Cytogenetic and molecular genetic analyses of endometrial stromal sarcoma: nonrandom involvement of chromosome arms 6p and 7p and confirmation of JAZF1/JJAZ1 gene fusion in t(7;17)

Endometrial stromal sarcomas (ESS) are rare neoplasms with the capacity both to invade the myometrium locally and to give rise to extrauterine metastases. Cytogenetic abnormalities have been reported in 22 cases of ESS, mostly involving rearrangements of chromosomes 6, 7, and 17. The most characteristic translocation of this tumor type, t(7;17)(p15 approximately p21;q12 approximately q21), was recently shown to generate a JAZF1/JJAZ1 fusion gene. We report three additional cases of ESS with abnormal karyotypes, whose interpretation was based on the combined analysis by conventional cytogenetics and cross-species color banding FISH (RxFISH). The combination of G-banding and RxFISH in every case gave additional information beyond that obtained by either technique alone, determining the identity of even complex inter- as well as intrachromosomal rearrangements. In one of the three tumors, a t(7;17) was seen; molecular genetic studies identified the JAZF1/JJAZ1 fusion gene in this case. Two tumors had aberrations that included structural changes of chromosome arms 6p and 7p. Evidently, karyotypic, and hence pathogenetic, heterogeneity exists for tumors classified as endometrial stromal sarcomas based on their phenotypic features.     

Colonic low‐grade endometrial stromal sarcoma and orthotopic endometrial stromal tumor with limited infiltration sharing the JAZF1‐SUZ12 gene fusion

Endometrial stromal tumors (ESTs) are composed of cells resembling endometrial stroma, and are divided into benign and malignant types based on morphology. Endometrial stromal nodule (ESN) is a benign localized tumor, and endometrial stromal sarcoma (ESS) is an infiltrative and potentially metastatic neoplasm. A series of genetic aberrations contribute to pathological diagnosis of ESTs. At present, subsets of ESN and ESS‐low grade (ESS‐LG) are characterized as JAZF1‐SUZ12/JJAZ1 gene fusion. The ESTs that show higher grade atypia but lack nuclear pleomorphism include YWHAE‐FAM22 ESS. Here we report an unusual case of ESTs. Sudden colonic perforation occurred to the patient, and emergency surgery was performed. Pathological findings suggested metastatic ESS. Thorough medical examination of the genital organs detected a 1 cm‐sized well‐demarcated uterine tumor. Microscopically, the tumor lacked infiltrative features, conforming to the definition of ESN. Both lesions demonstrated identical cytology and shared JAZF1‐SUZ12 gene fusion. Endometriosis was not found in any areas of the resected organs, strongly suggesting that the uterine orthotopic tumor metastasized. The current case uncovered the problems of differential diagnosis between ESN and ESS‐LG. We demonstrate detailed pathological features of the two lesions, and discuss the possibility of orthotopic EST with limited infiltration to develop into ESS‐LG.     

Extra-uterine low grade stromal sarcoma with JAZF1–PHF1 gene fusion presenting as a mesenteric mass

This case illustrates a low-grade endometrial stromal sarcoma presenting as an intra-abdominal mass. Intra-operatively, this was thought to arise within the mesentery and was classified as a mesenteric tumour. The solid and cystic mass was composed of relatively uniform cells organized in sheets. Up to 8 mitoses per high power field was noted. The stroma although scanty, contained both delicate capillary-type and more arteriolar-like vessels. Admixed with the tumour cells were smaller cells reminiscent of endometrial stromal granulocytes. The tumour was positive for: WT1, oestrogen receptor (ER), CD10, vimentin, and focally for progesterone receptor (PR), and very occasional cells for smooth muscle actin. Fluorescence in situ hybridization (FISH) showed the presence of JAZF1 and PHF1 genetic rearrangement.This confirmed a diagnosis of extra-uterine low-grade endometrial stromal sarcoma. It is unsure whether this represents a primary or secondary lesion as the patient had a previous hysterectomy for unknown pathology.     

Molecular genetic changes in epithelial, stromal and mixed neoplasms of the endometrium

Endometrial carcinoma, endometrial stromal tumours and mixed malignant mesodermal tumours (MMMT) develop along distinctive molecular genetic pathways. Two distinctive types of endometrial carcinoma are distinguished, type I and type II, which develop along distinctive pathways and show different clinical behaviour and histological features. Type I carcinomas show endometrioid histology, are oestrogen-related and develop from atypical endometrial hyperplasia. The molecular tumorigenesis is comparable to colorectal carcinoma with a step-like progression and an accumulation of genetic alterations. Alterations of PTEN, K-Ras mutations and microsatellite instability are frequent and early events in type I carcinoma, whereas p53 mutations occur during progression to grade 3 carcinoma. Serous and clear cell carcinomas are considered type II carcinomas which are mostly unrelated to oestrogen. p53 mutations occur in almost all serous carcinomas and seem to occur early, leading to massive chromosomal instability and rapid tumour progression. Gene expression profiling has supported this dualistic model of endometrial carcinoma. There is evidence of molecular differences between serous and clear cell carcinomas as well as between endometrioid carcinomas with and without microsatellite instability. A dualistic model of tumorigenesis may be also suggested for endometrial stromal tumours. Endometrial stromal sarcomas (ESS; type I endometrial sarcoma) are oestrogen-related and seem to develop from endometrial stromal nodules (ESN). They are histologically and genetically distinct from undifferentiated endometrial sarcoma (UES) which seem to be mostly unrelated to oestrogen (type II endometrial sarcoma). ESS and ESN share the fusion gene JAZF1/JJAZ1 caused by a t(7;17)(p15;q21) translocation, whereas UES lacks a distinctive molecular alteration so far. In MMMT, which is considered a metaplastic carcinoma, p53 alteration occurs early, before clonal expansion and acquisition of genetic diversity during progression.     

Endometrial stromal tumor with limited infiltration and probable extrauterine metastasis: report of a case

Endometrial stromal nodule (ESN) is a tumor composed of cells closely resembling those of the endometrial stroma with minimal cytologic atypia. The most important criterion for the differential diagnosis from the endometrial stromal sarcoma (ESS) is a well-defined noninfiltrative expansile border. However, the definition of the ESN also includes a tumor with the presence of focal irregularities or fingerlike projections of the margin into the adjacent myometrium, none of which exceeds 2 to 3 mm. In some cases, however, it is difficult to differentiate marginal irregularities of ESN from "true invasion" of ESS. We described a case of extrauterine ESS that was associated with small intramyometrial stromal lesions with limited infiltration. The intramyometrial lesion could be definitionally categorized as ESNs. However, peritumoral fibroblastic band and inflammatory stromal reactions, irregular fingerlike projections, and multiple concurrent extrauterine ESS strongly suggested that these were small primary focus of ESS mimicking ESN. We propose that the patient with endometrial stromal tumor with limited infiltration should be more carefully followed than the usual ESN for possible metastasis and that a hysterectomy with meticulous histological examination of the specimen be performed before a diagnosis of primary extrauterine ESS is made, even in a case showing a grossly or radiologically normal uterus.     

Aspiration biopsy cytology of metastatic endometrial stromal sarcoma and extragenital mixed mesodermal tumor

Aspiration biopsy from metastatic tumors in two cases of endometrial stromal sarcoma and one case of endometrial adenosarcoma revealed malignant endometrial stromal cells with ill-defined cytoplasm and round or oval hyperchromatic nuclei showing irregular chromatin clumping and conspicuous nucleoli. They were seen mainly in clusters. Aspirate from a metastatic tumor of a mixed mesodermal tumor arising from the omentum showed similar malignant endometrial stroma cells, irregular tight clusters of malignant glandular cells having scanty but well-defined cytoplasm and vesicular nuclei with conspicuous nucleoli, and fragments of atypical smooth muscle tissue. The diagnostic malignant endometrial stromal cells in those reported cases did not display any distinctive cellular features permitting their cytologic identification. They were difficult to differentiate from those of other types of sarcoma. In a clinical setting, with a known primary endometrial stromal sarcoma or mixed mesodermal tumor, however, a cytodiagnosis of its metastases may be suggested when malignant endometrial stromal-cell-like cells are seen in aspirated material, oviating an open-tissue biopsy.     

Distinction of endometrial stromal sarcomas from 'hemangiopericytomatous' tumors using a panel of immunohistochemical stains.

Endometrial stromal sarcomas are low-grade malignant tumors that may pose a diagnostic challenge, especially when they are present in an extrauterine site. Owing to the presence of an arborizing vasculature and cells with an undifferentiated appearance, endometrial stromal sarcomas can be confused with several soft-tissue neoplasms. We studied 17 endometrial stromal sarcomas, eight hemangiopericytomas, 14 solitary fibrous tumors, and 16 synovial sarcomas immunohistochemically, detecting the following antigens: CD10, estrogen receptor, progesterone receptor, bcl-2, CD34, smooth muscle antigen, epithelial membrane antigen and cytokeratin (AE1/AE3). Most endometrial stromal sarcomas stained positively for CD10 (16/17), estrogen receptor (17/17), progesterone receptor (15/17), and bcl-2 (17/17). Staining with antismooth muscle antigen was seen in 11 of 17 cases of endometrial stromal sarcoma, with more intense staining seen in areas showing smooth muscle differentiation. Staining with AE1/3 was seen in four of 17 endometrial stromal sarcomas, with two of the positive cases containing epithelioid cells. None of the endometrial stromal sarcomas expressed epithelial membrane antigen or CD34. More than half of the hemangiopericytomas (4/8) and solitary fibrous tumors (9/14) cases demonstrated CD10 expression either focally or in a patchy cytoplasmic and membranous pattern. Hemangiopericytomas, solitary fibrous tumors, and synovial sarcomas did not express estrogen receptor. Four of eight hemangiopericytomas and seven of 14 solitary fibrous tumors also showed patchy progesterone receptor expression. CD34 expression was identified in six of eight hemangiopericytomas and 13 of 14 solitary fibrous tumors, but we did not find expression of CD34 in synovial sarcoma. Differences between endometrial stromal sarcoma and other soft-tissue tumors were detected for all of the immunohistochemical markers (P<0.05), except anti-bcl-2 and AE1/3. Antibodies against CD10 mark a substantial number of hemangiopericytomas and solitary fibrous tumors (albeit not diffusely) and should always be combined with antiestrogen receptor and CD34 when the differential diagnosis includes endometrial stromal sarcoma. Unlike estrogen receptor antibodies, progesterone receptor antibodies show at least focal nuclear staining in most hemangiopericytomas, solitary fibrous tumors and rare synovial sarcomas, and are not useful for this differential diagnosis. All endometrial stromal sarcomas expressed bcl-2, mostly in a diffuse pattern, but this did not distinguish between endometrial stromal sarcoma and mimics. We therefore recommend the use of a small antibody panel comprising anti-CD10, anti-estrogen receptor, and anti-CD34 to distinguish endometrial stromal sarcomas from tumors with a predominant hemangiopericytomatous growth pattern.     

Uterine endometrial stromal sarcoma with rhabdoid and smooth muscle differentiation.

Uterine and extrauterine tumors composed of cells featuring endometrial stromal cells often show ovarian sex cord-like structures and smooth muscle differentiation. A few cases of endometrial stromal tumors showing rhabdoid differentiation have been reported. The present case is a 20-year-old woman with endometrial stromal sarcoma that had sex cord-like structures, smooth muscle components and rhabdoid differentiation.     

Endometrial stromal sarcoma of the sigmoid colon arising in endometriosis: a case report with a review of literatures

Most of malignant tumors arising in ovarian and extraovarian endometriosis are carcinomas. Mixed mullerian tumor and endometrial stromal sarcoma arising in intestinal endometriosis are rarely described, but its clinicopathologic features have not been well characterized. Here we report a case of endometrial stromal sarcoma of the sigmoid colon arising in endometriosis with a review of six additional cases of endometrial stromal sarcoma arising in intestinal endometriosis found in English literatures. The patients ranged in age from 36 to 64 yr. Presenting symptoms were pain, bloody diarrhea, and tenesmus. Some patients had a previous history of endometriosis. Most of the tumors arose in the rectosigmoid colon. The histologic features were the same as their uterine counterpart. No death of disease had been reported. This rare tumor should not be confused with gastrointestinal stromal tumor clinically and histologically.     

Endometrial stromal sarcoma – the new genetic paradigm

Endometrial stromal sarcoma (ESS) is a gynaecological sarcoma that is composed of cells that resemble those of proliferative‐phase endometrial stroma. The 2014 World Health Organization tumour classification system separates ESS into low‐grade and high‐grade types, which are histologically, genetically and clinically distinct from undifferentiated uterine sarcoma (UUS). Low‐grade ESSs frequently contain chromosomal rearrangements that result in JAZF1–SUZ12 fusion or equivalent genetic fusions. Although most low‐grade ESSs show classic histological features that closely resemble those of proliferative‐phase endometrial stroma, there are several histological variants that are associated with the same genetic fusions as seen in the classic type. High‐grade ESS is defined by the presence of YWHAE–NUTM2A/B (YWHAE–FAM22A/B) fusions. High‐grade ESSs are clinically more aggressive than low‐grade ESSs, but are associated with a lower mortality rate than UUSs. The histological and immunophenotypic features of these different types of ESS, and their diagnostic considerations, are the subjects of this review.     

Mixed endometrial stromal and smooth muscle tumor: Report of a case with focal anaplasia and early postoperative lung metastasis

A rare case of a mixed endometrial stromal and smooth muscle tumor arising in the uterus of a 74‐year‐old woman is reported. The patient underwent hysterectomy for an enlarging uterine mass, and a large intramural tumor, showing marked central hyaline necrosis with calcification, was found. The tumor consisted of an admixture of a low‐grade endometrial stromal sarcoma (ESS) and a fascicular proliferation of spindle cells suggesting smooth muscle differentiation, and a characteristic ‘star‐burst’ appearance was found. In the ESS region, there were a few small foci of anaplasia where large polygonal cells with atypical nuclei and abundant eosinophilic cytoplasm proliferated, and the proliferative activity was locally increased in these foci. A small metastatic nodule appeared in the lung nine months after the hysterectomy, and the resected metastatic lesion showed features of anaplastic spindle cell sarcoma which was immunoreactive for CD10 but not for smooth muscle markers. Mixed endometrial stromal and smooth muscle tumors should be regarded as malignant neoplasms with the potential for hematogenous metastasis, particularly when they contain foci of cellular anaplasia.     

Endometrial stromal tumors: an update on a group of tumors with a protean phenotype

Endometrial stromal tumors are reviewed with emphasis on their wide morphologic spectrum and problems in differential diagnosis, highlighting issues that have received particular attention in the recent literature. These neoplasms are divided into two major categories--endometrial stromal nodules and endometrial stromal sarcomas--a distinction made on the basis of the lack of significant infiltration at the periphery of the former. The division of endometrial stromal sarcomas into low-grade and high-grade categories has fallen out of favor and the designation endometrial stromal sarcoma is now considered best restricted to neoplasms that were formally referred to as "low-grade" stromal sarcoma. Endometrial sarcomas without recognizable evidence of a definite endometrial stromal phenotype, designated poorly differentiated "endometrial sarcomas," are almost invariably high grade and often resemble the mesenchymal component of a malignant mullerian mixed tumor. Two features of endometrial stromal tumors that may cause confusion are smooth muscle differentiation and epithelial patterns. Cases in the former category often have a characteristic "starburst" pattern of collagen formation. The most common epithelial patterns resemble those seen in ovarian sex-cord stromal tumors. Much less common is endometrioid gland differentiation. Some endometrial stromal tumors have a prominent fibrous or myxoid appearance and the myxoid tumors should be distinguished from myxoid leiomyosarcoma. Other unusual features of endometrial stromal tumors are also discussed. Lesions in the differential diagnosis of uterine endometrial stromal neoplasms include highly cellular leiomyoma, cellular intravenous leiomyomatosis, adenomyosis with sparse glands, metastatic carcinoma, and lymphoma. Endometrial stromal sarcomas at extrauterine sites may be primary or metastatic from a uterine tumor, the latter sometimes being occult and difficult to definitively establish, particularly if there is a history of a remote hysterectomy for "leiomyomas." Endometrial stromal sarcomas of the ovary, whether primary or metastatic, may be difficult to distinguish from ovarian sex-cord stromal tumors. Extragenital endometrial stromal sarcomas may be confused with diverse lesions such as gastrointestinal stromal tumors, hemangiopericytoma, lymphangiomyomatosis, or mesenchymal cystic hamartoma of the lung. Immunohistochemistry may play a role in evaluating these tumors and in some instances establishing the diagnosis although conventional light microscopic analysis suffices in the majority of cases. The unusual tumor, the "uterine tumor resembling an ovarian sex-cord tumor," is also considered in this review as it is almost certainly of endometrial stromal derivation in many cases. These neoplasms may have a striking resemblance to granulosa cell tumors or Sertoli cell tumors, including those with a retiform pattern, and have recently been shown to be frequently inhibin positive.     

Myxoid endometrial stromal sarcoma of the uterus

A rare case of a myxoid type of endometrial stromal sarcoma of the uterus in a 41-year-old woman is reported. A tumor was found in the myometrium and was well circumscribed, measuring 9 x 7 x 7 cm in size. The tumor was mainly composed of a hypocellular area with tumor cells separated by prominent myxoid stroma. The tumor cells were spindle-shaped and resembled endometrial stromal cells. Numerous small thin-walled vessels were seen throughout the tumor. Immunohistochemically, the tumor cells were diffusely stained for estrogen and progesterone receptors and CD10, and focally and weakly for HHF35, alpha-smooth muscle actin and desmin, but not stained for h-caldesmon. These results indicated that the tumor originated from endometrial stromal cells. The tumor had an increased mitotic activity (MIB-1 labeling index: 1-10%), and focally showed nuclear pleomorphism. Thus, this tumor had a malignant potential and was diagnosed as a myxoid type of low-grade endometrial stromal sarcoma. The patient is currently well with no evidence of local recurrence or metastasis 21 months after the operation. This case indicates a wide morphological spectrum of endometrial stromal tumor. A myxoid endometrial stromal sarcoma should be considered in the different diagnosis of the intramural myxoid tumors in the uterus.     

Endometrial stromal sarcoma of the small bowel

Endometrial stromal sarcoma (ESS) is a rare mesenchymal neoplasm of the uterus, which is predominantly composed of endometrial stromal cells. When this feature is encountered in the extragenital area, the diagnosis is sometimes difficult especially if endometriosis is not present. We report a case of ESS arising in the small bowel without associated endometriosis in a 75-year-old woman and review the literatures for 16 cases of extrauterine extraovarian ESS. The most common site of the extrauterine extraovarian ESS is the gastrointestinal tract (8/16 cases). It is intimately associated with endometriosis (12/16 cases) as the case of ovarian ESS. Most ESSs were immunoreactive for CD10 (5/5 cases), progesterone receptor (10/10 cases), and estrogen receptor (9/11 cases), and negative for CD34 (0/7 cases). It may have a higher tendency for dissemination beyond its site of origin (12/16 cases) than its uterine counterpart. In conclusion, a careful morphological examination combined with immunohistochemical studies and consideration of ESS in the differential diagnosis would help in obtaining an accurate diagnosis in these rare circumstances.     

Cytogenetic and molecular aberrations in endometrial stromal tumors

Endometrial stromal tumors (ESTs) are rare uterine mesenchymal tumors, comprising <10% of all uterine mesenchymal neoplasms. The latest World Health Organization classification divides endometrial stromal tumors into 3 categories based on morphologic features: endometrial stromal nodule (ESN), low-grade endometrial stromal sarcoma, and undifferentiated endometrial sarcoma. Specific cytogenetic aberrations and molecular genetic alterations have recently been identified in endometrial stromal tumors, providing insights into their molecular biology, potential diagnostic markers, and possible therapeutic targets. Currently, recurrent chromosomal rearrangements resulting in gene fusion play a substantive role in the pathogenesis of endometrial stromal nodules, endometrial stromal sarcomas, and a small subset of undifferentiated endometrial sarcomas. Loss of heterozygosity of tumor suppressor genes and deregulation of the Wnt signaling pathway have also been implicated in EST tumorigenesis. In this review, we summarize the recent advances in the molecular pathology of endometrial stromal tumors.     

Novel SS18‐NEDD4 gene fusion in a primary renal synovial sarcoma

We report a primary renal synovial sarcoma with a novel gene fusion and unusual morphology. The patient was a 35‐year‐old female who was found to have a 5 cm hypocellular, myxoid spindle cell renal neoplasm that subtly permeated amongst native renal tubules. The tumor cells showed elongated hyperchromatic nuclei with ill‐defined pale cytoplasm, lacking significant mitotic activity or necrosis. Based on its deceptively bland morphology, the differential diagnosis included mainly benign entities, such as metanephric stromal tumor, mixed epithelial stromal tumor (MEST), and myxoid peripheral nerve sheath tumors. A definitive diagnosis of synovial sarcoma was made only subsequently to RNA‐sequencing, which revealed a novel SS18‐NEDD4 gene fusion. These results were further confirmed by fluorescence in situ hybridization using custom design break‐apart probes for both genes. This case illustrates the utility of targeted RNA‐sequencing in the classification of challenging tumors with deceptive morphology and identification of novel gene fusion variants. Apart from the canonical SS18‐SSX fusion, this is only the second alternative gene fusion variant described in synovial sarcoma to date, in addition to two cases harboring the SS18L1‐SSX1 fusion.     

Reticular angiomatoid "malignant" fibrous histiocytoma--a case report with cytogenetics and molecular genetic analyses

Angiomatoid "malignant" fibrous histiocytoma is a rare sarcoma of low malignant potential that occurs most commonly in the extremities of children and young adults. Herein, we present a case of angiomatoid malignant fibrous histiocytoma with unusual histologic features arising in the mediastinum of an 80-year-old man. The tumor exhibited a reticular growth pattern and myxoid stroma. The tumor cells expressed epithelial membrane antigen and desmin. Cytogenetic analysis revealed the translocation t(2;22)(q33;q12). Molecular genetic analysis confirmed the rearrangement of the EWSR1 locus and the presence of the EWSR1/CREB1 fusion. This report expands the clinicopathologic spectrum of angiomatoid malignant fibrous histiocytoma and underscores the value of integrating morphologic, immunophenotypic, and molecular findings in the identification of its unusual morphologic variants.     

Mixed low grade and high grade endometrial stromal sarcoma of uterus: differences on immunohistochemistry and chromosome in situ hybridisation.

A case of a 64 year old woman with a tumour of the uterus is reported. The patient presented with postmenopausal bleeding and subsequently underwent total hysterectomy and bilateral salpingo-oophorectomy. Sections of the tumour showed a low grade endometrial stromal sarcoma coexisting with areas consistent with high grade sarcoma. The sarcoma cells, in both the low and high grade areas, were positive for vimentin and negative for desmin and cytokeratin on immunohistochemistry. While the sarcoma cells in the low grade region showed immunoreactivity for oestrogen and progestogen receptors, those in the high grade region did not. Using chromosome in situ hybridisation, the low grade portion of the sarcoma was diploid for chromosomes X, 11, 12, and 17, whereas the more anaplastic areas were aneuploid for these chromosomes. This case may represent an example of high grade endometrial stromal sarcoma arising by dedifferentiation from a low grade stromal sarcoma. Adequate sampling is important in identifying such anaplastic changes as the origin of the tumour will affect patient management.