An Unusual Endometrial Stromal Neoplasm With JAZF1-BCORL1 Rearrangement.

Endometrial stromal tumors represent the second most common category of uterine mesenchymal tumors. Several different histologic variants and underlying genetic alterations have been recognized, one such being a group associated with BCORL1 rearrangements. They are usually high-grade endometrial stromal sarcomas, often associated with prominent myxoid background and aggressive behavior. Here, we report an unusual endometrial stromal neoplasm with JAZF1-BCORL1 rearrangement and briefly review the literature. The neoplasm formed a well-circumscribed uterine mass in a 50-yr-old woman and had an unusual morphologic appearance that did not warrant a high-grade categorization. It was characterized by a predominant population of epithelioid cells with clear to focally eosinophilic cytoplasm growing in interanastomosing cords and trabeculae set in a hyalinized stroma as well as nested and fascicular growths imparting focal resemblance to a uterine tumor resembling ovarian sex-cord tumor, PEComa, and a smooth muscle neoplasm. A minor storiform growth of spindle cells reminiscent of the fibroblastic variant of low-grade endometrial stromal sarcoma was also noted but conventional areas of low-grade endometrial stromal neoplasm were not identified. This case expands the spectrum of morphologic features seen in endometrial stromal tumors, especially when associated with a BCORL1 fusion and highlights the utility of immunohistochemical and molecular techniques in the diagnosis of these tumors, not all of which are high grade.

Endometrial stromal tumors of the uterus: Epidemiology, pathological and biological features, treatment options and clinical outcomes.

Endometrial stromal tumors (EST) are uterine mesenchymal tumors, which histologically resemble endometrial stroma of the functioning endometrium. The majority of EST are malignant tumors classified as low-grade endometrial stromal sarcoma (LG-ESS), high-grade endometrial stromal sarcoma (HG-ESS), and undifferentiated uterine sarcoma (UUS). Overall, ESTs are rare malignancies, with an annual incidence of approximately 0.30 per 100'000 women, mainly affecting peri- or postmenopausal women. The most common genetic alteration identified in LG-ESS is the JAZF1-SUZ12 rearrangement, while t(10;17)(q23,p13) translocation and BCOR gene abnormalities characterize two major subtypes of HG-ESS. The absence of specific genetic abnormalities is the actual hallmark of UUS. Unlike HG-ESSs, LG-ESSs usually express estrogen and progesterone receptors. Total hysterectomy without morcellation and bilateral salpingo-oophorectomy (BSO) is the first-line treatment of early-stage LG-ESS. Ovarian preservation, fertility-sparing treatment, and adjuvant hormonal therapy ± radiotherapy may be an option in selected cases. In advanced or recurrent LG-ESS, surgical cytoreduction followed by hormonal treatment, or vice versa, are acceptable treatments. The standard treatment for apparently early-stage HG-ESS and UUS is total hysterectomy without morcellation with BSO. Ovarian preservation and adjuvant chemotherapy ± radiotherapy may be an option. In advanced or recurrent HG-ESS, surgical cytoreduction and neoadjuvant or adjuvant chemotherapy can be considered. Alternative treatments, including biological agents and immunotherapy, are under investigation. LG-ESSs are indolent tumor with a 5-year overall survival (OS) of 80-100% and present as stage I-II at diagnosis in two third of patients. HG-ESSs carry a poor prognosis, with a median OS ranging from 11 to 24 months, and 70% of patients are in stage III-IV at presentation. UUS median OS ranges from 12 to 23 months and, at diagnosis, 70% of patients are in stage III-IV. The aim of this review is to assess the clinical, pathological, and biological features and the therapeutic options for malignant ESTs.

JAZF1, YWHAE and BCOR gene translocation in primary extrauterine low-grade and high-grade endometrial stromal sarcomas.

AIMS: JAZF1 translocation is the most common genetic change in low-grade (LG) endometrial stromal sarcoma (ESS), and YWHAE and BCOR translocations are common in high-grade (HG) ESS. Primary extrauterine ESS is rare, and there are limited data on molecular alterations in these tumours. METHODS AND RESULTS: Cases of primary extrauterine ESS, comprising eight LG-ESS cases and five HG-ESS cases were collected. Haematoxylin and eosin and immunohistochemical staining were used to observe the histomorphology and analyse related protein expression. JAZF1, YWHAE and BCOR rearrangements were explored with fluorescence in-situ hybridisation (FISH). In LG-ESS, the tumour cells resembled normal proliferative-phase endometrial stromal cells; CD10, oestrogen receptor and progesterone receptor were expressed in all eight cases. In HG-ESS, the tumour cells had uniform HG round and/or spindle morphology, sometimes with an LG component; CD10 was fully expressed in one case and focally expressed in four cases; BCOR was expressed in all five cases, and cyclin D1 in four of five cases. FISH analysis showed JAZF1 translocation in one of eight LG-ESS cases (12.5%). YWHAE translocation occurred in four of five HG-ESS cases, with a positivity rate of 80%. BCOR translocation was absent in all five cases. CONCLUSIONS: In extrauterine LG-ESS, the rate of JAZF1 rearrangement was significantly lower than in uterine LG-ESS. This result limited the value of JAZF1 translocation for diagnosis. YWHAE rearrangement is a common genetic change in extrauterine HG-ESS. Further studies are required to confirm these findings, especially in LG-ESS.

[Endometrial and other rare uterine sarcomas : Diagnostic aspects in the context of the 2020 WHO classification]. / Endometriale und weitere seltene uterine Sarkome : Diagnostische Aspekte im Kontext der WHO-Klassifikation 2020.

Uterine sarcomas are a heterogeneous group of rare malignancies. Mostly (40-50%), they are leiomyosarcomas, followed by endometrial stromal sarcomas (ESS), low-grade (LG) and high-grade (HG), as well as undifferentiated sarcoma of the uterus (UUS) and adenosarcomas (AS). Other, non-organ-specific tumours such as NTRK-rearranged spindle cell neoplasia, perivascular epithelioid cell tumour (PEComa) and inflammatory myofibroblastic tumour (IMT) are extremely difficult to differentiate.In the most recent WHO classification, endometrial stromal tumours are subdivided as follows: benign, expansively growing endometrial stromal nodule (ESN) with sharp demarcation, the histologically similar-looking LG-ESS with infiltrative growth, the highly malignant HG-ESS and, as a diagnosis of exclusion, the highly aggressive UUS lacking specific lines of differentiation. LG-ESS can be differentiated from HG-ESS in most cases histomorphologically and immunohistochemically, but molecular investigations are necessary in individual cases. HG-ESS can be divided into 4 subtypes (YWHAE/NUTM2 fusion low-grade component, YWHAE/NUTM2 fusion high-grade component, ZC3H7B-BCOR fusion or BCOR-ITD) on the basis of molecular findings. Prognostically unfavourable factors in AS are severe sarcomatous overgrowth, deep myometrial invasion, high-grade histology and lymphatic vessel invasion. Tumours with NTRK fusion are immunohistochemically positive for S100 and TRK. PEComas express cathepsin K and HMB45, as well as TFE3 when translocation is present. Almost every IMT shows an alteration in the ALK gene In the case of overlapping morphology and simultaneous therapeutic and prognostic relevance, it is becoming increasingly important to verify or confirm the suspected histomorphological diagnosis by immunohistochemical and possibly molecular investigations.

Practical roles for molecular diagnostic testing in ovarian adult granulosa cell tumour, Sertoli-Leydig cell tumour, microcystic stromal tumour and their mimics.

Within the last decade, molecular advances have provided insights into the genetics of several ovarian sex cord-stromal tumours that have otherwise been enigmatic. Chief among these advances are the identification of FOXL2, DICER1 and CTNNB1 mutations in adult granulosa cell tumours, Sertoli-Leydig cell tumours (SLCTs), and microcystic stromal tumours (MCSTs), respectively. As access to molecular diagnostic laboratories continues to become more widely available, the potential roles for tumour mutation testing in the pathological diagnosis of these tumours merit discussion. Furthermore, links to inherited cancer susceptibility syndromes may exist for some women with SLCT (DICER1 syndrome) and MCST [familial adenomatous polyposis (FAP)]. This review will address practical issues in deciding when and how to apply mutation testing in the diagnosis of these three sex cord-stromal tumours. The pathologist's role in recommending referral for formal risk assessment for DICER1 syndrome and FAP will also be discussed.

A Pan-Cancer Landscape Analysis Reveals a Subset of Endometrial Stromal and Pediatric Tumors Defined by Internal Tandem Duplications of BCOR.

BACKGROUND: The Polycomb Repressive Complex 1 (PRC1) regulates epigenetic silencing and is manifestly linked to rare cancer types. The X-linked BCOR gene (BCL-6 Corepressor) is a member of the PRC1 complex and potentiates transcriptional repression through BCL6 binding of PRC1. Accumulating evidence suggests that internal tandem duplications (ITD) of BCOR are oncogenic drivers in a subset of pediatric sarcomas and rare adult tumors. OBJECTIVE: We reviewed the genomic profiles of a large series of advanced cancer patients to determine the frequency and genomic spectrum of ITD of BCOR across cancer. METHODS: Tissues from 140,411 unique advanced cancers were sequenced by hybrid-capture-NGS-based comprehensive genomic profiling of 186-315 genes plus introns from 14 to 28 genes commonly rearranged in cancer, as well as RNA for 265 genes for a portion of these cases. RESULTS: BCOR-ITDs were present in 0.024% of all cases (33/140,411). Of this dataset, sarcoma cancer types were most frequent, 63.6% (21/33), either of uterine origin 52.4% (11/21), or pediatric (nonuterine) 42.8% (9/21). The identified BCOR-ITDs occurred most frequently in exon 15, near C-terminus, 69.7% (23/33), with a mean insertion length of 31.7 codons (range 30-38). Of uterine cases, an expert gynecologic pathology central review identified all these cases as having a similar high-grade morphology consistent with endometrial stromal sarcomas (ESS), and 90% of cases having a round cell component. Of the uterine sarcoma cases harboring exon 15 BCOR-ITDs, none simultaneously carried gene fusions typically associated with ESS. CONCLUSION: BCOR-ITDs define a rare subset of pediatric sarcomas and clinically aggressive endometrial stromal sarcoma cases, as defined by NGS for the first time. Our findings help delineate the pan-cancer landscape of this alteration and suggest the need for focused investigation to delineate the pro-oncogenic function of BCOR, along with any sensitivity to targeted therapies.

YWHAE-rearranged high-grade endometrial stromal sarcoma: Two-center case series and response to chemotherapy.

OBJECTIVES: YWHAE-rearranged high-grade endometrial stromal sarcoma (HG-ESS) is a rare, recently defined uterine sarcoma harboring t(10;17)(q22;p13) resulting in YWHAE-NUTM2A/B fusion. Chemotherapy sensitivity of metastatic YWHAE-rearranged HG-ESS is unknown. We reviewed the response to chemotherapy in women with YWHAE-rearranged HG-ESS to provide guidance for clinical management. METHODS: We retrospectively identified patients diagnosed with YWHAE-rearranged HG-ESS who received treatment for metastatic disease at our institutions. Cytogenetics or fluorescence in situ hybridization were performed in all cases to confirm rearrangement and, in conjunction with histopathology, a diagnosis of YWHAE-rearranged HG-ESS. Patient demographics, tumor histology, surgical procedures, radiation therapy, chemotherapy and treatment responses were collected. RESULTS: Seven patients were identified with YWHAE-rearranged HG-ESS and met criteria for inclusion in this study. The median age at diagnosis was 45 (range 42-47). All patients had undergone hysterectomy with bilateral salpingo-oophorectomy. FIGO stage at diagnosis was IVB in four patients and a single patient each at stage IIIB, II or I. Median follow-up for the cohort was 27months (range 6-123). Six patients received anthracycline-based chemotherapy, with two of six achieving a complete radiologic response. One patient received gemcitabine and docetaxel, resulting in a partial response. For three patients who died from metastatic disease, survival from initial diagnosis was 33, 100 and 123months. CONCLUSIONS: For metastatic YWHAE-rearranged HG-ESS, prolonged disease control following diagnosis was seen, with notable responses to anthracycline-based therapy. This emphasizes the need for appropriate molecular testing of uterine mesenchymal malignancies and suggests that chemotherapy is an effective treatment option for metastatic YWHAE-rearranged HG-ESS.

Silencing nc886, a Non-Coding RNA, Induces Apoptosis of Human Endometrial Cancer Cells-1A In Vitro.

BACKGROUND The role that nc886, a non-coding microRNA, plays in human endometrial cancer is unknown. The present study aimed to describe the functional role of nc886 in human endometrial cancer-1A (HEC-1A) cell line, which may provide another target for human endometrial cancer treatment. MATERIAL AND METHODS The expression levels of nv886 in normal human endometrial tissue and the early phase and late phase of human endometrial cancer tissues were determined and compared by fluorescence in situ hybridization (FISH). Small interference RNA (siRNA) was used to inhibit nc886, and cell proliferation was evaluated with the MTT test. mRNA levels of PKR, NF-κB, vascular endothelial growth factor (VEGF), and caspase-3 were determined against glyceraldehyde 3-phosphate dehydrogenase (GAPDH between the HEC-1A control group and the silenced group (nc886 silenced with siRNA) by real-time reverse transcription polymerase chain reaction (RT-PCR). The protein levels of PKR (total and phosphorylated form), NF-κB, VEGF, and caspase-3 were determined against GAPDH by Western blotting, and cell apoptosis was determined by flow cytometry. RESULTS Our results indicated that a higher level of nc886 was expressed in the late phase of human endometrial cancer tissue, less than in the early phase but still higher than in normal human endometrial tissue. After nc886 was silenced, protein levels of p-PKR (phosphorylated PKR) and caspase-3 were increased, whereas NF-κB and VEGF were decreased. CONCLUSIONS The rate of apoptosis in the silenced group was increased and the rate of cell proliferation was slower in comparison to the control.

[Values of JAZF1 gene rearrangement detected by fluorescence in-situ hybridization in diagnosis of endometrial stromal tumours].

Objective: To investigate the role of JAZF1 gene rearrangement in the diagnosis and differential diagnosis of endometrial stromal sarcomas by fluorescence in situ hybridization (FISH). Methods: JAZF1 gene rearrangement was analyzed by FISH in 129 cases of ESS diagnosed from January 2008 to December 2016 including 105 cases of low-grade endometrial stromal sarcoma (LG-ESS), 21 cases of high-grade endometrial stromal sarcoma (HG-ESS) and 3 cases of undifferentiated uterine sarcoma (UUS). Sixteen cases of the related tumours in uterus were also collected as control group. The results were compared with our previous studies of JAZF1/JJAZ1 fusion gene in ESS by RT-PCR. Results: Detection of JAZF1 gene rearrangement by FISH was successfully analyzed in 144 cases. JAZF1 gene alteration was detected in 63 cases, all of which were LG-ESS, with an overall positivity of 60.6% (63/104), while no JAZF1 gene rearrangement was found in all other cases. JAZF1 gene rearrangement was present in LG-ESS with classic histology (69.3%, 52/75), smooth muscle differentiation (2/10), sex cord-like differentiation (4/5), fibromyxoid change (1/5), clear cell change (0/1), skeletal muscle differentiation (0/1), and schwannoma-like palisading pattern (0/1). The different components in all the cases of LG-ESS with variant histology had the clonal origin, with or without JAZF1 gene alteration. Compared to the results of JAZF1/JJAZ1 fusion gene by RT-PCR, the positive rate of JAZF1 gene rearrangement in LG-ESS by FISH (61.9%, 26/42) was significantly higher than that of RT-PCR (30.0%, 12/40; P<0.01). Conclusions: JAZF1 gene rearrangement is present only in LG-ESS, but not in HG-ESS, UUS or other related tumours in uterus. The frequency of JAZF1 gene rearrangement varies between classic LG-ESS and different morphologic variants. It is frequently, but not consistently, present in classic LG-ESS and less often positive in variant cases. The results of JAZF1 gene alterations in LG-ESS with different morphologic variants support the contention that the endometrial stromal and their variant morphologic components have the same clonal origin. Detection of JAZF1 gene rearrangement by FISH is very useful for the diagnosis and differential diagnosis of ESS.

The application of next-generation sequencing-based molecular diagnostics in endometrial stromal sarcoma.

AIMS: Endometrial stromal sarcomas (ESSs) are divided into low-grade and high-grade subtypes, with the latter showing more aggressive clinical behaviour. Although histology and immunophenotype can aid in the diagnosis of these tumours, genetic studies can provide additional diagnostic insights, as low-grade ESSs frequently harbour fusions involving JAZF1/SUZ12 and/or JAZF1/PHF1, whereas high-grade ESSs are defined by YWHAE-NUTM2A/B fusions. The aim of this study was to evaluate the utility of a next-generation sequencing (NGS)-based assay in identifying ESS fusions in archival formalin-fixed paraffin-embedded tumour samples. METHODS AND RESULTS: We applied an NGS-based fusion transcript detection assay (Archer FusionPlex Sarcoma Panel) that targets YWHAE and JAZF1 fusions in a series of low-grade ESSs (n = 11) and high-grade ESSs (n = 5) that were previously confirmed to harbour genetic rearrangements by fluorescence in-situ hybridization (FISH) and/or reverse transcription polymerase chain reaction (RT-PCR) analyses. The fusion assay identified junctional fusion transcript sequences that corresponded to the known FISH/RT-PCR results in all cases. Four low-grade ESSs harboured JAZF1-PHF1 fusions with different junctional sequences, and all were correctly identified because of the open-ended nature of the assay design, using anchored multiplex polymerase chain reaction. Seven non-ESS sarcomas were also included as negative controls, and no strong ESS fusion candidates were identified in these cases. CONCLUSIONS: Our findings demonstrate good sensitivity and specificity of an NGS-based gene fusion assay in the detection of ESS fusion transcripts.

Genomic characterization of endometrial stromal sarcomas with array comparative genomic hybridization.

INTRODUCTION: The endometrial stromal sarcoma (ESS) is a very rare uterine sarcoma, counting for 1-3% of all gynecologic malignancies. ESS represents 0.2-8% of all uterine malignant tumors and accounts for about 10% of all uterine sarcomas. With regard to chromosomal aberrations, very little is known about benign and malignant endometrial stromal tumors. METHODS: 30 tumors, consisting of 4 cases of benign endometrial stromal nodule (ESN), 22 cases of low-grade ESS and 4 cases of undifferentiated endometrial sarcoma (UES), were analyzed by array-comparative genomic hybridization (aCGH). RESULTS: ESN did not show many copy number changes (CNCs) by aCGH. Frequent losses could be identified on chromosomes 7p and 19, and gains on chromosomes 1q, 6p and 8q. Low-grade ESS presented as a very heterogeneous group. 90% (20/22) of cases displayed aberrations. Most frequent changes were losses on chromosomes 7 and 22, and gains on chromosome 1q or 11. UES showed a high number of chromosomal aberrations and on every chromosome CNCs were detected. Most frequent changes were losses on chromosomes 1q, 2q (3/4, 75%) and 13, and gains on chromosomes 1q and 17p. CONCLUSION: Our data shows an increasing number of CNCs from ESN to low-grade ESS and to UES. However, the chromosomal aberrations differ considerably between the investigated ESN-, low-grade ESS- and UES cases and thus, a linear tumor progression seems to be unlikely.

Analysis of MDM2 Amplification in 43 Endometrial Stromal Tumors: A Potential Diagnostic Pitfall.

MDM2 amplification is known to occur in a variety of neoplasms and its detection by fluorescence in situ hybridization is helpful in distinguishing well-differentiated and dedifferentated liposarcoma from classic lipoma. We recently evaluated a mesenteric mass initially diagnosed as dedifferentiated liposarcoma, largely due to the neoplasm's myxoid morphology and MDM2 expression by immunohistochemistry, from a 46-yr-old woman with a history of uterine low-grade endometrial stromal sarcoma (LG-ESS) with a JAZF1 rearrangement. Our workup of the mesenteric mass revealed a JAZF1 rearrangement and a revised diagnosis of metastatic LG-ESS with myxoid change was rendered. Retrospective testing of the mesenteric mass was negative for MDM2 amplification, an uncommon, but known diagnostic pitfall in MDM2 expression by immunohistochemistry. As MDM2 amplification is not specific for the diagnosis of liposarcoma, we investigated its occurrence in 43 cases of endometrial stromal tumors: 14 uterine LG-ESS, 11 metastatic or recurrent uterine LG-ESS, 8 undifferentiated uterine sarcomas, 5 endometrial stromal nodules, and 4 high-grade ESS with YHWAE rearrangement. In addition, 40 of the 43 cases had previously undergone fluorescence in situ hybridization analysis of JAZF1, PHF1, and YHWAE. Two of the 43 cases (5%) had MDM2 amplification: one was a uterine LG-ESS (JAZF1 rearrangement) and the other was a undifferentiated uterine sarcoma (polysomy intact JAZF1, PHF1, and YHWAE), both metastatic to the lung. Both cases positive for MDM2 amplification showed MDM2 expression by immunohistochemistry. At last follow-up, both patients had died of disease (19 and 60 mo). Our study is the first to demonstrate MDM2 amplification in endometrial stromal tumor. Awareness of MDM2 amplification in endometrial stromal tumor is critical; particularly in locations more common to liposarcoma, to avoid diagnostic errors.

Endometrial stromal tumors: the new WHO classification.

Endometrial stromal tumors are rare uterine mesenchymal neoplasms that have intrigued pathologists for years, not only because they commonly pose diagnostic dilemmas, but also because the classification and pathogenesis of these tumors has been widely debated. The current World Health Organization recognizes 4 categories of endometrial stromal tumor: endometrial stromal nodule (ESN), low-grade endometrial stromal sarcoma (LG-ESS), high-grade endometrial stromal sarcoma (HG-ESS), and undifferentiated uterine sarcoma (UUS). uterine sarcoma. These categories are defined by the presence of distinct translocations as well as tumor morphology and prognosis. Specifically, the JAZF1-SUZ12 (formerly JAZF1-JJAZ1) fusion identifies a large proportion of ESN and LG-ESSs, whereas the YWHAE-FAM22 translocation identifies HG-ESSs. The latter tumors appear to have a prognosis intermediate between LG-ESS and UUS, which exhibits no specific translocation pattern. This review (1) presents the clinicopathologic features of endometrial stromal tumors; (2) discusses their immunophenotype; and (3) highlights the recent advances in molecular genetics which explain their pathogenesis and lend support for a new classification system.

Targeted RNA Sequencing Highlights a Diverse Genomic and Morphologic Landscape in Low-grade Endometrial Stromal Sarcoma, Including Novel Fusion Genes.

Low-grade endometrial stromal sarcoma (LGESS) represents a morphologically and genetically heterogenous mesenchymal neoplasm. Previous work has shown that approximately half of LGESS are characterized by JAZF1::SUZ12 gene fusions, while a smaller proportion involves rearrangement of other genes. However, a subset of cases has no known genetic abnormalities. To better characterize the genomic landscape of LGESS, we interrogated a cohort with targeted RNA sequencing (RNA-Seq). Cases previously diagnosed as low-grade endometrial stromal neoplasia (n=51) were identified and re-reviewed for morphology and subjected to RNA-Seq, of which 47 were successfully sequenced. The median patient age was 49 years (range: 19 to 85). The most commonly detected fusions were JAZF1::SUZ12 (n=26, 55%) and BRD8::PHF1 (n=3, 6%). In addition to the usual/typical LGESS morphology, some JAZF1::SUZ12 fusion tumors showed other morphologies, including fibrous, smooth muscle, sex-cord differentiation, and myxoid change. Novel translocations were identified in 2 cases: MEAF6::PTGR2 and HCFC1::PHF1 . Ten tumors (21%) had no identifiable fusion, despite a similar morphology and immunophenotype to fusion-positive cases. This suggests that a subset of cases may be attributable to fusion products among genes that are not covered by the assay, or perhaps altogether different molecular mechanisms. In all, these findings confirm that RNA-Seq is a potentially useful ancillary test in the diagnosis of endometrial stromal neoplasms and highlight their diverse morphology.

Recent developments in uterine mesenchymal neoplasms.

Smooth muscle and endometrial stromal tumours represent the two most common uterine mesenchymal neoplasms that may present diagnostic dilemmas for the practising surgical pathologist. Recent changes in morphological and staging criteria, as well as the discovery of new immunohistochemical markers, have improved the diagnosis and classification of these tumours. We highlight the difficulty in distinguishing tumour cell necrosis from infarct-type necrosis and the limited utility of p16 immunohistochemical expression in the diagnosis of leiomyosarcoma. We also discuss the controversial use of mitotic activity and necrosis as prognostic factors in endometrial stromal sarcomas. Emerging genetic information has also greatly expanded our understanding of 'sarcomagenesis' in both tumour types and may provide insight into potential therapeutic targets for the treatment of leiomyosarcoma and endometrial stromal sarcomas, harboring MED12 (mediator complex subunit 12) mutations and recurrent gene rearrangements, respectively. In this review, we discuss the core updates in the diagnosis and classification of uterine leiomyosarcomas and endometrial stromal sarcomas, highlighting new and important molecular genetic findings that may drive pathogenesis.

Gene expression signatures differentiate uterine endometrial stromal sarcoma from leiomyosarcoma.

OBJECTIVE: Endometrial stromal sarcoma (ESS) and leiomyosarcoma (LMS) are the two most common uterine sarcomas, but both are rare tumors. The aim of the present study was to compare the global gene expression patterns of ESS and LMS. METHODS: Gene expression profiles of 7 ESS and 13 LMS were analyzed using the HumanRef-8 BeadChip from Illumina. Differentially expressed candidate genes were validated using quantitative real-time PCR and immunohistochemistry. RESULTS: Unsupervised hierarchical clustering using all 54,675 genes in the array separated ESS from LMS samples. We identified 549 unique probes that were significantly differentially expressed in the two malignancies by greater than 2-fold with 1% FDR cutoff using one-way ANOVA with Benjamini-Hochberg correction, of which 336 and 213 were overexpressed in ESS and LMS, respectively. Genes overexpressed in ESS included SLC7A10, EFNB3, CCND2, ECEL1, ITM2A, NPW, PLAG1 and GCGR. Genes overexpressed in LMS included CDKN2A, FABP3, TAGLN, JPH2, GEM, NAV2 and RAB23. The top 100 genes overexpressed in LMS included those coding for myosin light chain and caldesmon, but not the genes coding for desmin or actin. CD10 was not overexpressed in ESS. Results for selected genes were validated by quantitative real-time PCR and immunohistochemistry. CONCLUSIONS: We present the first study in which gene expression profiling was shown to distinguish between ESS and LMS. The molecular signatures unique to each of these malignancies may aid in expanding the diagnostic battery for their differentiation, and may provide a molecular basis for prognostic studies and therapeutic target discovery.

Uterine Endometrial Stromal Tumors With Pure Low-Grade Morphology Harboring YWHAE::NUTM2 Fusions: Report of a Case Series Emphasizing Potential for High-Grade Transformation and Aggressive Behavior.

Uterine endometrial stromal sarcomas (ESS) with YWHAE::NUTM2 gene fusions are typically morphologically high-grade tumors composed of atypical round cells, sometimes associated with a low-grade fibromyxoid component; they are currently included in the category of high-grade ESS (HGESS). We report 5 morphologically pure low-grade endometrial stromal tumors harboring YWHAE::NUTM2 fusions, including 1 endometrial stromal nodule (ESN) and 4 low-grade endometrial stromal sarcomas (LGESS), an association only occasionally reported previously. Patients ranged from 30 to 51 (mean=43) years and tumors from 4.5 to 7.5 cm (mean=5.7). All were stage I at diagnosis (confined to the uterus). Microscopically, the 4 LGESS showed extensive "tongue-like" invasion of the myometrium, and the ESN was entirely confined to the endometrium with no myometrial invasion. All tumors were composed entirely of morphologically uniform bland ovoid cells resembling proliferative endometrial stroma. A fibromyxoid component was seen in 1 LGESS and the ESN; in the LGESS, this was the sole component. Atypical round cells characteristic of YWHAE::NUTM2 HGESS were not identified. Mitotic count ranged from <1 to 13 per 10 high-power fields (mean: 3). CD10 was positive in 2/4 (focal), estrogen receptor in 5/5 (focal=1; diffuse=4), progesterone receptor in 5/5 (focal=1; diffuse=4) and cyclin D1 was diffusely positive in 3/4. Follow-up was available in all 5 patients and ranged from 6 to 159 months (mean=72). Two patients with LGESS had recurrent disease at 15 and 155 months; 1 showed predominantly LGESS with rare round cells in the initial recurrence and pure HGESS in a subsequent recurrence, while the other patient's recurrent tumor was predominantly HGESS (90%) in a background of focal fibromyxoid LGESS (10%). Both patients rapidly progressed and died of disease within 5 months of high-grade recurrence. We show that rare cases of morphologically pure low-grade endometrial stromal tumors, some but not all with a fibromyxoid component, harbor YWHAE::NUTM2 fusions and may recur rapidly, with transformation to HGESS and aggressive behavior. Our findings suggest that at least a subset of YWHAE::NUTM2 HGESS evolves from LGESS. We suggest that cyclin D1 and CD10 staining should be performed in all LGESS. Diffuse staining for cyclin D1 and/or negative or focal staining for CD10 should suggest the possibility of a YWHAE::NUTM2 fusion, and appropriate molecular testing should be undertaken. Since no single morphological or immunohistochemical parameter is entirely sensitive for fusion status, we also suggest that testing for a YWHAE::NUTM2 gene fusion should be considered in all cases of LGESS and, if a fusion is present, this should raise the possibility of subsequent high-grade transformation and aggressive behavior, even though such cases should still be categorized as LGESS. Although seemingly rare, ESN and LGESS with YWHAE::NUTM2 fusions may be under-recognized due to a lack of routine fusion testing.

High-Grade Endometrial Stromal Sarcoma: Molecular Alterations and Potential Immunotherapeutic Strategies.

Endometrial stromal tumor (EST) is an uncommon and unusual mesenchymal tumor of the uterus characterized by multicolored histopathological, immunohistochemical, and molecular features. The morphology of ESTs is similar to normal endometrial stromal cells during the proliferative phase of the menstrual cycle. ESTs were first classified into benign and malignant based on the number of mitotic cells. However, recently WHO has divided ESTs into four categories: endometrial stromal nodules (ESN), undifferentiated uterine sarcoma (UUS), low-grade endometrial stromal sarcoma (LG-ESS), and high-grade endometrial stromal sarcoma (HG-ESS). HG-ESS is the most malignant of these categories, with poor clinical outcomes compared to other types. With advances in molecular biology, ESTs have been further classified with morphological identification. ESTs, including HG-ESS, is a relatively rare type of cancer, and the therapeutics are not being developed compared to other cancers. However, considering the tumor microenvironment of usual stromal cancers, the advance of immunotherapy shows auspicious outcomes reported in many different stromal tumors and non-identified uterine cancers. These studies show the high possibility of successful immunotherapy in HG-ESS patients in the future. In this review, we are discussing the background of ESTs and the BCOR and the development of HG-ESS by mutations of BCOR or other related genes. Among the gene mutations of HG-ESSs, BCOR shows the most common mutations in different ways. In current tumor therapies, immunotherapy is one of the most effective therapeutic approaches. In order to connect immunotherapy with HG-ESS, the understanding of tumor microenvironment (TME) is required. The TME of HG-ESS shows the mixture of tumor cells, vessels, immune cells and non-malignant stromal cells. Macrophages, neutrophils, dendritic cells and natural killer cells lose their expected functions, but rather show pro-tumoral functions by the matricellular proteins, extracellular matrix and other complicated environment in TME. In order to overcome the current therapeutic limitations of HG-ESS, immunotherapies should be considered in addition to the current surgical strategies. Checkpoint inhibitors, cytokine-based immunotherapies, immune cell therapies are good candidates to be considered as they show promising results in other stromal cancers and uterine cancers, while less studied because of the rarity of ESTs. Based on the advance of knowledge of immune therapies in HG-ESS, the new strategies can also be applied to the current therapies and also in other ESTs.

Recurrent KAT6B/A::KANSL1 Fusions Characterize a Potentially Aggressive Uterine Sarcoma Morphologically Overlapping With Low-grade Endometrial Stromal Sarcoma.

With the widespread application of next-generation sequencing, the genetic landscape of uterine mesenchymal neoplasms has been evolving rapidly to include several recently identified fusion genes. Although chromosomal rearrangements involving the 10q22 and 17q21.31 loci have been reported in occasional uterine leiomyomas decades ago, the corresponding KAT6B::KANSL1 fusion has been only recently identified in 2 uterine tumors diagnosed as leiomyoma and leiomyosarcoma. We herein describe 13 uterine stromal neoplasms carrying a KAT6B::KANSL1 (n=11) and KAT6A::KANSL1 (n=2) fusion. Patient ages ranged from 33 to 81 years (median, 49 y). Tumor size was 2.6 to 23.5 cm (median, 8.2 cm). Nine tumors were myometrium-centered, and 3 had an intracavitary component. Original diagnoses were mostly low-grade endometrial stromal sarcoma (LG-ESS; 10 cases) with atypical features (limited CD10 expression, sex cord-like features, pericytic vasculature, and frequent myxoid changes). Treatment was hysterectomy±bilateral salpingo-oophorectomy (10), myomectomy (1), and curettage (2). Five patients were disease-free at 6 to 34 months, 3 (27%) died of disease at 2 to 47 months, and 3 were alive with disease at 2, 17, and 17 years. Histologically, most tumors showed variable overlap with LG-ESS, but they were generally well-circumscribed lacking the extensive permeative and angioinvasive growth typical of LG-ESS. They were composed of monotonous medium-sized oval and spindle cells arranged into diffuse sheets with prominent spiral-type arterioles and frequent pericytoma-like vascular pattern. Variable myxoid stromal changes were frequent. Mitotic activity ranged from 1 to >20 in 10 HPFs. Immunohistochemistry showed variable expression of CD10 (12/13), estrogen receptor (8/11), progesterone receptor (8/11), smooth muscle actin (9/11), desmin (4/12), h-caldesmon (2/10), calretinin (3/8), inhibin (1/7), WT1 (4/7), cyclin D1 (5/11; diffuse in only 1 case), and pankeratin (5/10). This series characterizes a KAT6B/A::KANSL1 fusion-positive uterine stromal neoplasm within the morphologic spectrum of LG-ESS but with atypical features. The relationship of these neoplasms to genuine LG-ESS remains unclear. This molecular subtype of uterine endometrial stromal sarcoma has the potential for an unfavorable clinical course despite the absence of widely invasive growth; nevertheless, analysis of more cases is necessary to delineate the phenotypic spectrum and biological potential of this tumor.