Epithelioid Leiomyosarcoma of the Uterus: Modern Outcome-based Appraisal of Diagnostic Criteria in a Large Institutional Series

MG132 induces cell type‑specific anticancer effects in uterine leiomyosarcoma cell lines

Uterine leiomyosarcoma (Ut‑LMS) is a rare and aggressive malignant tumor with limited therapeutic options. Therefore, exploration of novel treatment strategies is necessary. MG132 is a potent proteasome inhibitor that has shown promising potential in cancer therapy by inducing apoptosis through disruption of protein homeostasis. Despite its promising applications in various cancers, its effects on Ut‑LMS remains largely unexplored. Therefore, the present study investigated the effects of MG132 on Ut‑LMS cell lines (SK‑LMS‑1, SK‑UT‑1 and SK‑UT‑1B) in terms of cytotoxicity, apoptosis induction, cell cycle progression, autophagy and reactive oxygen species (ROS) production. Treatment with MG132 (0‑2 µM for 24 h) induced a dose‑dependent reduction in cell viability across all three cell lines, and the lactate dehydrogenase release assays confirmed membrane damage. Moreover, apoptosis induction was assessed using annexin V and 7‑AAD staining, which revealed dose‑dependent apoptosis in all three cell lines. Western blot analysis revealed increased cleaved poly‑adenosine diphosphate ribose polymerase and caspase‑3 levels, thereby indicating activation of the apoptotic pathway in response to MG132 treatment. MG132 also induced G2/M phase arrest in SK‑LMS‑1 and SK‑UT‑1 cells and altered the expression of cell cycle regulatory proteins, such as p21, p27 and p53. Furthermore, MG132 promoted autophagy in all three cell lines by increasing light chain 3 II levels. ROS levels remained unchanged in SK‑LMS‑1 cells but increased in SK‑UT‑1B and SK‑UT‑1 cells. Furthermore, the ROS scavenger N‑acetylcysteine effectively reduced MG132‑induced apoptosis in SK‑UT‑1 cells. These findings highlight the cytotoxicity of MG132 in Ut‑LMS cells, emphasize its potential as a therapeutic agent for Ut‑LMS, provide insights into its mechanisms of action, and suggest possible strategies for improving treatment efficacy.

Primary Splenic Leiomyosarcoma With Metastasis in a Rhesus Monkey (Macaca mulatta)

Primary mesenchymal tumours of the spleen in non-human primates are exceedingly rare. We report on a 13-year-old female rhesus monkey who had an enlarged liver, spleen and multiple lung masses. Macroscopic, microscopic and immunohistochemical examinations revealed a splenic leiomyosarcoma with widespread metastasis. This is the first report of a splenic leiomyosarcoma in a non-human primate.

Gynecologic Leiomyosarcoma With Epithelioid Features and PGR::NR4A3 Gene Fusion: First Report in the Vulva

Vulval leiomyosarcomas with variant features are rare with limited data available in the literature compared to their uterine counterparts. Gynecologic leiomyosarcoma with nuclear receptor 4A3 (NR4A3) gene fusion is a rare, recently described neoplasm that has been reported mostly in the uterus and rarely in the pelvis. Herein, we report the first case of this entity occurring as a primary vulva tumor in a 46-year-old patient. Histologic examination showed a multi-nodular tumor composed of monomorphic epithelioid, rhabdoid and spindled cells arranged in sheets, cords and microcysts within a richly vascularised, myxoid stroma. On immunohistochemistry, the tumor cells were positive for desmin, smooth muscle actin, h-caldesmon, as well as ER and WT1. Gene fusion analysis revealed the presence of a PGR::NR4A3 gene fusion involving exon 2 of PGR and exon 2 of NR4A3. Local recurrence occurred one year after initial excision. Recognition of this rare subtype of gynecologic leiomyosarcoma in the vulva may help refine the classification of unusual vulvovaginal smooth muscle neoplasms.

Risk Stratification of Uterine Smooth Muscle Tumors: The Role of Morphology, Immunohistochemistry, and Molecular Testing

Uterine smooth muscle neoplasms are a biologically and clinically heterogeneous group of tumors. Morphology is the cornerstone of pathologic diagnosis of these tumors, and most are readily classified as benign or malignant on the basis of routine histologic examination. However, rare subsets-including intravenous leiomyomatosis, benign metastasizing leiomyoma, and disseminated peritoneal leiomyomatosis-have a capacity for extrauterine spread despite benign cytomorphology. A further subset of uterine smooth muscle neoplasms, termed "smooth muscle tumor of uncertain malignant potential (STUMP)," are not readily classified as benign or malignant and carry an intermediate prognosis. STUMP is a protean category, whose precise definition is subject to disagreement among experts. The risk profiles of different STUMP morphotypes remain largely unresolved. Finally, multiple morphology-based systems for risk stratification of uterine leiomyosarcoma have been proposed, though none is widely adopted. Immunohistochemical and molecular prognostic markers for both STUMP and leiomyosarcoma remain in the early phases of adoption in routine diagnostic practice.

Uterine Smooth Muscle Tumors: An Overview

Uterine smooth muscle tumors are a heterogeneous group of mesenchymal neoplasms with multiple histologic variants and distinct biological behaviors. Pathologic classification (benign, uncertain malignant potential, malignant) relies on the evaluation of mitotic index, necrosis, and degree of cytologic atypia, with different thresholds based on each subtype. Immunohistochemistry and other ancillary studies may be necessary to establish the diagnosis in a subset of cases, given the morphologic overlap with other mesenchymal neoplasms, including low-grade and high-grade endometrial stromal tumors, inflammatory myofibroblastic tumors, and PEComa. Recent advances in molecular diagnostics have refined the classification of smooth muscle tumors, but most cases are diagnosed purely on histologic grounds.

The "Other" Uterine Mesenchymal Neoplasms: Recent Developments and Emerging Entities

Uterine mesenchymal neoplasms are a challenging group of tumors that often show overlapping morphologic features and immunohistochemical profiles. The increasing use of molecular testing in these tumors has enabled a better appreciation of their pathobiology, resulting in a wave of emerging neoplasms and improved characterization of ones previously considered exceptionally rare. Identification of specific molecular alterations has permitted targeted therapy options in tumors that were typically unresponsive to conventional therapies, as well as recognition that a subset can have a hereditary basis. This review will discuss the more "common" of the uncommon uterine mesenchymal neoplasms, including inflammatory myofibroblastic tumor, perivascular epithelioid cell tumor, uterine tumor resembling ovarian sex cord tumor, and embryonal rhabdomyosarcoma. This will be followed by an overview of emerging entities, including NTRK -rearranged uterine sarcoma, SMARCA4 -deficient uterine sarcoma, KAT6B/A::KANSL1 fusion uterine sarcoma, and MEIS1::NCOA2/1 fusion sarcoma.

Comprehensive Review of Uterine Leiomyosarcoma: Pathogenesis, Diagnosis, Prognosis, and Targeted Therapy

Uterine leiomyosarcoma (uLMS) is the most common subtype of uterine sarcomas. They have a poor prognosis with high rates of recurrence and metastasis. The five-year survival for uLMS patients is between 25 and 76%, with survival rates approaching 10-15% for patients with metastatic disease at the initial diagnosis. Accumulating evidence suggests that several biological pathways are involved in uLMS pathogenesis. Notably, drugs that block abnormal functions of these pathways remarkably improve survival in uLMS patients. However, due to chemotherapy resistance, there remains a need for novel drugs that can target these pathways effectively. In this review article, we provide an overview of the recent progress in ascertaining the biological functions and regulatory mechanisms in uLMS from the perspective of aberrant biological pathways, including DNA repair, immune checkpoint blockade, protein kinase and intracellular signaling pathways, and the hedgehog pathway. We review the emerging role of epigenetics and epitranscriptome in the pathogenesis of uLMS. In addition, we discuss serum markers, artificial intelligence (AI) combined with machine learning, shear wave elastography, current management and medical treatment options, and ongoing clinical trials for patients with uLMS. Comprehensive, integrated, and deeper insights into the pathobiology and underlying molecular mechanisms of uLMS will help develop novel strategies to treat patients with this aggressive tumor.

Combined Treatment of Uterine Leiomyosarcoma with Gamma Secretase Inhibitor MK-0752 and Chemotherapeutic Agents Decreases Cellular Invasion and Increases Apoptosis

Due to limited effective therapeutics for uterine leiomyosarcoma (uLMS), the impact of the gamma secretase inhibitor (GSI) MK-0752 with common chemotherapeutics was explored in uLMS. MTT assays were performed on two human uLMS cell lines, SK-UT-1B and SK-LMS-1, using MK-0752, docetaxel, doxorubicin, and gemcitabine, individually and in combination, to determine cell viability after treatment. Synergistic combinations were used in transwell invasion assays, cell cycle flow cytometry, proliferation assays, and RNA sequencing. In SK-UT-1B, MK-0752 was synergistic with doxorubicin and gemcitabine plus docetaxel. In SK-LMS-1, MK-0752 was synergistic with all individual agents and with the combination of gemcitabine plus docetaxel. MK-0752, gemcitabine, and docetaxel decreased invasion in SK-UT-1B 2.1-fold* and in SK-LMS-1 1.7-fold*. In SK-LMS-1, invasion decreased 1.2-fold* after treatment with MK-0752 and docetaxel and 2.2-fold* after treatment with MK-0752 and doxorubicin. Cell cycle analysis demonstrated increases in the apoptotic sub-G1 population with MK-0752 alone in SK-UT-1B (1.4-fold*) and SK-LMS-1 (2.7-fold**), along with increases with all combinations in both cell lines. The combination treatments had limited effects on proliferation, while MK-0752 alone decreased proliferation in SK-LMS-1 (0.63-fold**). Both MK-0752 alone and in combination altered gene expression and KEGG pathways. In conclusion, the combinations of MK-0752 with either doxorubicin, docetaxel, or gemcitabine plus docetaxel are potential novel therapeutic approaches for uLMS. (* p < 0.05, ** p < 0.01).

Expanding the Spectrum of NR4A3 Fusion-Positive Gynecologic Leiomyosarcomas

Recurrent gene fusions have been observed in epithelioid and myxoid variants of uterine leiomyosarcoma. PGR::NR4A3 fusions were recently described in a subset of epithelioid leiomyosarcomas exhibiting rhabdoid morphology. In this study, we sought to expand the clinical, morphologic, immunohistochemical, and genetic features of gynecologic leiomyosarcomas harboring NR4A3 rearrangements with PGR and novel fusion partners. We identified 9 gynecologic leiomyosarcomas harboring PGR::NR4A3, CARMN::NR4A3, ACTB::NR4A3, and possible SLCO5A1::NR4A3 fusions by targeted RNA sequencing. Tumors frequently affected premenopausal women, involving the uterine corpus, uterine cervix, or pelvis. All were similarly characterized by lobules of monomorphic epithelioid and/or spindled cells arranged in sheets, cords, trabeculae, and micro- and macrocysts associated with abundant myxoid matrix and hemorrhage, creating labyrinth-like or pulmonary edema-like architecture. Myogenic differentiation with frequent estrogen receptor and progesterone receptor staining and no CD10 expression characterized all tumors. All cases showed high NR4A3 RNA expression levels and NOR1 (NR4A3) nuclear staining similar to salivary gland acinic cell carcinomas and a subset of extraskeletal myxoid chondrosarcomas harboring NR4A3 rearrangements. NOR1 (NR4A3) immunohistochemistry may serve as a useful diagnostic marker of NR4A3 fusion-positive gynecologic leiomyosarcomas.

[Diagnosis of uterine sarcomas and rare uterine mesenchymal tumours with malignant potential. Guidelines of the French Sarcoma Group and Rare Gynaecological Tumours]

The landscape of uterine sarcomas is becoming more complex with the description of new entities associated with recurrent driver molecular alterations. Uterine sarcomas, in analogy with soft tissue sarcomas, are distinguished into complex genomic and simple genomic sarcomas. Leiomyosarcomas and undifferentiated uterine sarcomas belong to complex genomic sarcomas group. Low-grade and high-grade endometrial stromal sarcomas, other rare tumors associated with fusion transcripts (such as NTRK, PDGFB, ALK, RET ROS1) and SMARCA4-deficient uterine sarcoma are considered simple genomic sarcomas. The most common uterine sarcoma are first leiomyosarcoma and secondly endometrial stromal sarcomas. Three different histological subtypes of leiomyosarcoma (fusiform, myxoid, epithelioid) are identified, myxoid and epithelioid leiomyosarcoma being more aggressive than fusiform leiomyosarcoma. The distinction between low-grade and high-grade endometrial stromal sarcoma is primarily morphological and immunohistochemical and the detection of fusion transcripts can help the diagnosis. Uterine PEComa is a rare tumor, which is distinguished into borderline and malignant, according to a risk assessment algorithm. Embryonal rhabdomyosarcoma of the uterine cervix is more common in children but can also occur in adult women. Embryonal rhabdomyosarcoma of the uterine cervix is almost always DICER1 mutated, unlike that of the vagina which is wild-type DICER1, and adenosarcoma which can be DICER1 mutated but with less frequency. Among the emerging entities, sarcomas associated with fusion transcripts involving the NTRK, ALK, PDGFB genes benefit from targeted therapy. The integration of molecular data with histology and clinical data allows better identification of uterine sarcomas in order to better treat them.

PEComa of the Adrenal Gland: A Clinicopathologic Series of 7 Cases

PEComas are a family of mesenchymal neoplasms composed of histologically distinctive perivascular epithelioid cells which demonstrate myomelanocytic differentiation. PEComas of the adrenal gland are very rare and can represent a considerable diagnostic challenge given their morphologic overlap with more common adrenal cortical neoplasms. We present the clinicopathologic features of 7 primary adrenal PEComas. The cohort comprised 5 male and 2 female patients with a median age of 63 years (range: 31 to 71 y). One patient had Birt-Hogg-Dubé syndrome and another had Lynch syndrome; however, none had a history of tuberous sclerosis complex. Histologically, tumors showed nested and/or sheet-like growth and epithelioid cytomorphology with pale-to-eosinophilic granular cytoplasm. Two tumors had an admixed spindle cell component. There was a median of 4 mitoses per 10 HPFs (range: 0 to 8). Necrosis was present in 4 tumors and lymphovascular invasion in 1. Four tumors were classified as malignant. By immunohistochemistry, tumors were positive for HMB-45 (3/7), MITF (3/3), Melan-A (3/7), smooth muscle actin (5/7), desmin (5/7), and caldesmon (1/1). Two tumors were positive for TFE3 (2/4). Inhibin and SF1 were negative in all tumors assessed (0/6). Of 3 patients with available clinical follow-up information, 1 patient developed locally recurrent and metastatic disease (at 18 mo) and was alive with persistent disease at the last follow-up. Two patients had no recurrent or metastatic disease at the last follow-up (60 and 25 mo). Although PEComas of the adrenal gland are rare, pathologists need to be alert to this entity in the differential diagnosis of primary adrenocortical neoplasms. In suspected cases, the judicious use of melanocytic and smooth muscle markers, in addition to TFE3 and markers of adrenocortical differentiation (such as SF1 and inhibin) can assist in diagnosis. As in PEComas arising at other visceral sites, an association with tuberous sclerosis complex seems to be uncommon.

A Clinicopathologic and Molecular Characterization of Uterine Sarcomas Classified as Malignant PEComa

Perivascular epithelioid cell tumors (PEComas) are a distinctive group of mesenchymal neoplasms that demonstrate features of smooth muscle and melanocytic differentiation. Here, we present the clinicopathologic, immunohistochemical, and molecular features of 15 uterine sarcomas diagnosed as malignant PEComa. The median patient age was 56 years (range: 27 to 86 y). The median tumor size was 8.0 cm (range: 5.0 to 14.0 cm). All tumors were classified as malignant based on the presence of mitoses (15/15; 100%), necrosis (15/15; 100%), lymphovascular invasion (8/15; 53%), and high nuclear grade (13/15; 87%). Molecular analysis revealed the mammalian target of rapamycin pathway gene mutations in 7 cases (47%), including mutually exclusive variants in TSC1 (27%) and TSC2 (20%). Recurrent alterations were also identified in TP53 (53%), RB1 (30%), ATRX (33%), and BRCA2 (13%). Tumors with inactivating ATRX mutations all demonstrated loss of ATRX expression by immunohistochemistry. Loss of expression was also observed in 2 tumors without demonstrable ATRX alterations. Clinical follow-up was available for 14 patients (range: 5 to 92 mo; median: 15 mo). Five patients developed local recurrence and 9 developed metastases; 2 patients died of their disease. Our series expands the spectrum of molecular events in tumors diagnosed as malignant PEComa and further highlights the important role of targeted sequencing in tumors with focal melanocytic marker expression.

Molecular-Based Immunohistochemical Algorithm for Uterine Leiomyosarcoma Diagnosis

The morphologic assessment of uterine leiomyosarcoma (LMS) may be challenging, and diagnostic immunohistochemical (IHC) analysis is currently lacking. We evaluated the genomic landscape of 167 uterine LMS by targeted next-generation sequencing (NGS) to identify common genomic alterations. IHC analyses corresponding to these genomic landmarks were applied to a test cohort of 16 uterine LMS, 6 smooth muscle tumors of uncertain malignant potential (STUMP), and 6 leiomyomas with NGS data and a validation cohort of 8 uterine LMS, 12 STUMP, 21 leiomyomas and leiomyoma variants, 7 low-grade endometrial stromal sarcomas, and 2 diagnostically challenging uterine smooth muscle tumors. IHC results were individually interpreted by 3 pathologists blinded to NGS data. Overall, 94% of LMS showed ≥1 genomic alteration involving TP53, RB1, ATRX, PTEN, CDKN2A, or MDM2, with 80% showing alterations in ≥2 of these genes. In the test cohort, an initial panel of p53, Rb, PTEN, and ATRX was applied, followed by a panel of DAXX, MTAP, and MDM2 in cases without abnormalities. Abnormal p53, Rb, PTEN, and ATRX IHC expression was seen in 75%, 88%, 44%, and 38% of LMS, respectively, in the test cohort. Two or more abnormal IHC results among these markers were seen in 81% of LMS. STUMPs demonstrated only 1 IHC abnormality involving these markers. No IHC abnormalities were seen in leiomyomas. In the validation cohort, abnormal p53, Rb, and PTEN IHC results were seen in LMS, whereas rare STUMP or leiomyomas with bizarre nuclei showed IHC abnormalities involving only 1 of the markers. Abnormalities in ≥2 markers were present in both diagnostically challenging smooth muscle tumors, confirming LMS. Concordance was excellent among pathologists in the interpretation of IHC (κ = 0.97) and between IHC and NGS results (κ = 0.941). Uterine LMS exhibit genomic landmark alterations for which IHC surrogates exist, and a diagnostic algorithm involving molecular-based IHC may aid in the evaluation of unusual uterine smooth muscle tumors.

Uterine sarcomas: clinical practice guidelines for diagnosis, treatment, and follow-up, by Spanish group for research on sarcomas (GEIS)

Uterine sarcomas are very infrequent and heterogeneous entities. Due to its rarity, pathological diagnosis, surgical management, and systemic treatment are challenging. Treatment decision process in these tumors should be taken in a multidisciplinary tumor board. Available evidence is low and, in many cases, based on case series or clinical trials in which these tumors have been included with other soft tissue sarcoma. In these guidelines, we have tried to summarize the most relevant evidence in the diagnosis, staging, pathological disparities, surgical management, systemic treatment, and follow-up of uterine sarcomas.

Cytologic features of metastatic epithelioid uterine leiomyosarcoma to the pancreas

Although uterine leiomyosarcoma (ULMS) is a rare disease, it accounts for a significant proportion uterine cancer-related deaths due to frequent metastasis and chemoresistance. The WHO currently recognizes the conventional (spindle), myxoid, and epithelioid variants of ULMS, the latter of which is the rarest, least understood, and cited as clinically more aggressive than the other variants. Descriptions of the histologic features of epithelioid ULMS are extremely limited, and are absent from the cytology literature which has only published descriptions of conventional ULMS or epithelioid variants of other LMS primaries. Therefore, we present a unique case of metastatic epithelioid ULMS to an unusual location, the pancreas, along with its cytologic features on endoscopic ultrasound-guided fine needle aspiration not previously described including pseudoglandular arrangements, scant cytoplasm, and frequent molding.

Uterine sarcomas and rare uterine mesenchymal tumors with malignant potential. Diagnostic guidelines of the French Sarcoma Group and the Rare Gynecological Tumors Group

The landscape of uterine sarcomas is becoming increasingly complex with the description of new entities associated with recurrent molecular alterations. Uterine sarcomas, as well as soft tissue sarcomas, can be distinguished into complex genomic sarcomas and simple genomic sarcomas. Leiomyosarcoma and pleomorphic type undifferentiated uterine sarcoma belong to the first group. Low-grade and high-grade endometrial stromal sarcomas, NTRK, COL1A1::PDGFB, ALK, RET, ROS1 associated sarcomas, and SMARCA4 deficient uterine sarcoma belong to the second group. Leiomyosarcoma is the most common uterine sarcoma followed by endometrial stromal sarcomas. Three different histologic subtypes of leiomyosarcomas are recognized with distinct diagnostic criteria and different clinical outcomes, the myxoid and epithelioid leiomyosarcomas being even more aggressive than the fusiform type. The distinction between low-grade and high-grade endometrial stromal sarcoma is based first on morphology and immunohistochemistry. The detection of fusion transcripts helps in the diagnosis. Definitely recognized as a separate entity, uterine PEComa is a rare tumor whose diagnostic criteria are being recently defined. Uterine PEComa has a specific algorithm stratifying the tumors into uncertain malignant potential and malignant tumors. Embryonal rhabdomyosarcomas of the uterine cervix are not restricted to children but can also be observed in adult women and are almost always DICER1 mutated, unlike embryonal rhabdomyosarcoma of the vagina which are DICER1wild-type, and adenosarcoma which can be DICER1 mutated but with less frequency. As sarcomas associated with fusion transcripts involving the NTRK, ALK, COL1A1::PDGFB genes can benefit from targeted therapy, systematic detection are now relevant especially for patients with high risk of relapse or in recurrent setting. The integration of molecular data with dedicated expert pathology review for histology and clinical data allows better identification of uterine sarcomas in order to better treat them.

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.

Uterine Leiomyosarcoma Masquerading as a Malignant Perivascular Epithelioid Cell Tumor: A Diagnostic Challenge

Uterine sarcomas with myomelanocytic differentiation have been reported to be diagnostically challenging. We report a case of uterine leiomyosarcoma with extensive perivascular epithelioid cell tumor (PEComa)-like areas and extrauterine metastases. The patient was a 49-year-old gravida 3 para 2 Japanese woman with no relevant medical history. She noticed a vaginal mass with bleeding. Imaging examination revealed a uterine tumor and multiple liver and lung metastases. The vaginal tumor (3.5 cm) was resected and diagnosed as a malignant PEComa based on morphology and myomelanocytic marker expression. Clinically used targeted sequencing (FoundationOneCDx™) revealed gene alterations in RB1, TP53, and ATRX but not TSC1/2. Despite administration of an mTOR inhibitor, the tumor size increased, and subsequently, hysterectomy was performed to relieve the symptoms. The uterine tumor was composed of conventional leiomyosarcoma showing RB1 loss, wild-type TP53 staining, and retained ATRX expression, as well as adjacent predominant PEComa-like components with RB1 loss, TP53 overexpression, and ATRX loss, identical to the characteristics of the vaginal tumor. In the uterine tumor, both HMB-45 and MITF were weak to moderately positive for approximately 40% of tumor cells while Melan-A was negative. The tumor was finally diagnosed as leiomyosarcoma with PEComa-like features. This case exemplifies the tumorigenesis of diagnostically challenging tumors with myomelanocytic differentiation and demonstrates the importance of integrating multiple types of information, including genomic profiling, in making a correct diagnosis leading to appropriate treatment.

Epithelioid Leiomyosarcoma of the Uterus and the Diagnostic Challenge in Diagnosing it on Small Biopsy

Epithelioid leiomyosarcoma of the uterus is a rare soft-tissue tumor of the pelvis with <1% cases. It can be asymptomatic or can reach an enormous size, resulting in chronic pelvic pain, postmenopausal bleeding, or may cause bowel and bladder dysfunction. The diagnostic dilemma arises especially when they have epithelioid morphology. This case is being presented because of its rare incidence along with the diagnostic dilemma it presented due to epithelioid morphology which is a very rare presentation, especially challenging on small biopsies. This case also highlights the usefulness of immunohistochemical markers, such as WT1, p53, and p16, which has important diagnostic as well as prognostic values in rare variants of usual tumors. Leiomyosarcoma per se is a highly aggressive tumor, therefore, timely diagnosis and management are advised.

Update on Uterine Mesenchymal Neoplasms

This review focuses on recent advances in epithelioid and myxoid uterine mesenchymal neoplasms, a category of tumors whereby diagnostic criteria have been rapidly evolving due to advances in molecular testing. Pertinent clinicopathological and molecular features are highlighted for perivascular epithelioid cell tumors, uterine tumors resembling ovarian sex cord tumors, BCOR/BCORL1-altered high-grade endometrial stromal sarcomas, and inflammatory myofibroblastic tumors. Novel developments in epithelioid and myxoid leiomyosarcomas are briefly discussed, and differential diagnoses with key diagnostic criteria are provided for morphologic mimickers.