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

A Novel CASC15-ALK and TFG-ROS1 Fusion Observed in Uterine Inflammatory Myofibroblastic Tumor

The majority of inflammatory myofibroblastic tumors (IMTs) in the gynecologic tract occur in the uterine corpus and harbor anaplastic lymphoma kinase ( ALK ) rearrangement. Herein, we report 1 uterine IMT case with a novel fusion involving ALK and 1 uterine IMT case with ROS1 rearrangement. The ages of the patients were 56 and 57 yr, respectively. The tumor size was 10.0 and 8.0 cm, respectively. Both patients had stage IB disease. Histologically, the 2 IMT cases had classic morphologic features and predominantly comprised bland spindle cells with hypercellular (fascicular/storiform) and hypocellular (myxoid rich) areas admixed with variably prominent lymphoplasmacytic infiltration. Immunohistochemically, the ALK -rearranged case was positive for ALK , and the ROS1 -rearranged case was positive for ROS1 . Both cases were diffusely positive for desmin. The tumor cells were variably positive for estrogen receptor (1/2 cases, 50.0%) and progesterone receptor (1/2 cases, 50.0%). Targeted RNA sequencing revealed one case each with either a novel CASC15-ALK or TFG-ROS 1 fusion. We identified a novel ALK fusion partner CASC15 in IMT and described the first uterine IMT with a TFG-ROS1 fusion. This study improves our understanding of molecular events in IMT.

Expanding the molecular spectrum of gene fusions in endometrial stromal sarcoma: Novel subunits of the chromatin remodeling complexes PRC2 and NuA4/TIP60 as alternative fusion partners

Endometrial stromal sarcomas (ESS) are morphologically and molecularly heterogeneous. We report novel gene fusions (EPC1::EED, EPC1::EZH2, ING3::PHF1) identified by targeted RNA sequencing in five cases. The ING3::PHF1-fusion positive ESS presented in a 58-year-old female as extrauterine mesocolonic, ovarian masses, and displayed large, monomorphic ovoid-to-epithelioid cells arranged in solid sheets. The patient remained alive with disease 13 months after surgery. The three ESS with EPC1::EED occurred in the uterine corpus in patients with a median age of 58 years (range 27-62 years). One tumor showed a uniform epithelioid nested morphology, while the other two were composed of monomorphic spindle cells in fascicles with elevated mitotic figures, focal tumor cell necrosis, and lymphovascular invasion. At a median follow-up of 20 months, two patients developed local recurrence, including one with concomitant distant metastasis, while one patient remained free of disease. All three patients were alive at the last follow-up. The EPC1::EZH2-fusion positive ESS presented in a 52-year-old female in the uterus, and displayed uniform spindled cells arranged in short fascicles, with focally elevated mitotic activity but without necrosis. The patient remained free of disease 3 months after surgery. All cases were diffusely positive for CD10; four diffusely express estrogen and progesterone receptors. Our study expands the molecular spectrum of EPC1 and PHF1-related gene fusions in ESS to include additional novel subunits of the PRC2 and/or NuA4/TIP60 complexes. These cases displayed a monomorphic epithelioid or spindled phenotype, spanning low-grade and high-grade cytomorphology, all expressing CD10 and commonly ER and PR, and are prone to local and/or distant spread.

Data Set for Reporting of Uterine Malignant and Potentially Malignant Mesenchymal Tumors: Recommendations From the International Collaboration on Cancer Reporting (ICCR)

The International Collaboration on Cancer Reporting (ICCR) seeks to produce standardized, evidence-based protocols for the reporting of tumors with the aim of ensuring that all cancer reports generated worldwide will be of similar high quality and record the same elements. Herein, we describe the development of the data set for the reporting of uterine malignant and potentially malignant mesenchymal tumors by a panel of expert pathologists and a single clinician and provide the commentary and rationale for the inclusion of core and noncore elements. This data set, which incorporates the recent updates from the 5th edition of the World Health Organization Classification of Female Genital Tumors, addresses several subjects of debate including which mesenchymal tumors should be graded, how to document extent of invasion, mitotic counts, and the role of ancillary testing in tumor diagnosis and patient management. The inclusion of elements is evidence-based or based on consensus of the expert panel with clinical relevance being the guiding standard.

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.

Metastatic low-grade endometrial stromal sarcoma with variable morphologies in the ovaries and mesentery: A case report

BACKGROUND

Low-grade endometrial stromal sarcoma (LGESS) classically exhibits a proliferative morphology. However, morphological variation of extrauterine tumors presents a diagnostic challenge.

CASE SUMMARY

We report the case of a 76-year-old female patient with extensive extrauterine and abdominal neoplastic lesions. Computed tomography showed massive pleural and ascitic fluid, and there was an increase in serum cancer antigen 125. She underwent bilateral adnexectomy and tumor resection. The right ovary had been replaced by a multinodular mass that was 8.5 cm × 4.5 cm × 3.5 cm in size. In addition, there was a 24 cm × 15 cm × 13 cm mesenteric mass, which was also multinodular, with local invasion of the intestinal serosa and underlying muscle. Under the microscope, the tumors in different places exhibited two different patterns, thus presenting great challenges to diagnosis and treatment. Thorough pathological assessment eliminated all differential diagnoses in favor of metastatic LGESS derived from a 20-year-old primary tumor initially misdiagnosed as leiomyosarcoma.

CONCLUSION

LGESS morphology varies according to tumor location. Accurate diagnosis is critical for appropriate treatment and improved prognosis and patient care.

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.

Low-grade endometrial stromal sarcoma-like tumors in male with JAZF1 gene fusions

Low-grade endometrial stromal sarcoma (ESS) is a hormone-responsive low-grade sarcoma typically occurring in the uterine corpus in women. Their genetic hallmarks are recurrent gene fusions involving JAZF1, partnering with either SUZ12 gene or less commonly with PHF1. Low-grade ESS-like sarcoma, or endometrioid stromal sarcoma, is exceptionally rare in males and has been reported to date only in two cases, one in the paratesticular area and the other of prostatic stromal origin. We report herein two new cases of low-grade ESS-like sarcoma in male patients, one presenting as a periprostatic/peri-rectal mass with a JAZF1-GLI3 fusion, while the other as a paratesticular mass with a JAZF1-PHF1 fusion. As the GLI3 fusion appeared novel, we searched the transcriptional signature of 35 low-grade ESS from our archives and found a similar JAZF1-GLI3 fusion in a low-grade ESS arising from the uterine corpus, supporting a common pathogenesis. Histopathologically, both cases demonstrate cellular, monotonous proliferation of ovoid to fusiform cells with a background of arteriolar vascular network. Immunohistochemically, the neoplastic cells express ER, PR, and CD10, similar to ESS. One case also expresses diffuse and strong AR. On follow-up, the patient with the periprostatic mass recurred 2 years after initial surgery with peritoneal "sarcomatosis." We describe the salient diagnostic morphologic, immunohistochemical, and molecular features and discuss the differential diagnosis and possible pathogenesis of this unusual entity.

TSC2-mutant uterine sarcomas with JAZF1-SUZ12 fusions demonstrate hybrid features of endometrial stromal sarcoma and PEComa and are responsive to mTOR inhibition

Uterine perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal neoplasm that occasionally shares morphologic and immunohistochemical overlap with low- and high-grade endometrial stromal sarcoma (LGESS and HGESS). In this study, we sought to characterize the clinical, morphologic, genetic, and epigenetic features of five uterine sarcomas that display histologic features of LGESS, HGESS, and PEComa. All tumors demonstrated epithelioid cells often associated with a low-grade spindled component resembling LGESS, with both regions expressing CD10, ER, PR, variable HMB45, and Melan-A immunoreactivity, and strong cathepsin K and pS6 expression. Targeted massively parallel sequencing analysis revealed the presence of somatic TSC2 mutations in all five cases, of which four harbored concurrent or consecutive JAZF1-SUZ12 gene fusions. Unsupervised hierarchical clustering analysis of methylation profiles of TSC2-mutant uterine sarcomas (n = 4), LGESS (n = 10), and HGESS (n = 12) demonstrated two clusters consisting of (1) all LGESS and TSC2-mutant uterine sarcomas and (2) all HGESS. KEGG pathway analysis detected methylation differences in genes involved in PI3K/AKT, calcium, and Rap1 signaling. TSC2-mutant uterine sarcomas were responsive to hormone suppression, and mTOR inhibition demonstrated clinical benefit in four patients with these neoplasms. Our results suggest that these tumors represent histologically distinctive LGESS with TSC2 mutations. TSC2 mutations and JAZF1-SUZ12 fusion may help diagnose these tumors and possibly direct effective treatment.

Isolated ureteral extrauterine endometrial stromal sarcoma: an unusual presentation

Extrauterine endometrial stromal sarcomas (EUESSs) are rare tumours occurring without primary uterine involvement. They are classified as primary or secondary, depending on uterine involvement by stromal sarcomas. A 56-year-old woman who earlier underwent bilateral modified radical mastectomy for adenocarcinoma and total abdominal hysterectomy for endometrial stromal sarcoma, followed by tamoxifen therapy, presented with left loin pain. On evaluation, she had a left renal calculus with hydroureteronephrosis. Before percutaneous nephrolithotripsy, ureteroscopy revealed a polypoidal mass that was diagnosed as EUESS. The mass arose primarily within the ureteral lumen, with periureteric tissue uninvolved. She underwent left radical nephroureterectomy with adjuvant hormonal treatment. This is probably the first case of EUESS arising de novo from within the ureteral lumen without endometriosis, to be reported in medical literature. Immunohistochemistry facilitates earlier diagnosis. Cytoreductive surgery is the definitive treatment and multidisciplinary approach helps in overall survival of the patient.

Re-evaluating tumors of purported specialized prostatic stromal origin reveals molecular heterogeneity, including non-recurring gene fusions characteristic of uterine and soft tissue sarcoma subtypes

Tumors of purported specialized prostatic stromal origin comprise prostatic stromal sarcomas (PSS) and stromal tumors of uncertain malignant potential (STUMP). Prior studies have described their clinicopathologic characteristics, but the molecular features remain incompletely understood. Moreover, these neoplasms are morphologically heterogeneous and the lack of specific adjunctive markers of prostatic stromal lineage make precise definition more difficult, leading some to question whether they represent a specific tumor type. In this study, we used next-generation DNA and RNA sequencing to profile 25 primary prostatic mesenchymal neoplasms of possible specialized prostatic stromal origin, including cases originally diagnosed as PSS (11) and STUMP (14). Morphologically, the series comprised 20 cases with solid architecture (11 PSS and 9 STUMP) and 5 cases with phyllodes-like growth pattern (all STUMP). Combined DNA and RNA sequencing results demonstrated that 19/22 (86%) cases that underwent successful sequencing (either DNA or RNA) harbored pathogenic somatic variants. Except for TP53 alterations (6 cases), ATRX mutations (2 cases), and a few copy number variants (-13q, -14q, -16q and +8/8p), the findings were largely nonrecurrent. Eight gene rearrangements were found, and 4 (NAB2-STAT6, JAZF1-SUZ12, TPM3-NTRK1 and BCOR-MAML3) were useful for reclassification of the cases as specific entities. The present study shows that mesenchymal neoplasms of the prostate are morphologically and molecularly heterogeneous and include neoplasms that harbor genetic aberrations seen in specific mesenchymal tumors arising in other anatomic sites, including soft tissue and the uterus. These data suggest that tumors of purported specialized prostatic stromal origin may perhaps not represent a single diagnostic entity or specific disease group and that alternative diagnoses should be carefully considered.

NCCN Guidelines® Insights: Uterine Neoplasms, Version 3.2021

The NCCN Guidelines for Uterine Neoplasms provide recommendations for diagnostic workup, clinical staging, and treatment options for patients with endometrial cancer or uterine sarcoma. These NCCN Guidelines Insights focus on the recent addition of molecular profiling information to aid in accurate diagnosis, classification, and treatment of uterine sarcomas.

Molecular pathogenesis and prognostication of "low-grade'' and "high-grade" endometrial stromal sarcoma

Endometrial stromal sarcomas (ESS) are a heterogeneous group of rare mesenchymal cancers. Considerable knowledge has been gained in recent years about the molecular characteristics of these cancers, which helps to classify them in a more meaningful manner leading to improved diagnosis, prognostication, and treatment. According to this classification, ESS is now grouped as low‐ or high‐grade. ESS may have overlapping clinical presentation, morphology, and immunohistochemical profile. Their genetic characteristics allow subdivision of many of them depending on which pathogenetically important fusion genes they carry, but clearly much more needs to be unraveled in this regard. We here provide an overview of the molecular pathogenetic knowledge gained so far on low‐ and high‐grade ESS.

Italian consensus conference on management of uterine sarcomas on behalf of S.I.G.O. (Societa' italiana di Ginecologia E Ostetricia)

BACKGROUND

Uterine sarcomas are very rare tumours with different histotypes, molecular features and clinical outcomes; therefore, it is difficult to carry out prospective clinical trials, and this often results in heterogeneous management of patients in the clinical practice.

AIM

We planned to set up an Italian consensus conference on these diseases in order to provide recommendations on treatments and quality of care in our country.

RESULTS

Early-stage uterine sarcomas are managed by hysterectomy + bilateral salpingo-oophorectomy according to menopausal status and histology; lymphadenectomy is not indicated in patients without bulky nodes, and morcellation must be avoided. The postoperative management is represented by observation, even though chemotherapy can be considered in some high-risk patients. In early-stage low-grade endometrial stromal sarcoma and adenosarcomas without sarcomatous overgrowth, hormonal adjuvant treatment can be offered based on hormone receptor expression. In selected cases, external beam radiotherapy ± brachytherapy can be considered to increase local control only. Patients with advanced disease involving the abdomen can be offered primary chemotherapy (or hormonal therapy in the case of low-grade endometrial stromal sarcoma and adenosarcoma without sarcomatous overgrowth), even if potentially resectable in the absence of residual disease in order to test the chemosensitivity (or hormonosensitivity); debulking surgery can be considered in patients with clinical and radiological response. Chemotherapy is based on anthracyclines ± ifosfamide or dacarbazine. Palliative radiotherapy can be offered for symptom control, and stereotactic radiotherapy can be used for up to five isolated metastatic lesions.

CONCLUSIONS

Treatment of uterine sarcoma should be centralised at referral centres and managed in a multidisciplinary setting.

Gynecological Sarcomas: Molecular Characteristics, Behavior, and Histology-Driven Therapy

Gynecological sarcomas represent 3% to 4% of all gynecological malignancies and 13% of all sarcomas. The uterus is the most frequent primary site (83%); less frequently sarcomas are diagnosed originating from the ovary (8%), vulva and vagina (5%), and other gynecologic organs (2%). As the classification of gynecologic sarcomas continues to diversify, so does the management. Accurate histopathologic diagnosis, utilizing appropriate ancillary immunohistochemical and molecular analysis, could lead to a more personalized approach. However, there are subtypes that require further definition, with regard to putative predictive markers and optimal management. The aim of this review is to highlight the importance of accurate diagnosis and classification of gynecologic sarcoma subtypes by the surgical pathologist in order to provide more tailored systemic treatment, and to highlight the increasing importance of close collaboration between the pathologist and the oncologist.

Detection of MEAF6-PHF1 translocation in an endometrial stromal nodule

Endometrial stromal nodule (ESN) and low-grade endometrial stromal sarcoma (LG-ESS) are rare uterine tumors known as endometrial stromal tumors (ESTs). In addition to their similarity in morphological features, recent studies have shown that these two tumors share common genetic alterations. In particular, JAZF1-SUZ12 fusion is found with high frequency in both ESN and LG-ESS. In LG-ESS, some minor fusions have also been described, which include rearrangements involving PHF1 and its partner genes, such as JAZF1, EPC1, MEAF6, BRD8, EPC2, and MBTD1. Because of the rarity of ESN, genetic alterations other than JAZF1 fusion have not been investigated in detail. In this study, we performed a next-generation sequencing-based analysis in a case of ESN with peripheral metaplastic bone formation and detected MEAF6-PHF1 fusion, which has been reported in a small subset of uterine LG-ESSs and soft tissue ossifying fibromyxoid tumors. The finding that MEAF6-PHF1 fusion is a background genetic abnormality detected both in ESN and LG-ESS, along with JAZF1-SUZ12, provides further support for the similarity and continuum between these two types of ESTs. Furthermore, the association between metaplastic bone formation and MEAF6-PHF1 fusion may not be limited to soft tissue tumors.

Uterine Mesenchymal Tumors: Update on Classification, Staging, and Molecular Features

The spectrum of mesenchymal neoplasia in the uterus has expanded in recent years. First, the identification of prevalent, recurrent molecular alterations has led to a more biologically and clinically congruent classification of endometrial stromal tumors. Likewise, the diagnostic criteria of several rare and miscellaneous tumor types have been refined in recent case series (Perivascular Epithelioid Cell tumor, inflammatory myofibroblastic tumor). Pure mesenchymal tumors are still broadly classified based on morphology according to the tumor cell phenotype. Smooth muscle tumors predominate in frequency, followed by tumors of endometrial stromal derivation; the latter are covered in depth in this article with an emphasis on defining molecular alterations and their morphologic and clinical correlates. The remaining entities comprise a miscellaneous group in which cell derivation does not have a normal counterpart in the uterus (eg, rhabdomyosarcoma) or is obscure (eg, undifferentiated uterine sarcoma). This article discusses their clinical relevance, recent insights into their molecular biology, and the most important differential diagnoses. Regarding the latter, immunohistochemistry and (increasingly) molecular diagnostics play a role in the diagnostic workup. We conclude with a few considerations on intraoperative consultation and macroscopic examination, as well as pathologic staging and grading of uterine sarcomas as per the most recent American Joint Cancer Commission and the Fédération Internationale de Gynécologie et d'Obstétrique staging systems.

A cell-based splicing reporter system to identify regulators of cis-splicing between adjacent genes

Chimeric RNAs generated by cis-splicing between adjacent genes (cis-SAGe) are increasingly recognized as a widespread phenomenon. These chimeric messenger RNAs are present in normal human cells, and are also detected in various cancers. The mechanisms for how this group of chimeras is formed are not yet clear, in part due to the lack of a tractable system for their experimental investigation. Here we developed a fast, easy and versatile cell-based reporter system to identify regulators of cis-SAGe. The reporter, consisting of four main cassettes, simultaneously measures the effects of a candidate regulator on cis-SAGe and canonical splicing. Using this cell-based assay, we screened 102 candidate factors involved in RNA pol II cleavage and termination, elongation, splicing, alternative splicing and R-loop formation. We discovered that two factors, SRRM1 and SF3B1, affect not only cis-SAGe chimeras, but also other types of chimeric RNAs in a genome-wide fashion. This system can be used for studying trans-acting factors and cis-acting sequence elements and factors, as well as for screening small molecule inhibitors.

Metastatic low-grade endometrial stromal sarcoma of uterus presenting as a primary pancreatic tumor: case presentation and literature review

BACKGROUND

Metastatic tumors to the pancreas are uncommon, accounting for approximately 2% of pancreatic malignancies. The most common primary tumors to give rise to pancreatic metastases are carcinomas.

CASE PRESENTATION

A 50-year old female patient was investigated for a cause of abdominal discomfort. She had a 2-year history of menorrhagia and dysmenorrhea which was ascribed to a fibroid uterus. On imaging, she was found to have a large solid and cystic mass in the tail of the pancreas. Imaging also confirmed a fibroid uterus. A distal pancreatectomy and splenectomy showed a 9 cm circumscribed mass within, and grossly confined to, the parenchyma of the pancreatic tail. Microscopically, the pancreatic lesion was lobulated, and well-circumscribed, but focally infiltrative. It comprised sheets of uniform spindled to epithelioid cells with round to oval nuclei, coarse to vesicular chromatin, visible nucleoli, nuclear grooves and clear to eosinophilic cytoplasm. Prominent arterioles were identified. The stroma was collagenized in areas. Occasional hemosiderin-laden macrophages were seen, and focal cystic change was present. There was no evidence of nuclear pleomorphism, mitotic activity or necrosis, and there was no evidence of endometriosis despite multiple sections being taken. Immunohistochemistry showed that the tumor cells were positive for CD10, estrogen receptor (ER), progesterone receptor (PR), Wilms tumor-1 (WT-1) and smooth muscle actin (SMA). RNA sequencing detected a PHF1 rearrangement. The morphological, immunohistochemical and molecular features were of a low-grade endometrial stromal sarcoma (LG-ESS). Subsequent total hysterectomy and bilateral salpingo-oophorectomy 3 months later, showed uterine fibroids and a 5 cm low-grade endometrial stromal sarcoma confined to the uterus, with lymphatic invasion.

CONCLUSIONS

To the best of our knowledge, this is the first documented case of metastatic endometrial stromal sarcoma of uterus presenting as a primary pancreatic neoplasm. An unexpected extra-uterine location and unusual presentation of ESS may make the diagnosis challenging, despite classic histological features. Morphological, immunohistochemical and molecular findings must be combined to render the correct diagnosis.

Low-grade Endometrioid Stromal Sarcoma of the Paratestis: A Novel Report With Molecular Confirmation of JAZF1/SUZ12 Translocation

Tumors with Müllerian-like serous or mucinous phenotypes originating in the testis and its adnexa are rare neoplasms that have been increasingly recognized in recent years. Cystadenomas with or without ovarian-type stroma, borderline tumors, and adenocarcinomas are the main documented types. Although a handful cases of putative endometrioid adenocarcinomas have been reported, to our knowledge no case of endometrial stromal-type neoplasm has ever been reported in the literature. A 59-year-old man presented with a 2 cm left intrascrotal mass that was found on sonographic examination to arise from the epididymal tail with prominent vascularization. He was otherwise healthy without significant clinical history, endocrinopathy, or external hormone therapy. His testicular tumor markers (beta-HCG, AFP) were normal. Histologic examination of the resection showed a multinodular tumor closely associated with the epididymis and composed of monotonous rounded to ovoid cells with scanty cytoplasm and prominent spiral-like arterioles and capillaries. Mitotic activity was high. No other tumor component was seen. Immunohistochemistry revealed strong and diffuse expression of vimentin, CD10, estrogen receptor, and progesterone receptor. Molecular examination (performed on paraffin-embedded tumor tissue using a 517 gene fusion next-generation sequencing assay) showed a JAZF1/SUZ12 translocation, which was then confirmed by fluorescence in situ hybridization (FISH). These findings are consistent with a low-grade endometrioid stromal sarcoma originating in the paratestis. This report represents a novel addition to the growing spectrum of Müllerian-analog testicular adnexal neoplasms.

Treatment of low-grade endometrial stromal sarcoma in a nulligravid woman

A 32 year-old nulligravid woman with a uterine mass underwent exploratory laparotomy with myomectomy. Final pathology revealed a low-grade endometrial stromal sarcoma (ESS) with positive margins. She subsequently underwent definitive robotic hysterectomy and bilateral salpingectomy with ovarian preservation. She was diagnosed with a stage IB low-grade ESS. She is currently undergoing observation. Discussion of classification, surgical options, and adjuvant therapy is presented.

Unusual Presentations of Gynecologic Tumors: Primary, Extrauterine, Low-Grade Endometrioid Stromal Sarcoma

Context.—

Low-grade endometrial stromal sarcomas, when uterine in location, are relatively easy to diagnose because of characteristic morphology and patterns of myometrial invasion. However, when they occur at extrauterine sites, they fall under the broad umbrella of small round blue cell tumors, making diagnosis challenging, especially when they have variant morphologic features and lack the characteristic pattern of invasion.

Objectives.—

To provide an insight into the sites of occurrence of low-grade endometrioid stromal sarcomas, the variant morphologic patterns, clues to diagnosis, and the usefulness of immunohistochemistry as an aid to facilitate correct diagnosis. The outcome of these tumors, in comparison with their uterine counterpart, is also discussed.

Data Sources.—

Existing peer-reviewed literature was reviewed.

Conclusions.—

Low-grade endometrioid stromal sarcoma is an uncommon neoplasm that can be misdiagnosed because of its rarity, unusual location, and presence of numerous variant histologic patterns that mimic other tumors. Knowledge of those features; consideration of this tumor in the differential diagnosis of small, round blue cell tumors at any location in a woman; and an appropriate use of immunohistochemistry can help facilitate the diagnosis.

Systemic treatment in adult uterine sarcomas

Uterine sarcomas (US) are rare mesenchymal tumours of the uterus and are divided mainly into uterine leiomyosarcoma (uLMS), low grade endometrial stromal sarcoma (LG-ESS), high grade endometrial stromal sarcoma (HG-ESS), adenosarcomas and high grade undifferentiated sarcoma (HGUS). US are often high-grade tumours with a high local recurrence rate and metastatic risk. We here discuss the current standard of care and knowledge of systemic therapy for adult uterine sarcomas, in particular uLMS, LG-ESS, HG-ESS and HGUS, in both the adjuvant as well as the metastatic setting.

Myxoid Mesenchymal Tumors of the Uterus: An Update on Classification, Definitions, and Differential Diagnosis

Tumors with a predominant myxoid stroma are rare in the uterus. When encountered, however, they pose a diagnostic challenge. Traditionally myxoid leiomyosarcoma has been the most important consideration in this category, given its adverse prognosis and deceptively bland morphology. Conventional features of malignancy are variably present; in contrast, an infiltrative tumor border is a consistent pathologic characteristic. More recently, previously under-recognized lesions have been identified, in part due to our growing knowledge of their underlying molecular alterations: uterine inflammatory myofibroblastic tumor frequently harbors ALK rearrangements and a novel ZC3H7B-BCOR gene fusion has been described in a subset of myxoid high-grade endometrial stromal sarcomas. These tumors need to be distinguished from myxoid leiomyosarcoma, as by comparison have a less aggressive course and are amenable to targeted treatments. In addition, uterine mesenchymal tumors with malignant potential need to be distinguished from benign tumors and epithelial and mixed malignancies. This review aims to discuss our current understanding of the most common uterine myxoid neoplasms: their clinical features, their distinguishing histopathologic, immunohistochemical, and molecular features and the clues and pitfalls in their diagnosis.

Identification and Characterization of Renal Cell Carcinoma Gene Markers

Microarray gene expression profiling has been used to distinguish histological subtypes of renal cell carcinoma (RCC), and consequently to identify specific tumor markers. The analytical procedures currently in use find sets of genes whose average differential expression across the two categories differ significantly. In general each of the markers thus identified does not distinguish tumor from normal with 100% accuracy, although the group as a whole might be able to do so. For the purpose of developing a widely used economically viable diagnostic signature, however, large groups of genes are not likely to be useful. Here we use two different methods, one a support vector machine variant, and the other an exhaustive search, to reanalyze data previously generated in our Lab (Lenburg et al. 2003). We identify 158 genes, each having an expression level that is higher (lower) in every tumor sample than in any normal sample, and each having a minimum differential expression across the two categories at a significance of 0.01. The set is highly enriched in cancer related genes (p = 1.6 × 10–12), containing 43 genes previously associated with either RCC or other types of cancer. Many of the biomarkers appear to be associated with the central alterations known to be required for cancer transformation. These include the oncogenes JAZF1, AXL, ABL2; tumor suppressors RASD1, PTPRO, TFAP2A, CDKN1C; and genes involved in proteolysis or cell-adhesion such as WASF2, and PAPPA.

Molecular Pathology: Predictive, Prognostic, and Diagnostic Markers in Uterine Tumors

This article focuses on the diagnostic, prognostic, and predictive molecular biomarkers in uterine malignancies, in the context of morphologic diagnoses. The histologic classification of endometrial carcinomas is reviewed first, followed by the description and molecular classification of endometrial epithelial malignancies in the context of histologic classification. Taken together, the molecular and histologic classifications help clinicians to approach troublesome areas encountered in clinical practice and evaluate the utility of molecular alterations in the diagnosis and subclassification of endometrial carcinomas. Putative prognostic markers are reviewed. The use of molecular alterations and surrogate immunohistochemistry as prognostic and predictive markers is also discussed.

Novel High-grade Endometrial Stromal Sarcoma: A Morphologic Mimicker of Myxoid Leiomyosarcoma

Endometrial stromal sarcomas (ESS) are often underpinned by recurrent chromosomal translocations resulting in the fusion of genes involved in epigenetic regulation. To date, only YWHAE-NUTM2 rearrangements are associated with distinctive high-grade morphology and aggressive clinical behavior. We identified 3 ESS morphologically mimicking myxoid leiomyosarcoma of the uterus and sought to describe their unique histopathologic features and identify genetic alterations using next-generation sequencing. All cases displayed predominantly spindled cells associated with abundant myxoid stroma and brisk mitotic activity. Tumors involved the endometrium and demonstrated tongue-like myometrial infiltration. All 3 were associated with an aggressive clinical course, including multisite bony metastases in 1 patient, progressive peritoneal disease after chemotherapy in another, and metastases to the lung and skin in the last patient. All 3 ESS were found to harbor ZC3H7B-BCOR gene fusions by targeted sequencing and fluorescence in situ hybridization. On the basis of the review of these cases, we find that ESS with ZC3H7B-BCOR fusion constitutes a novel type of high-grade ESS and shares significant morphologic overlap with myxoid leiomyosarcoma.

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 landscape of endometrial stromal sarcoma of uterus

Although recurrent gene fusions such as JAZF1-JJAZ1 are considered driver events for endometrial stromal sarcoma (ESS) development, other genomic alterations remain largely unknown. In this study, we performed whole-exome sequencing, transcriptome sequencing and copy number profiling for five ESSs (three low-grade ESS (LG-ESS) and two undifferentiated uterine sarcomas (UUSs)). All three LG-ESSs exhibited either one of JAZF1-SUZ12, JAZF1-PHF1 and MEAF6-PHF1 fusions, whereas the two UUSs did not. All ESSs except one LG-ESS exhibited copy number alterations (CNAs), many of which encompassed cancer-related genes. In UUSs, five CNAs encompassing cancer-related genes (EZR, CDH1, RB1, TP53 and PRKAR1A) accompanied their expressional changes, suggesting that they might stimulate UUS development. We found 81 non-silent mutations (35 from LG-ESSs and 46 from UUSs) that included 15 putative cancer genes catalogued in cancer-related databases, including PPARG and IRF4 mutations. However, they were non-recurrent and did not include any well-known mutations, indicating that point mutations may not be a major driver for ESS development. Our data show that gene fusions and CNAs are the principal drivers for LG-ESS and USS, respectively, but both may require additional genomic alterations including point mutations. These differences may explain the different biologic behaviors between LG-ESS and UUS. Our findings suggest that ESS development requires point mutations and CNAs as well as the gene fusions.

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.

Molecular Cytogenetic Analysis of JAZF1, PHF1, and YWHAE in Endometrial Stromal Tumors: Discovery of Genetic Complexity by Fluorescence in Situ Hybridization

Diagnosis of endometrial stromal tumors (ESTs) can be challenging, particularly endometrial stromal sarcomas (ESSs) because of variable histologic appearance, long latency to recurrence, frequent metastases with unknown primary, and overlap with endometrial stromal nodules and undifferentiated uterine sarcomas. To enhance EST diagnosis, a break-apart strategy fluorescence in situ hybridization panel to detect JAZF1, PHF1, and YWHAE rearrangements was applied to a cohort of primary or metastatic endometrial stromal nodules, ESSs, or undifferentiated uterine sarcomas (36 cases for JAZF1, 24 of which were also assessed for PHF1 and YWHAE), 24 myometrium/endometrium controls, and 37 non-ESTs in the differential diagnosis. JAZF1 was the most frequently altered gene and occurred in all EST types, JAZF1 and/or PHF1 were mutually exclusive from YWHAE involvement, and uterine and extrauterine ESTs have a shared pathogenesis. We further defined frequency of these rearrangements and provided a resource demonstrating the signal complexity that can manifest when evaluating JAZF1. Rearrangement of JAZF1 occurred in 47% of ESTs, most (70%) of which had atypical patterns representing multiple structural alterations and/or more than one clone. YWHAE and PHF1 rearrangements each occurred in 8% of ESTs. An exceptional case was an ESS without JAZF1 or MEAF6 disruption that further disputes correlation of PHF1 involvement with the sex cord-like variant. These results expand our understanding of the genetic heterogeneity that defines ESTs.

JAZF1/SUZ12 gene fusion in endometrial stromal sarcomas

Endometrial stromal sarcomas (ESSs) belong to the rarest uterine malignancies (prevalence category <1-9/1,000,000). According to the new 2014 World Health Organisation (WHO) classification, they are separated into four categories; benign endometrial stromal nodules (ESNs), low grade endometrial stromal sarcomas (LG-ESSs), high-grade endometrial stromal sarcomas (HG-ESSs) and undifferentiated uterine sarcomas (UUSs). Due to heterogeneous histopathologic appearance these tumors still represent diagnostic challenge, even for experienced pathologists. ESSs are genetically very heterogeneous and several chromosomal translocations and gene fusions have so far been identified in these malignancies. To date the JAZF1/SUZ12 gene fusion is by far the most frequent and seems to be the cytogenetic hallmark of ESN and LG-ESS. Based on present literature data this gene fusion is present in approximately 75 % of ESN, 50 % of LG-ESS and 15 % of HG-ESS cases. The frequency of JAZF1/SUZ12 appearance varies between classic ESS and different morphologic variants. This gene fusion is suggested to become a specific diagnostic tool, especially in difficult borderline cases. In combination with the recently described YWHAE/FAM22 gene fusion the JAZF1/SUZ12 fusion could be used to differentiate between LG-ESS and HG-ESS. The purpose of this review is to summarize literature data published in last two and a half decades about this gene fusion, as a contribution to our understanding of ESS genetics and pathogenesis.

Practical issues related to uterine pathology: endometrial stromal tumors

Uterine mesenchymal tumors continue to be a challenge to diagnose due to their non-specific clinical presentation, often non-distinctive gross appearance, varied (and many times overlapping) morphologic appearance, and unsuspected pitfalls in immunohistochemical expression. This review will focus on endometrial stromal tumors and those features that help in their distinction. In particular, a practical approach to the diagnosis of endometrial stromal neoplasia will be covered including recognition as a stromal process in a biopsy/curettage and distinction from a highly cellular leiomyoma. In addition, distinction of a stromal nodule from a low-grade endometrial stromal sarcoma (LGESS) and stromal sarcoma with limited infiltration in a hysterectomy specimen will be covered. The salient features that help distinguish a LGESS from a uterine tumor resembling ovarian sex-cord tumor as well as high-grade endometrial stromal sarcoma, the latter a tumor recently reintroduced in the WHO classification will also be discussed. Finally, a practical approach to the diagnosis of undifferentiated uterine sarcoma (UUS) will be presented.

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.

High-grade endometrial stromal sarcomas: a clinicopathologic study of a group of tumors with heterogenous morphologic and genetic features

The existence of a "high-grade endometrial stromal sarcoma" category of tumors has been a controversial subject owing to, among other things, the difficulty in establishing consistent diagnostic criteria. Currently, the recommended classification for such tumors is undifferentiated uterine/endometrial sarcoma. Interest in this subject has recently increased markedly with the identification of recurrent molecular genetic abnormalities. At Mayo Clinic, a group of neoplasms has been observed that morphologically resemble, either cytologically or architecturally, classic "low-grade" endometrial stromal sarcoma but feature obvious deviations, specifically, 17 tumors with unequivocally high-grade morphology. These high-grade tumors displayed 3 morphologic themes: (1) tumors with a component that is identical to low-grade ESS that transitions abruptly into an obviously higher-grade component; (2) tumors composed exclusively of high-grade cells with uniform nuclear features but with a permeative pattern of infiltration; (3) tumors similar to the second group but with a different, yet characteristic, cytomorphology featuring enlarged round to ovoid cells (larger than those found in low-grade ESS) with smooth nuclear membranes and distinct chromatin clearing but lacking prominent nucleoli. We collected clinicopathologic data, applied immunohistochemical studies, and also tested tumors by fluorescence in situ hybridization for abnormalities in JAZF1, PHF1, YWHAE, and CCND1. Tumors from these 3 groups were found to be immunohistochemically and genetically distinct from one another. Most notable was the fact that category 3 contained all the cases that tested positive for YWHAE rearrangement, did not show any classic translocations for JAZF1, PHF1, or CCND1, often presented at a high stage, and behaved aggressively. This study demonstrates the morphologic, immunophenotypic, and molecular genetic heterogeneity that exists within "undifferentiated endometrial sarcomas" as currently defined and lends credence to the effort of subclassifying some tumors as truly "high-grade endometrial stromal sarcomas." Our study also shows that, in the context of undifferentiated endometrial sarcomas, recognition of cytomorphologic features on routine hematoxylin and eosin-stained sections may be used to select tumors with specific molecular genetic changes-that is, translocations involving YWHAE. Our conclusions will help further efforts towards proper sub-classification of these tumors which will aid in diagnosis and potentially affect clinical management.

A prognosis based classification of undifferentiated uterine sarcomas: identification of mitotic index, hormone receptors and YWHAE-FAM22 translocation status as predictors of survival

Undifferentiated uterine sarcomas (UUS) are rare tumors with a heterologous biology and a poor prognosis. The goal of this study was to examine clinicopathology, biomarkers and YWHAE-FAM22 translocation status, in the prognosis of these tumors. Twenty-six cases of UUS were included. All original slides were rereviewed and age at diagnosis, tumor stage, "Kurihara" diagnosis, mitotic index, presence of necrosis and grade of nuclear atypia were recorded. Additionally, a tissue microarray was constructed from 22 of the cases, and the protein biomarkers P53, P16, Ki-67, Cyclin-D1, ER, PR and ANLN were evaluated by immunohistochemistry. All tumors were evaluated for the presence of a YWHAE-FAM translocation; the translocation was demonstrated in the three Cyclin-D1 positive tumors. Follow-up data in the form of overall survival were available on all patients. These tumors could be divided into two prognostic groups, a high mitotic index group (10 cases, M = 36.8, SD = 5.4) and a low mitotic index group (16 cases, M = 8.7, SD = 5.8). These two groups showed a statistically significant difference in prognosis. The expression of ER, PR or presence of the YWHAE-FAM22 translocation correlated with low mitotic index and an additionally improved prognosis, although the number of cases was small. These results indicate that UUS can be divided into two prognostic groups using mitotic index as a primary criteria, followed by expression of either ER, PR or the presence of a YWHAE-FAM22 translocation as a secondary criteria. This study demonstrates the presence of statistically significant prognostic subgroups within UUS, and provides treatment insights.

Molecular mechanisms of endometrial stromal sarcoma and undifferentiated endometrial sarcoma as premises for new therapeutic strategies

Endometrial stromal sarcoma (ESS) and undifferentiated endometrial sarcoma (UES) are very rare gynecologic malignancies. Due to the rarity and heterogeneity of these tumors, little is known about their epidemiology, pathogenesis, and molecular pathology. Our previous studies have described deregulation of histone deacetylases expression in ESS/UES samples. Some of these enzymes can be inhibited by substances which are already approved for treatment of cutaneous T-cell lymphoma. On the basis of published data, they may also provide a therapeutic option for ESS/UES patients. Our review focuses on molecular mechanisms of ESS/UES. It describes various aspects with special emphasis on alteration of histone deacetylation and its possible relevance for novel therapies.

Clinical characteristics and outcomes of uterine tumors resembling ovarian sex-cord tumors (UTROSCT): a systematic review of literature

Uterine tumor resembling ovarian sex-cord tumors (UTROSCT) is an extremely rare type of uterine tumor, and its clinical characteristics are not fully understood. A systematic literature search was conducted in PubMed and MEDLINE using the keywords, "uterine tumors resembling ovarian sex cord tumors", limited to case reports. Clinico-pathological characteristics and survival data were abstracted and evaluated for the analysis. Among 43 cases reporting UTROSCT, Type I (endometrial stromal tumors with sex cord-like elements, ESTSCLE) and Type II (classic UTROSCT) were reported in 5 (11.6%) and 17 (39.5%), respectively, and nearly half of reported UTROSCT did not subcategorize the histology pattern into Type I or II (unspecified, n=21, 48.8%). Mean age was 52.2. The two most common symptoms were postmenopausal vaginal bleeding (44.2%) and abnormal menstruation (39.5%). The majority underwent total hysterectomy with adnexectomy (65.1%) followed by hysterectomy alone (18.6%) and tumor resection alone (14.0%). Mean tumor size was 6.2cm, and extra-uterine spread was seen in 7.0%. By immunohistochemistry, calretinin expression was significantly correlated with CAM5.2, inhibin, and progesterone receptor expression (all, p<0.05). In survival analysis, disease-free survival (DFS) rates for all 43 cases at 1, 2, and 5 years for all cases were 97.0%, 92.7%, and 69.7%, respectively. Among recurrent cases, median time to recur was 24 months (range 9-48). Decreased DFS was significantly associated with pelvic pain (2-year rate, 81.8% versus 94.7%, p=0.006), histology subcategory (Type I versus II, 23.8% versus 100%, p=0.006), tumor size ≥10cm (75.0% versus 100%, p=0.046), cervical/extra-uterine metastasis (46.7% versus 100%, p=0.024), and lymphovascular space involvement (50% versus 100%, p=0.002). Treatment patterns were not statistically associated with DFS (hysterectomy, p=0.28; and adnexectomy, p=0.38). When histology patterns were examined, Type II disease was associated with less aggressive tumor behavior when compared to Type I disease: extra-uterine spread (Type I versus II, 40% versus 5.9%, p=0.007) and lymphovascular space invasion (50% versus 6.7%, p=0.012). Among 17 cases of Type II disease, disease recurrence was reported in 1 (5.9%) case at 3 years after the initial treatment. In conclusion, our study showed that UTROSCT was often not subcategorized. Because classic UTROSCT has a distinct clinical outcome and characteristic histological patterns when compared to ESTSCLE, distinguishing UTROSCT from ESTSCLE is an integral component of the diagnosis. While classic UTROSCT typically has a favorable prognosis, it has been known to develop a late recurrence. If risk factors for recurrence are absent, both hysterectomy and mass resection alone are possible options for management.

Uterine tumors resembling ovarian sex cord tumors

Uterine tumors resembling ovarian sex cord tumors (UTROSCT) are rare neoplasms of unknown etiology. Only 67 cases have been reported in the literature, to our knowledge, so far. The neoplasm usually occurs in middle-aged women. Most patients present with abnormal uterine bleeding and/or abdominal pain, along with an enlarged uterus or a palpable uterine mass. There is no specific imaging finding, and the diagnosis is made exclusively on histopathologic examination. A multitude of architectural patterns are described, which include plexiform cords, anastomosing trabeculae, watered-silk, microfollicle, macrofollicle, tubules, retiform, solid cellular islands, and diffuse pattern of growth. The neoplastic cells are usually small with round to ovoid nuclei, nuclear monotony, mild nuclear hyperchromasia, and inconspicuous nucleoli with scant eosinophilic cytoplasm. Nuclear grooves are rare. Mitotic figures are infrequent, and necrosis is mostly absent. This tumor depicts a diverse immunohistochemical profile with expression of sex cord, epithelial, and smooth muscle lineages markers. Sex cord markers, such as inhibin, calretinin, CD99, WT1, and MART-1; epithelial markers, such as pancytokeratin and epithelial membrane antigen; smooth muscle markers, such as smooth muscle actin, desmin, and histone deacetylase 8; and miscellaneous markers, such as CD10, estrogen receptor, progesterone receptor, S100, and CD117, are often coexpressed. Immunoexpression for calretinin and at least for one of the other sex cord markers is required to establish a diagnosis of UTROSCT. Hysterectomy with or without bilateral salpingo-oophorectomy is usually the treatment for UTROSCT. Although most UTROSCTs behave benignly, some do recur, and thus, this entity should be considered as a tumor of low malignant potential. In this review, we discuss the current knowledge on UTROSCT and its clinical relevance.

Diagnosis of endometrial stromal tumors: a clinicopathologic study of 25 biopsy specimens with identification of problematic areas

OBJECTIVES

To assess the difficulties associated with diagnosing endometrial stromal tumors (ESTs) on endometrial biopsy.

METHODS

We examined 25 endometrial biopsy specimens from 19 consecutive women diagnosed with either endometrial stromal nodule (n = 3) or endometrial stromal sarcoma (n = 16).

RESULTS

Rereview of the biopsy specimens revealed a stromal fragment suspicious for an EST in 16, of which eight had received a benign diagnosis on initial review. Most ESTs had an aglandular stromal fragment that was 5 mm or larger. Stromal fragments of this size were not encountered in the control material. Problematic areas included highly cellular leiomyoma and a lack of attention to the stromal compartment.

CONCLUSIONS

Most endometrial stromal tumors present with large aglandular stromal fragments (≥5 mm). These fragments are large enough that difficulties in diagnosis appear to be due to a lack of attention to the stromal compartment.

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.

Endometrial sarcomas: an immunohistochemical and JAZF1 re-arrangement study in low-grade and undifferentiated tumors

The current World Health Organization classification divides endometrial sarcomas into low-grade endometrial stromal sarcoma and undifferentiated endometrial sarcoma. Recent studies suggest undifferentiated endometrial sarcoma is a heterogeneous group and a subgroup with uniform nuclei is more akin to low-grade endometrial stromal sarcoma in terms of morphologic, immunohistochemical and genetic features. We classified endometrial sarcomas treated at our institution from 1998 to 2011 into low-grade endometrial stromal sarcoma and undifferentiated endometrial sarcoma, the latter being further categorized into a group with either uniform or pleomorphic nuclei. Morphological features, immunoprofile and fluorescence in situ hybridization rearrangements of JAZF1 and PHF1 genes were correlated with tumor category and outcome. A total of 40 cases were evaluated comprising 23 low-grade endometrial stromal sarcomas, 10 undifferentiated endometrial sarcomas with nuclear uniformity and 7 undifferentiated endometrial sarcomas with nuclear pleomorphism. Low-grade endometrial stromal sarcomas were more often estrogen and progesterone receptor positive (83%) compared with undifferentiated endometrial sarcoma with nuclear uniformity (10%) or with nuclear pleomorphism (0%) (P<0.001). Positivity for p53 was restricted to undifferentiated endometrial sarcomas with more frequent expression in the group with nuclear pleomorphism (57%) than with nuclear uniformity (10%) (P=0.06). Ki-67 proliferation index in >10% of tumor cells more frequent in undifferentiated endometrial sarcoma than low-grade endometrial stromal sarcoma (P=<0.001). JAZF1 rearrangement was detected in 32% of low-grade endometrial stromal sarcomas and in none of the undifferentiated sarcomas. Rearrangement of PHF1 was found in two patients, one with JAZF1-PHF1 fusion. There were no significant differences in clinical behavior between undifferentiated endometrial sarcoma with nuclear uniformity versus nuclear pleomorphism. In conclusion, we found undifferentiated endometrial sarcoma subtypes and low-grade endometrial stromal sarcoma have distinct immunohistochemical and cytogentic profiles. Our data do not show any difference in clinical behavior between subgroups in undifferentiated sarcomas.

Cyclin D1 as a diagnostic immunomarker for endometrial stromal sarcoma with YWHAE-FAM22 rearrangement

Endometrial stromal sarcoma (ESS) characterized by YWHAE-FAM22 genetic fusion is histologically higher grade and clinically more aggressive than ESS with JAZF1-SUZ12 or equivalent genetic rearrangements, hence it is clinically important to recognize this subset of ESS. To identify diagnostic immunomarkers for this biologically defined ESS subset, we compared gene expression profiles between YWHAE-FAM22 ESS and JAZF1-rearranged ESS. These studies showed consistent upregulation of cyclin D1 in YWHAE-FAM22 ESS compared with JAZF1-SUZ12 ESS. Immunohistochemically, the high-grade round cell component of all 12 YWHAE-FAM22 ESS demonstrated diffuse (≥70%) moderate to strong nuclear cyclin D1 staining, and this diffuse positivity was not seen in 34 ESSs with JAZF1 and equivalent genetic rearrangements or in 21 low-grade ESS with no demonstrable genetic rearrangements. In a series of 243 non-ESS pure uterine mesenchymal and mixed epithelial-mesenchymal tumors, only 2 of 8 undifferentiated endometrial sarcomas with nuclear uniformity and 1 of 80 uterine leiomyosarcomas demonstrate diffuse cyclin D1 immunoreactivity. Both cyclin D1-positive undifferentiated endometrial sarcomas showed diffuse strong CD10 staining, which is consistently absent in the high-grade round cell component of YWHAE-FAM22 ESS. The low-grade spindle cell component of YWHAE-FAM22 ESS showed a spatially heterogenous cyclin D1 staining pattern that was weaker and less diffuse overall. Our findings indicate that cyclin D1 is a sensitive and specific diagnostic immunomarker for YWHAE-FAM22 ESS. When evaluating high-grade uterine sarcomas, cyclin D1 can be included in the immunohistochemical panel as an indicator of YWHAE-FAM22 ESS.