Endometrial stromal sarcoma located in the myometrium with a low-intensity rim on T2-weighted images: report of three cases and literature review

Soft-Tissue Sarcomas of the Genitourinary Tract with Radiologic-Pathologic Correlation

Genitourinary tract soft-tissue sarcomas are rare neoplasms with varied pathologic and clinical features. While some of these tumors may be aggressive high-grade malignancies, others are low grade with a relatively better prognosis. Given that the grade and extent of the disease are important prognostic factors in these tumors, timely diagnosis is crucial. Unfortunately, most imaging features of these malignancies are not pathognomonic, and various histologic subtypes do not manifest with typical classic imaging features. Therefore, reliable differentiation of the various histologic tumor types is not always possible based solely on the radiologic manifestations. Imaging findings need to be considered in the context of clinical history in corroboration with radiologic-pathologic correlation. The authors discuss the specific imaging and pathologic characteristics of various genitourinary tract soft-tissue sarcomas, emphasizing diagnostic difficulties and differential diagnoses. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

A case of low-grade endometrial stromal sarcoma presented as an intramyometrial mass mimicking uterine leiomyoma on MRI

A low-grade endometrial stromal sarcoma (ESS) has a pattern of presenting as an intramyometrial mass and is often misdiagnosed as cellular leiomyoma or degenerative uterine leiomyoma. A low-grade ESS is a malignant tumour that requires total hysterectomy with bilateral salpingo-oophorectomy; while a leiomyoma is a benign tumour and could be acceptable for enucleation. As the treatment strategies differ between a low-grade ESS and leiomyoma, radiologists should be familiar with the characteristic MRI findings of a low-grade ESS. A 51-year-old woman with abnormal uterine bleeding had been observed for 2 years at a previous hospital for a uterine leiomyoma based on MRI findings. A contrast-enhanced MRI demonstrated an intramyometrial mass composed of three components with the hypointense rim on T2-weighted images (T2WI): the first component was a homogeneous solid structure with mild hyperintensity on T2WI with a low apparent diffusion coefficient value; the second component was cystic; the third component was a structure of low signal intensity on T2WI similar to the muscle. Although a degenerative uterine leiomyoma was a differential diagnosis, these MRI findings were suggestive of a low-grade ESS. A total abdominal hysterectomy, bilateral salpingo-oophorectomy, pelvic lymphadenectomy, and partial omentectomy were performed. The pathological diagnosis was a low-grade ESS. In a low-grade ESS, there are three major patterns of MRI findings: one of these patterns is the less popular but clinically important intramyometrial mass pattern, which can be misdiagnosed as a leiomyoma, and this case conformed to this pattern.

Current Concepts in the Imaging of Uterine Sarcomas

Uterine sarcomas are a group of rare uterine tumors comprised of multiple subtypes with different histologic characteristics, prognoses, and imaging appearances. Identification of uterine sarcomas and their differentiation from benign uterine disease on imaging is of critical importance for treatment planning to guide appropriate management and optimize patient outcomes. Herein, we review the spectrum of uterine sarcomas with a focus on the classification of primary sarcoma subtypes and presenting the typical MR imaging appearances.

MR Imaging of uterine sarcomas: a comprehensive review with radiologic-pathologic correlation

The aim of this article is to summarize the MRI features of each sarcoma subtype and to correlate them with its pathological findings. Literature review through PubMed/Medline database to identify relevant articles on uterine sarcomas, with a special emphasis on their MRI findings and pathological features. While several, more generalistic, MRI findings of a uterine tumour should raise suspicion for malignancy (including irregular contour, intra-tumoral necrosis/hemorrhage and low ADC values), some particular features may suggest their specific histological subtype such as the gross lymphovascular invasion associated with endometrial stromal sarcomas, the "bag of worms" appearance of the low-grade endometrial stromal sarcoma and the "lattice-like" aspect of adenosarcomas which results from the mixed composition of solid and multiseptated cystic components. Knowledge of the different histological uterine sarcoma subtypes, their specific MRI features and comprehension of their pathological background allows for a more confident diagnosis and may indicate the correct histological subtype.

Utility of magnetic resonance imaging for differentiating malignant mesenchymal tumors of the uterus from T2-weighted hyperintense leiomyomas

PURPOSE

To generate a new discrimination method to distinguish between malignant mesenchymal tumors of the uterus and T2-weighted hyperintense leiomyoma based on magnetic resonance imaging findings and clinical features.

MATERIALS AND METHODS

Data from 32 tumors of 32 patients with malignant mesenchymal tumors of the uterus and from 34 tumors of 30 patients with T2-weighted hyperintense leiomyoma were analyzed. Clinical parameters, qualitative magnetic resonance imaging features, including computed diffusion-weighted imaging, and quantitative characteristics of magnetic resonance imaging of these two tumor types were compared. Predictive values for malignant mesenchymal tumors of the uterus were calculated using variant discriminant analysis.

RESULTS

The T1 bright area on qualitative assessment and mean apparent diffusion coefficient value on quantitative assessment yielded the most independent magnetic resonance imaging differentiators of malignant mesenchymal tumors of the uterus and T2-weighted hyperintense leiomyoma. The classification accuracy of the variant discriminant analysis based on three selected findings, i.e., a T1 bright area, computed diffusion-weighted imaging with a b-value of 2000s/mm² (cDWI₂₀₀₀), and T2-hypointense bands, was 84.8% (56/66), indicating high accuracy.

CONCLUSIONS

Variant discriminant analysis using the T1 bright area, cDWI₂₀₀₀, and T2-hypointense bands yielded high accuracy for differentiating between malignant mesenchymal tumors of the uterus and T2-weighted hyperintense leiomyoma.

Differentiation of uterine low-grade endometrial stromal sarcoma from rare leiomyoma variants by magnetic resonance imaging

The purpose of this study is to evaluate utility of MRI in differentiation of uterine low-grade endometrial stromal sarcoma (LGESS) from rare leiomyoma variants. This multi-center retrospective study included consecutive 25 patients with uterine LGESS and 42 patients with rare leiomyoma variants who had pretreatment MRI. Two radiologists (R1/R2) independently evaluated MRI features, which were analyzed statistically using Fisher's exact test or Student's t-test. Subsequently, using a five-point Likert scale, the two radiologists evaluated the diagnostic performance of a pre-defined MRI system using features reported as characteristics of LGESS in previous case series: uterine tumor with high signal intensity (SI) on diffusion-weighted images and with either worm-like nodular extension, intra-tumoral low SI bands, or low SI rim on T2-weighted images. Area under the receiver operating characteristic curve (AUC), sensitivity, and specificity of the two readers' Likert scales were analyzed. Intra-tumoral low SI bands (p < 0.001), cystic/necrotic change (p ≤ 0.02), absence of speckled appearance (p < 0.001) on T2-weighted images, and a low apparent diffusion coefficient value (p ≤ 0.02) were significantly associated with LGESS. The pre-defined MRI system showed very good diagnostic performance: AUC 0.86/0.89, sensitivity 0.95/0.95, and specificity 0.67/0.69 for R1/R2. MRI can be useful to differentiate uterine LGESS from rare leiomyoma variants.

Uterine adenomyosis with extensive glandular proliferation: case series of a rare imaging variant

PURPOSE

We aimed to investigate the clinical and magnetic resonance imaging (MRI) characteristics of uterine adenomyosis, in which there is an extensive area of high signal intensity in the myometrium on T2-weighted MRI.

METHODS

This retrospective radiographic study reviewed a case series of six patients (mean age, 36 years) with adenomyosis. These patients were selected because, unlike in classical adenomyosis, T2-weighted images showed a larger area of high signal intensity than that of low signal intensity in the myometrium. The morphology of the myometrial lesions, patterns of contrast enhancement (n=4), intramyometrial hemorrhaging, diffusion restriction (n=5), endometrial lesions, and imaging findings after treatment (n=3) were evaluated on MRI.

RESULTS

The patients' clinical symptoms included vaginal bleeding and severe anemia. Four were administered hormonal therapy, one underwent hysterectomy, and one underwent enucleation. On T2-weighted images, all showed endometrial thickening and a high signal intensity area in the myometrium that was divided up by a mesh of low signal intensity bands, with an appearance reminiscent of a fish caught in a net. Other findings included gradual centripetal enhancement with contrast defects in multicystic areas (4/4), an intramyometrial hemorrhage (1/6), and increased diffusion (5/5). Following hormonal therapy, the uteruses decreased in size and were similar to those of classical adenomyosis on MRI (3/3). The lesions were diagnosed as adenomyosis with a proliferation of adenomyotic glandular tissue and a proliferative endometrial polyp.

CONCLUSION

This case series suggests that there is a subgroup of uterine adenomyosis that shows a characteristic "fish-in-a-net" appearance on T2-weighted images.

MR imaging findings of unusual leiomyoma and malignant uterine myometrial tumors: what the radiologist should know

Uterine sarcomas account for less than 1% of gynecological malignancies and 2-5% of all uterine malignancies. Such sarcomas mainly include leiomyosarcoma (LMS) and endometrial stromal sarcoma (ESS). Additionally, inflammatory myofibroblastic tumor (IMT) and endometrial carcinoma arising in adenomyosis can occur as uterine myometrial tumors. Their differentiation from leiomyoma (LM), particularly degenerated LM and the malignant tumors, is challenging, but preoperative diagnosis is very important for the patient's management. We demonstrate the useful and compulsory findings to differentiate between uterine myometrial malignant tumors and degenerated LM with an unusual appearance.

Low-Grade Endometrial Stromal Sarcoma with a Nodule-in-Nodule Appearance in Preoperative Magnetic Resonance Images

Low-grade endometrial stromal sarcoma (LG-ESS) is a rare malignant disease and demonstrates various patterns in preoperative imaging. Therefore, accurate diagnosis is important. Given its unique form, we report a case of LG-ESS with a nodule-in-nodule appearance on preoperative imaging. A 41-year-old woman was referred to our department for further examination of a 45 mm diameter uterine corpus mass. Preoperative magnetic resonance imaging (MRI) revealed several small nodules within a larger nodule. T2-weighted images showed moderate-to-high signal intensity with focal bands of low signal intensity in the small nodules. The patient underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy. Histopathological findings of the small nodules showed densely concentrated endometrial stromal cells reminiscent of a proliferative phase endometrium with a concentric arrangement of small spiral arteriole-like vessels. The small nodules exhibited an expansile growth pattern and were surrounded by less densely concentrated endometrial stromal cells intermingled with the normal uterine myometrium. LG-ESS with smooth muscle differentiation and sex cord-like elements was partially observed. In summary, LG-ESS demonstrating a unique nodule-in-nodule appearance on preoperative imaging histopathologically comprised tumor cells of varying densities. Our current case suggests that preoperative diagnostic imaging with MRI may be useful.

Utility of diffusion-weighted and contrast-enhanced magnetic resonance imaging in diagnosing and differentiating between high- and low-grade uterine endometrial stromal sarcoma

BACKGROUND

Endometrial stromal sarcoma (ESS) is a rare uterine malignancy that features different prognoses for its high- and low-grade subtypes. We investigated the diagnostic accuracy of magnetic resonance (MR) imaging in diagnosing and differentiating between high- and low-grade ESS.

METHODS

We retrospectively reviewed the preoperative pelvic MR images of consecutive patients who received histologically confirmed diagnoses of high-grade ESS (n = 11) and low-grade ESS (n = 9) and T2-hyperintense leiomyoma (n = 16). Two radiologists independently evaluated imaging features in T1-, T2-, and diffusion-weighted and contrast-enhanced MR images. Statistical analysis included Mann-Whitney tests and Fisher's exact test, with sensitivity, specificity and diagnostic accuracy of imaging features.

RESULTS

High-grade ESS was associated with significantly more extensive necrosis and hemorrhage and distinct feather-like enhancement compared with low-grade ESS (P < .05 for all). The feather-like enhancement pattern yielded a diagnostic accuracy of 95%, sensitivity of 91%, and specificity of 100% in differentiating high-grade from low-grade ESS. This imaging characteristic was significantly superior to the necrosis (80%, P = .033) or hemorrhage (75%, P = .007). Both high- and low-grade ESS demonstrated T2 hypointense bands, marginal nodules, intratumoral nodules, and worm-like intra-myometrial nodules, and their tumor apparent diffusion coefficient (ADC) values were significantly lower than those of T2-hyperintense leiomyomas (P < .001).

CONCLUSIONS

Diffusion-weighted MR imaging is useful in diagnosing ESS against T2-hyperintense leiomyomas, and contrast enhancement aids in further differentiating between high- and low-grade ESS.

Current Status of Magnetic Resonance Imaging in Patients with Malignant Uterine Neoplasms: A Review

In this study, we summarize the clinical role of magnetic resonance imaging (MRI) in the diagnosis of patients with malignant uterine neoplasms, including leiomyosarcoma, endometrial stromal sarcoma, adenosarcoma, uterine carcinosarcoma, and endometrial cancer, with emphasis on the challenges and disadvantages. MRI plays an essential role in patients with uterine malignancy, for the purpose of tumor detection, primary staging, and treatment planning. MRI has advanced in scope beyond the visualization of the many aspects of anatomical structures, including diffusion-weighted imaging, dynamic contrast enhancement-MRI, and magnetic resonance spectroscopy. Emerging technologies coupled with the use of artificial intelligence in MRI are expected to lead to progressive improvement in case management of malignant uterine neoplasms.

Endometrial Stromal Sarcoma of the Uterus: Magnetic Resonance Imaging Findings Including Apparent Diffusion Coefficient Value and Its Correlation With Ki-67 Expression

OBJECTIVE

This study aimed to investigate the conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) features of endometrial stromal sarcoma (ESS) including a preliminary investigation of the correlation between the apparent diffusion coefficient (ADC) value and Ki-67 expression.

METHODS

The clinical and MRI data of 15 patients with ESS confirmed by surgery and pathology were analyzed retrospectively. The conventional MR morphological features, signal intensity on DWI, ADC value (n = 14), and clinicopathological marker Ki-67 (n = 13) were evaluated.

RESULTS

Of 15 patients with ESS, 13 tumors were low-grade ESS (LGESS), and the remaining 2 were high-grade ESS (HGESS); 9 tumors were located in the myometrium, 5 were located in the endometrium and/or cervical canal, and 1 was located in extrauterine. Thirteen (87%) of 15 tumors showed a homo- or heterogeneous isointensity on T1-weighted imaging and a heterogeneous hyperintensity on T2-weighted imaging. The hypointense bands were observed in 11 tumors (73%) on T2-weighted imaging. The degenerations (cystic/necrosis/hemorrhage) were observed in 7 LGESS tumors and 2 HGESS tumors. The DWI hyperintensity was observed in 13 tumors (93%) and isointensity in remaining 1. The mean ADC value of the solid components in 14 ESSs was (1.05 ± 0.20) × 10mm/s. The contrast-enhanced MRI showed an obvious enhancement in 14 tumors (93%) (heterogeneous in 7 LGESSs and 2 HGESSs; homogeneous in 5 LGESSs). The ADC value was inversely correlated with the Ki-67 expression (r = -0.613, P = 0.026).

CONCLUSIONS

Patients with ESS showed some characteristics on conventional MRI and DWI, and there was an inverse correlation between the ADC value and Ki-67 expression.

What MRI features suspect malignant pure mesenchymal uterine tumors rather than uterine leiomyoma with cystic degeneration?

Objective

To retrospectively assess conventional magnetic resonance imaging (MRI) features that differentiate malignant pure mesenchymal uterine tumors (MPMUT); endometrial stromal sarcoma (ESS) and leiomyosarcoma (LMS) from uterine leiomyoma with cystic degeneration (ULCD).

Methods

We retrospectively reviewed magnetic resonance (MR) images of 30 patients with ULCD, 18 with ESS, and 15 with LMS, to assess tumor location, margin, T2 signal intensity (SI), speckled appearance, and peripheral band using univariate and multivariate analyses.

Results

ULCD more frequently showed subserosal location (53.3%), well-defined margin (96.7%), and speckled appearance (90.0%) compared with ESS (0%, 33.3%, and 33.3%, respectively) or LMS (20.0%, 33.3%, and 60.0%, respectively). In quantitative T2 SI comparisons, the T2 SI ratio of the main solid tumor portion to gluteus maximus muscle differed significantly among the three groups, with ULCD showing a lower SI ratio (0.62) compared with ESS (2.44) and LMS (1.13). On multivariate analysis, an ill-defined margin (odds ratio [OR]=44.885; p=0.003) and high T2 SI (OR=4.396; p=0.046) were the significant MR differentiators.

Conclusion

An ill-defined tumor margin and high T2 SI ratio of the main solid tumor-to-gluteus maximus muscle were useful MRI features in the differentiation of MPMUT from ULCD.

Magnetic resonance imaging features of uterine sarcoma and mimickers

Uterine myometrial tumors are predominantly benign conditions that affect one-third of women and represent the main indication for hysterectomy. Preoperative imaging is of utmost importance for characterization and for precise mapping of myometrial tumors to best guide therapeutic strategy. New minimally invasive therapeutic strategies including morcellation, myolysis, uterine artery embolization and image-guided radiofrequency or focused ultrasound ablation have been developed for the treatment of uterine leiomyoma. However, preoperative differentiation between atypical leiomyomas and leiomyosarcomas is critical on imaging as uterine sarcoma requires a specific surgical technique to prevent dissemination. A single, rapidly growing uterine tumor, associated with endometrial thickening and ascites, in post-menopausal women is suspicious of uterine endometrial stromal sarcoma and carcinosarcoma. Suggestive magnetic resonance imaging features have been described, but overlap in imaging appearance between uterine leiomyosarcomas and cellular leiomyomas makes it challenging to ascertain the diagnosis. This review aims to illustrate the imaging features of uterine sarcomas and potential mimickers to make the reader more familiar with this serious condition which needs special consideration.

Uterine sarcomas: clinical presentation and MRI features

Uterine sarcomas are a rare heterogeneous group of tumors of mesenchymal origin, accounting for approximately 8% of uterine malignancies. They comprise leiomyosarcoma, endometrial stromal sarcoma, undifferentiated endometrial sarcoma, and adenosarcoma. Compared with the more common endometrial carcinomas, uterine sarcomas behave more aggressively and are associated with a poorer prognosis. Due to their distinct clinical and biological behavior, the International Federation of Gynecology and Obstetrics introduced a new staging system for uterine sarcomas in 2009, categorizing uterine carcinosarcoma as a variant of endometrial carcinoma, rather than a pure sarcoma. Magnetic resonance imaging (MRI) has a developing role in the assessment of these malignancies. Features such as tumor localization, irregular or nodular margins, necrosis, rapid growth, intense contrast enhancement, and restriction at diffusion-weighted imaging can suggest the diagnosis and help differentiate from more common leiomyomas and endometrial carcinoma. MRI is therefore extremely useful in preoperative detection and staging and, consequently, in determination of appropriate management. This pictorial review aims to discuss the clinical features of uterine sarcomas, as well as their most common appearances and distinct characteristics in MRI.

Ultrasonographic findings of low-grade endometrial stromal sarcoma of the uterus with a focus on cystic degeneration

PURPOSE

The goal of this study was to perform a retrospective analysis of the ultrasonographic findings associated with low-grade endometrial stromal sarcoma.

METHODS

Ten pathologically confirmed cases of low-grade endometrial stromal sarcoma at our institution from January 2007 to April 2014 were retrospectively reviewed. All patients underwent a preoperative transvaginal ultrasound. Two radiologists came to a consensus regarding the location, size, margin, and echogenicity of the tumor, as well as the presence of intratumoral cystic degeneration and its extent and configuration.

RESULTS

Low-grade endometrial stromal sarcoma manifested as an intramural mass protruding into the endometrial cavity (n=6) or as a purely intramural mass (n=4). The maximal diameter of the lesion ranged from 4 to 9.1 cm (mean, 6.2 cm). The imaging features of low-grade endometrial stromal sarcoma were variable: six cases involved predominantly solid masses containing cystic degeneration, one was a predominantly unilocular cystic mass, two were ill-defined infiltrative solid masses, and one was a well-defined solid mass. Among the seven cases with internal cystic degeneration, five patients showed a multiseptated cystic area or a cystic area with multiple small clusters, while a unilocular cystic area within the tumor was found in two patients.

CONCLUSION

Low-grade endometrial stromal sarcoma is associated with variable ultrasonographic findings with regard to the location, margin, and configuration of the lesion. Multiseptated cystic areas and multiple small areas of cystic degeneration are common.

Magnetic resonance and diffusion-weighted imaging in categorization of uterine sarcomas: correlation with pathological findings

OBJECTIVES

We investigated the utility of magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) in the categorization of uterine sarcoma (US) and compared them with pathological findings.

METHODS

The baseline and MRI characteristics were recorded and compared across the subtypes of USs.

RESULTS

There were no differences in the conventional or DWI signals among the four subtypes of US, except in the heterogeneity of T2-weighted imaging. A difference in the mean apparent diffusion coefficient value for USs and uterine fibroids differed significantly (P=.019).

CONCLUSIONS

MRI characteristics showed no specific differences between any subtypes of US.

Current concepts in the imaging of uterine sarcoma

Recent advances in genetics and pathology have improved our understanding of diagnosis and staging of uterine sarcomas. The major types of uterine sarcomas include leiomyosarcoma, low-grade endometrial stromal sarcoma, undifferentiated endometrial sarcoma, adenosarcoma and carcinosarcoma. The distinctive biological behavior and poor overall survival of uterine sarcoma create challenges in the management of these tumors. We herein present a comprehensive review of taxonomy, epidemiology, pathology, imaging findings and natural history of a wide spectrum of uterine sarcomas.

Uterine sarcomas: then and now

OBJECTIVE

The purpose of this article is to provide an updated review of uterine sarcomas. The traditionally described neoplasms are reviewed as well as several recently characterized entities in terms of their imaging and clinical aspects. We attempt to provide a longitudinal imaging overview, from initial presentation to follow-up. Imaging features are also described of response to traditional therapeutic agents and newer targeted agents.

CONCLUSION

A greater understanding of the pathogenesis has improved our ability to image and treat uterine sarcomas, both at initial staging and on follow-up. Targeted therapy is assuming an increasingly important role in the management of these lesions. It is imperative for radiologists to be aware of response characteristics and potential complications of these agents as well as conventional chemotherapeutic agents.

Sarcomas of abdominal organs: computed tomography and magnetic resonance imaging findings

Sarcomas originating from abdominal organs are extremely rare, and literature in which investigators focus on their imaging features is scarce. This article aims to review the computed tomography and magnetic resonance imaging features of these rare tumors and to help in clinical diagnosis. Various sarcomas (eg, angiosarcoma, undifferentiated embryonal sarcoma, leiomyosarcoma, carcinosarcoma, rhabdomyosarcoma) originating, respectively, from different abdominal visceral organs (liver, pancreas, spleen, kidney, adrenal gland, uterus, and prostate gland) are reviewed along with cases we encountered.