) tumors outside salivary glands remains challenging, especially in unusual clinical presentations, such as bone or visceral locations. A few reports have indicated EWSR1 gene rearrangement in soft tissue ME tumors, and, in one case each, the fusion partner was identified as either PBX1 or ZNF444. However, larger studies to investigate whether these genetic abnormalities are recurrent or restricted to tumors in soft tissue locations are lacking. Sixty‐six ME tumors mainly from soft tissue (71%), but also from skin, bone, and visceral locations, characterized by classic morphological features and supporting immunoprofile were studied. Gene rearrangements in EWSR1, FUS, PBX1, and ZNF444 were investigated by fluorescence in situ hybridization. EWSR1 gene rearrangement was detected in 45% of the cases. A EWSR1‐POU5F1 fusion was identified in a pediatric soft tissue tumor by 3′Rapid Amplification of cDNA Euds (RACE) and subsequently confirmed in four additional soft tissue tumors in children and young adults. An EWSR1‐PBX1 fusion was seen in five cases, whereas EWSR1‐ZNF444 and FUS gene rearrangement was noted in one pulmonary tumor each. In conclusion, EWSR1 gene rearrangement is a common event in ME tumors arising outside salivary glands, irrespective of anatomical location. EWSR1‐negative tumors were more often benign, superficially located, and showed ductal differentiation, suggesting the possibility of genetically distinct groups. A subset of soft tissue ME tumors with clear cell morphology harbor an EWSR1‐POU5F1 fusion, which can be used as a molecular diagnostic test in difficult cases. These findings do not support a pathogenetic relationship between soft tissue ME tumors and their salivary gland counterparts. © 2010 Wiley‐Liss, Inc.     

t(19;22)(q13;q12) Translocation leading to the novel fusion gene EWSR1‐ZNF444 in soft tissue myoepithelial carcinoma

Myoepithelial neoplasms of soft tissue have only recently been acknowledged as a separate diagnostic entity. To know based on histological appearance whether these tumors are benign or malignant is often difficult, and their tumorigenic mechanisms remain poorly understood. We report a myoepithelial carcinoma with an aberrant near‐diploid karyotype, 43～47,XX,add(1)(p34)x2,add(3)(q27)x2,del(12)(q22),+add(18)(p11)x2,del(22)(q11),+r, found in cells cultured from a lung metastasis. The deletion in 22q led us to search by molecular cytogenetic means for possible EWSR1 rearrangements, and eventually a novel chimeric gene consisting of the 5′‐end of EWSR1 (22q12) and the 3′‐end of ZNF444 (19q13) was found. How the new fusion gene contributes to tumorigenesis is unknown, but the finding of an EWSR1 rearrangement suggests that this, possibly even the EWSR1‐ZNF444, is a defining pathogenetic feature of at least a subset of these tumors. © 2009 Wiley‐Liss, Inc.     

Secondary EWSR1 gene abnormalities in SMARCB1‐deficient tumors with 22q11‐12 regional deletions: Potential pitfalls in interpreting EWSR1 FISH results

SMARCB1 inactivation occurs in a variety of tumors, being caused by various genetic mechanisms. Since SMARCB1 and EWSR1 genes are located close to each other on chromosome 22, larger SMARCB1 deletions may encompass the EWSR1 locus. Herein, we report four cases with SMARCB1‐deletions showing concurrent EWSR1 gene abnormalities by FISH, which lead initially to misinterpretations as EWSR1‐rearranged tumors. Our study group included various morphologies: a poorly differentiated chordoma, an extrarenal rhabdoid tumor, a myoepithelial carcinoma, and a proximal‐type epithelioid sarcoma. All cases showed loss of SMARCB1 (INI1) by immunohistochemistry (IHC) and displayed characteristic histologic features for the diagnoses. The SMARCB1 FISH revealed homozygous or heterozygous deletions in three and one case, respectively. The co‐hybridized EWSR1 probes demonstrated either unbalanced split signals or heterozygous deletion in two cases each. The former suggested bona fide rearrangement, while the latter resembled an unbalanced translocation. However, all the FISH patterns were quite complex and distinct from the simple and uniform split signals seen in typical EWSR1 rearrangements. We conclude that in the context of 22q11‐12 regional alterations present in SMARCB1‐deleted tumors, simultaneous EWSR1 involvement may be misinterpreted as equivalent to EWSR1 rearrangement. A detailed clinicopathologic correlation and supplementing the EWSR1 FISH assay with complementary methodology is mandatory for correct diagnosis. © 2016 Wiley Periodicals, Inc.     

Metastatic sporadic paraganglioma with EWSR1::CREM gene fusion: A unique molecular profile that expands the phenotypic diversity of the molecular landscape of the EWSR1::CREM gene fusion positive tumors

Chromosomal translocations with gene fusions are uniquely rare events in paraganglioma, mostly involving UBTF::MAML3 gene fusion. Precedent literature suggests that tumors involving MAML3 gene fusion correlate with poor clinical outcomes. Herein, we report a case of metastatic sporadic paraganglioma harboring EWSR1::CREM gene fusion in a 36-year-old male, that has not been previously described. The patient presented with large paraspinal mass that was resected the same year. Tumor recurred 3-years later and on further work-up, patient was found to have metastases involving both lungs. Histopathologic evaluation of the original primary tumor showed tightly packed irregular nests and cords of cells containing palely eosinophilic cytoplasm. Features considered atypical included: areas of solid growth pattern, coagulative tumor necrosis, focal cellular atypia and angiolymphatic invasion were also identified. By immunohistochemistry, the tumor cells were positive for synaptophysin and chromogranin and negative for keratin. The S100 stain highlights the sustentacular cells and the Ki-67 proliferation index of 15%. The recurrence specimen was similar but showed increased cellularity, atypia, necrosis, and proliferative activity (Ki-67 proliferation index of 35%). CT guided biopsy of the right lung lesion was consistent with metastasis. Next generation sequencing identified EWSR1::CREM fusion. The breakpoints were found in chromosome 22: 29683123 for EWSR1 exon 7 (NM_005243.3) and at chromosome 10:35495823 for CREM exon 6 (NM_001267562.1). Fluorescence in situ hybridization for EWSR1 gene rearrangement was positive. In summary, we report a case of metastatic paraganglioma with EWSR1::CREM gene fusion, not previously described in this entity, and expands on the phenotypic diversity within the genetic landscape of EWSR1::CREM gene fusion positive tumors.     

A novel low‐grade nasopharyngeal adenocarcinoma characterized by a GOLGB1‐BRAF fusion gene

Nasopharyngeal adenocarcinoma is a rare malignancy that is classified into conventional/surface‐ and salivary‐types. Herein we report the case of a 52‐year‐old male who presented with a right nasopharyngeal mass and right‐sided hearing loss. Diagnostic imaging revealed a circumscribed 1.7 cm mass centred in the right antero‐lateral aspect of the nasopharynx. A biopsy showed a gland‐forming neoplasm that was in continuity with the surface epithelium. The tumor exhibited a nested to micro‐papillary architecture, with mild cytologic atypia. Immunohistochemistry demonstrated diffuse staining for CK7, SOX10, and p16; the abluminal layer was highlighted by CK5 and p63, while the luminal cells expressed CD117. The tumor was not amenable to subclassification and was diagnosed as a low‐grade nasopharyngeal adenocarcinoma, not otherwise specified (NOS). Subsequent RNA sequencing was performed which identified a novel GOLGB1‐BRAF fusion product. Based on its unique morphology and molecular findings, this is presumed to represent a novel subtype of nasopharyngeal adenocarcinoma. In addition to being of diagnostic relevance, this fusion may ultimately represent a potential therapeutic target.     

伴EWSR1-CREB1融合的颅内黏液样间叶性肿瘤1例

颅内黏液样间叶性肿瘤是一种罕见的肿瘤,分子遗传学伴EWSR1与CREB家族基因融合。本文报道1例9岁男性患儿,小脑占位性病变,肿瘤结节状生长,界限清楚,肿瘤细胞椭圆形、梭形或星芒状,疏密不等,大部分呈条索状或疏松网状分布于黏液性间质中,间质内可见“石棉样”纤维,局灶细胞较丰富,呈片状排列。免疫组织化学结果：波形蛋白阳性...     

A morphologic and molecular reappraisal of myoepithelial tumors of soft tissue,bone, and viscera with EWSR1 and FUS gene rearrangements

Myoepithelial tumors (MET) represent a clinicopathologically heterogeneous group of tumors, ranging from benign to highly aggressive lesions. Although MET arising in soft tissue, bone, or viscera share morphologic and immunophenotypic overlap with their salivary gland and cutaneous counterparts, there is still controversy regarding their genetic relationship. Half of MET of soft tissue and bone harbor EWSR1 or FUS related fusions, while MET arising in the salivary gland and skin often show PLAG1 and HMGA2 gene rearrangements. Regardless of the site of origin, the gold standard in diagnosing a MET relies on demonstrating its “myoepithelial immunophenotype” of positivity for EMA/CK and S100 protein or GFAP. However, the morphologic spectrum of MET in soft tissue and bone is quite broad and the above immunoprofile is nonspecific, being shared by other pathogenetically unrelated neoplasms. Moreover, rare MET lack a diagnostic immunoprofile but shows instead the characteristic gene fusions. In this study, we analyzed a large cohort of 66 MET with EWSR1 and FUS gene rearrangements spanning various clinical presentations, to better define their morphologic spectrum and establish relevant pathologic‐molecular correlations. Genetic analysis was carried out by FISH for EWSR1/FUS rearrangements and potential partners, and/or by targeted RNA sequencing. Then, 82% showed EWSR1 rearrangement, while 18% had FUS abnormalities. EWSR1‐POU5F1 occurred with predilection in malignant MET in children and young adults and these tumors had nested epithelioid morphology and clear cytoplasm. In contrast, EWSR1/FUS‐PBX1/3 fusions were associated with benign and sclerotic spindle cell morphology. Tumors with EWSR1‐KLF17 showed chordoma‐like morphology. Our results demonstrate striking morphologic‐molecular correlations in MET of bone, soft tissue and viscera, which might have implications in their clinical behavior.     

Paternal mosaicism for a novel PBX1 mutation associated with recurrent perinatal death: Phenotypic expansion of the PBX1‐related syndrome

Autosomal dominant (de novo) mutations in PBX1 are known to cause congenital abnormalities of the kidney and urinary tract (CAKUT), with or without extra‐renal abnormalities. Using trio exome sequencing, we identified a PBX1 p.(Arg107Trp) mutation in a deceased one‐day‐old neonate presenting with CAKUT, asplenia, and severe bilateral diaphragmatic thinning and eventration. Further investigation by droplet digital PCR revealed that the mutation had occurred post‐zygotically in the father, with different variant allele frequencies of the mosaic PBX1 mutation in blood (10%) and sperm (20%). Interestingly, the father had subclinical hydronephrosis in childhood. With an expected recurrence risk of one in five, chorionic villus sampling and prenatal diagnosis for the PBX1 mutation identified recurrence in a subsequent pregnancy. The family opted to continue the pregnancy and the second affected sibling was stillborn at 35 weeks, presenting with similar severe bilateral diaphragmatic eventration, microsplenia, and complete sex reversal (46, XY female). This study highlights the importance of follow‐up studies for presumed de novo and low‐level mosaic variants and broadens the phenotypic spectrum of developmental abnormalities caused by PBX1 mutations.     

Six novel β‐galactosidase gene mutations in Brazilian patients with GM1‐gangliosidosis

GM1‐gangliosidosis is a lysosomal storage disease caused by a deficiency of acid β‐galactosidase. Three clinical forms are recognized—infantile, juvenile, and adult—based on age of onset and severity of the symptoms. We have performed molecular analysis of a large cohort of GM1 patients (19 Brazilian and one Uruguayan), using nonradioactive single‐strand conformation polymorphism (SSCP) and restriction enzyme analysis of genomic DNA. Six novel mutations (R121S, V240M, D491N, 638–641insT, 895–896insC, 1622–1627insG) and two previously described point mutations (R59H, R208C) were identified. Together they accounted for 90% of the disease alleles of the patients. Two mutations, 1622–1627insG and R59H, were present in 18 of 20 patients. In addition, four polymorphisms (L10P, L12L, R521C, S532G) were identified. All cases reported are infantile GM1 gangliosidosis. This report constitutes the most comprehensive molecular study to date of this disorder in infantile patients. Since GM1‐gangliosidosis is the most common lysosomal storage disorder in Southern Brazil, molecular diagnosis will be important for genetic counseling, carrier detection and prenatal diagnosis in index families. Hum Mutat 13:401–409, 1999. © 1999 Wiley‐Liss, Inc.