BACKGROUND: Endometrial stromal sarcoma is an extremely rare mesenchymal neoplasm occurring in the extrauterine. Retroperitoneal endometrial stromal sarcoma with multiple pulmonary metastases, in particular, is extremely rare.
METHODS: Forty-seven-year-old woman (gravida 3, para 2), was referred to our institution with complaints of fever.
METHODS: Ultrasound and computed tomographic imaging of the abdomen identified the presence of masses in the pelvic region. Additionally, computed tomographic scans and X-ray evaluations of the thorax detected dispersed masses in both the lungs and pelvic area. Histopathological analysis of the pelvic region indicated the presence of low-grade endometrial stromal sarcoma. A computed tomography-guided pneumocentesis was conducted to further characterize the pulmonary lesions, confirming the diagnosis of low-grade endometrial stromal sarcoma.
METHODS: The patient underwent tumor resection, subsequent treatment with Medroxyprogesterone acetate for 6 months, received microwave ablation for multiple lung metastases, PARP1 inhibitor for 4 courses, and has been undergoing chemotherapy (epirubicin/ifosfamide) up to the present time.
RESULTS: Partial remission was obtained after the above treatment and this patient is now still alive maintaining for 3 years.
CONCLUSIONS: The identification and management of this disease remain a significant challenge due to its low prevalence. Further research involving a larger number of cases is necessary to ensure consistency in diagnosis and to establish effective treatment guidelines.

BACKGROUND: High-grade endometrial stromal sarcoma (HG-ESS) is a rare malignant tumor with poor prognosis. To overcome the limitations of current treatment for advanced patients, the intervention of targeted drug therapy is urgently needed.
METHODS: A 74-year-old married woman who presented with abdominal distension and lower abdominal pain was admitted to Hebei General Hospital. After surgery, immunohistochemical staining revealed a malignant tumor which was consistent with HG-ESS. Tumor recurrence occurred 2 months after surgery. Then the patient underwent chemotherapy with two courses but responded poorly. Subsequently we observed ATM, BLM, and CDH1 co-mutations by Next Generation Sequencing (NGS). Then the patient received pamiparib, which resulted in a 10-month progression-free survival (PFS) and is now stable with the administration of sintilimab in combination with pamiparib and anlotinib.
CONCLUSIONS: Due to the successful use of poly ADP-ribose polymerase inhibitor (PARPi) on HG-ESS, we suggest that the selection of effective targeted drugs combined with anti- programmed death-1 (PD-1) drug therapy based on genetic testing may become a new option for the treatment of homologous repair deficient (HR-deficient) HG-ESS.

BACKGROUND: Endometrial stromal tumors (ESTs) are rare subset of mesenchymal uterine neoplasms. There are heterogeneous morphological, immunohistochemical, and genetic features. Approximately 50% of ESTs occur in perimenopausal women. In 2020, WHO sub-categorized ESTs into four groups: endometrial stromal nodule (ESN), low-grade endometrial stromal sarcoma (LGESS), high-grade endometrial stromal sarcoma (HGESS), and undifferentiated uterine sarcoma (UUS).
OBJECTIVE: To review the morphological spectrum of endometrial stromal tumors.
METHODS: This retrospective study reviewed the histomorphological features of 15 endometrial stromal tumors with respect to atypia, necrosis, mitosis, collagen bands, whorling around vessels, myometrial invasion, and inflammatory cells. Immunohistochemistry markers (CD10, SMA, and ER) along with special stains (Masson\'s trichrome, toluidine blue) were also studied.
RESULTS: The age of the patients ranged from 32 to 60 years. Three patients were postmenopausal. The most common presenting symptom was vaginal bleeding. Five patients were operated with a clinical diagnosis of uterine fibroid. One patient presented with prolapse with no other complaint. All the 15 patients had total abdominal hysterectomy and salpingo-oophorectomy. One case showed necrosis, eight cases showed collagen bands, all the 15 cases showed whorling around vessels, one case showed vascular emboli, and seven cases showed inflammatory cells. In low-grade cases, one case showed focal atypia and one case showed focal coagulative necrosis indicating infarction. Thirteen cases were LGESS, and one case of ESN and HGESS. All cases were positive for ER and CD10.
CONCLUSIONS: Endometrial stromal tumors demonstrate extensive permeation of the myometrium as irregular islands with frequent vascular invasion, whorling around vessels, collagen bands, and inflammatory cells. All these features should be observed thoroughly on microscopy by pathologists to clearly differentiate the low-grade and high-grade endometrial stromal tumors, and to understand the overlapping gray areas morphologically as it affects the prognosis of the patient.

High-grade endometrial stromal sarcomas with ZC3H7B-BCOR fusion are rare. They are predominantly located in the endomyometrium, with morphologic features characterized as haphazardly arranged fascicles of spindle cells with mild to moderate atypia, abundant myxoid matrix, high mitotic index, and tongue-like/pushing patterns of myometrial invasion. Furthermore, conventional or variant low-grade endometrial stromal sarcomas are often not present. Clinically, they present at a higher stage and are associated with worse prognosis compared with low-grade endometrial stromal sarcoma. Given the limited number of reported cases, we describe the case of a ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma initially diagnosed on the hysterectomy specimen as low-grade endometrial stromal sarcoma based on an endometrial stromal tumor showing tongue-like myometrial and lymphovascular invasion, minimal cytologic atypia, low-mitotic activity (0-1/10 high-power field), round/spindle cell component and immunohistochemical stain results (positive for CD10, estrogen receptor, progesterone receptor, and focally positive for cyclin D1). At the time of pathologic diagnosis, she was Stage Ia and managed conservatively. Subsequent molecular analysis revealed a ZC3H7B (exon 10)- BCOR (BCL-6 corepressor) (exon 7) gene fusion. On follow-up, she showed no evidence of disease at 37 months from the time of diagnosis. This case report expands the morphologic spectrum of ZC3H7B-BCOR fusion high-grade ESS, which includes an intramural location, morphologic and immunophenotypic features similar to LG-ESS, as well as the presence of round and spindle cell components. This case also underscores the value of molecular analysis in the proper classification of ESS.

Low-grade and high-grade endometrial stromal sarcomas (LGESS and HGESS) and undifferentiated uterine sarcomas (UUS) are rare tumors whose pathological classification and staging system have changed recently. These tumors are reported to contain fusion genes. We aimed to clarify the genetic background, clinical features, prognostic factors, and optimal therapy of these tumors using a new classification and staging system.
We analyzed the clinical features and prognostic information of 72 patients with LGESS, 25 with HGESS, and 16 with UUS using central pathological review. Estrogen and progesterone receptors (PgRs) were examined by immunohistochemistry. JAZF1-SUZ12 and YWHAE-NUTM2A/B gene fusions were tested using real-time polymerase chain reaction.
The 5-year overall survival (OS) rates of LGESS, HGESS, and UUS were 94%, 53%, and 25%, respectively. In LGESS, stage IV, incomplete surgery, and absence of PgR were associated with poor OS. The presence of JAZF1-SUZ12 fusion gene was not associated with OS. In HGESS, the relationship between stage and prognosis was unclear. None of the 3 patients with YWHAE-NUTM2A/B fusion gene died during follow-up. Adjuvant chemotherapy was associated with a favorable OS. Incomplete resection of UUS was associated with poor OS; however, residual tumors frequently occurred. Although most patients underwent adjuvant chemotherapy, their prognosis was extremely poor even in stage I disease.
Prognosis of LGESS is generally good; however, stage IV, incomplete surgery, and PgR-negative tumors are associated with poor prognosis. Adjuvant chemotherapy may be useful for HGESS. Prognosis of UUS is extremely poor, even with adjuvant chemotherapy.

MEIS1::NCOA1/2 fusion sarcomas are a recently described novel entity arising in a variety of locations with a predilection for the genitourinary tract and gynecologic organs. Despite multiple locoregional recurrences, these tumors are thought to behave in a low-grade malignant manner. Here we report a uterine MEIS1::NCOA2 fusion sarcoma with lung metastasis. The patient was a 47-yr-old woman with a history of abnormal uterine bleeding who was found to have a myometrial mass confirmed by pathology to be uterine sarcoma. The tumor was predominantly composed of monotonous spindle cells with scant cytoplasm, crowded nuclei, and brisk mitotic activity, growing in a fascicular and streaming pattern. The morphologic and immunophenotypic features were nonspecific and a diagnosis of high-grade uterine sarcoma with a differential of leiomyosarcoma versus high-grade endometrial stromal sarcoma was rendered. At the 27-mo follow-up, the patient was found to have a lung metastasis consisting of a monotonous round cell sarcoma. A retrospective RNA-based and DNA-based next-generation sequencing of the primary uterine sarcoma revealed a MEIS1::NCOA2 gene fusion, a c.94G>C/p.D32H mutation in exon 3 of CTNNB1 gene, HMGA2 , and CDK4 gene amplification, and an intermediate/marginal level of MDM2 gene amplification. Polymerase chain reaction-based molecular analysis further demonstrated that the MEIS1::NCOA2 gene fusion and CTNNB1 somatic mutation were also present in the lung metastasis. This case represents the first case of such gynecologic sarcoma with distant (lung) metastasis, and the second metastatic case among all reported MEIS1::NCOA1/2 fusion sarcomas, highlighting the malignant metastatic potential of this emerging entity. Our case also indicates that HMGA2/CDK4/MDM2 region amplification and CTNNB1 somatic mutation might be recurrent genetic events in this rare sarcoma subtype.

We report an exceptional case of an undifferentiated round and spindle cell sarcoma, occurring in the periprostatic region of a 54-year-old male, with a \'high-grade endometrial stromal sarcoma-like\' (HG-ESS) morphology and harboring a ZC3H7B::BCOR gene fusion identified by RNA-based next-generation sequencing. In this report, we describe the striking overlap of morphologic, immunohistochemical and molecular features of this current case and previously reported similar cases with ZC3H7B::BCOR fusion-positive HG-ESS, and discuss the differential diagnosis and possible pathogenesis of this unusual entity.

OBJECTIVE: We report a low-grade endometrial stromal sarcoma (ESS) with a novel CDKN1A-JAZF1 fusion gene arising from abdominal wall endometrioma.
METHODS: A 40-year-old woman presented with a 5.5-cm abdominal wall mass juxtaposed to the postoperative scar of two cesarean sections. Histologically, the tumor exhibited obvious tongue-like protrusions into the surrounding tissue, showed spindle cells with multinodular growth pattern that occasionally rotate around small arteries. Immunohistochemically, the tumor cells were positive for CD10, estrogen receptor (ER), progesterone receptor (PR), negatively stained for smooth muscle actin (SMA), CD117, CyclinD1. In addition, a previously undescribed gene fusion between CDNK1A 5\' end of exon 1(NM_000389.5) and JAZF1 3\' end of exon 5 (NM_175,061,3) was reported in this case.
CONCLUSIONS: This report of ESS suggesting that rapidly growing abdominal wall masses without menstruation-related should be promptly evaluated and treated aggressively. In addition, we have expanded the molecular landscape of low-grade ESS.

Endometrial stromal sarcoma (ESS) is the second most common uterine mesenchymal neoplasm. ESS can arise from extrauterine locations without any uterine involvement and is called extrauterine ESS (EESS). The epidemiological features of EESS are not well-known. Moreover, the factors affecting its outcome have not been systemically studied. The treatment of EESS closely follows that of uterine ESS, comprised of different combinations of surgical management, hormone therapy, chemotherapy, and radiation therapy. However, the effectiveness of different treatment protocols for EESS has not been studied. Here, we have performed a systematic review of all reported cases of EESS in the English literature. We further performed a meta-analysis of the outcome data and investigated how the patients\' age, tumor site, tumor size, and management affect the overall and progression-free survival of the patients. We found that tumor site and mode of treatment significantly affected the overall survival and progression-free survival of the patients. Tumor size significantly affected overall survival but not progression-free survival, while the age at diagnosis did not affect patient outcome. As far as we know, ours is the first systematic study of this rare malignancy with an emphasis on outcome analysis.

BACKGROUND: This study aimed to analyze the clinical and pathological features of extrauterine endometrial stromal sarcoma (EESS) and explore an effective therapeutic regimen to reduce the recurrence rate in low-grade EESS patients.
METHODS: Ten LG-EESS patients who were treated at the Chinese Academy of Medical Sciences Cancer Institute and Hospital from June 1999 to June 2019 were collected and analyzed.
RESULTS: (1) Patient demographics are summarized in manuscript. Preoperative CA125 examination showed that 8 patients had a median level of 49.5 U/L (15.4-168.0 U/L). (2) All ten patients underwent tumor cytoreductive surgery. Five patients underwent optimal tumor resection and achieved an R0 resection. After the initial surgery, 7 patients who had multiple metastasis were treated with adjuvant chemotherapy, 2 patients with vaginal ESS were treated with chemotherapy and radiation therapy, and 6 patients with ER/PR positive received hormone therapy with or without chemotherapy. (2) Most EESS patients had multiple tumors. The omentum was the most commonly affected site, followed by the ovaries. (3) The median follow-up was 94 (range: 27-228) months, and recurrence was observed in 3 patients (n = 10, 30%) who underwent non-optimal surgery and no hormone therapy. The 5-year and 10-year DFS rates were both 70%, as shown in Fig. 2. OS was both 100% at 5 and 10 years.
CONCLUSIONS: As a conclusion, EESS is a rare disease and LG-EESS has a good prognosis. Surgery remains the available treatment for patients. LG-EESS has a risk of late recurrence which requires a long-term follow-up. With a limited sample size, our study shows optimal tumor reductive surgery and adjuvant hormone therapy may significantly reduce the risk of recurrence.