FOXO3a deregulation in uterine smooth muscle tumors.

OBJECTIVE: The present study aimed to investigate FOXO3a deregulation in Uterine Smooth Muscle Tumors (USMT) and its potential association with cancer development and prognosis. METHODS: The authors analyzed gene and protein expression profiles of FOXO3a in 56 uterine Leiomyosarcomas (LMS), 119 leiomyomas (comprising conventional and unusual leiomyomas), and 20 Myometrium (MM) samples. The authors used techniques such as Immunohistochemistry (IHC), FISH/CISH, and qRT-PCR for the present analyses. Additionally, the authors conducted an in-silico analysis to understand the interaction network involving FOXO3a and its correlated genes. RESULTS: This investigation revealed distinct expression patterns of the FOXO3a gene and protein, including both normal and phosphorylated forms. Expression levels were notably elevated in LMS, and Unusual Leiomyomas (ULM) compared to conventional Leiomyomas (LM) and Myometrium (MM) samples. This upregulation was significantly associated with metastasis and Overall Survival (OS) in LMS patients. Intriguingly, FOXO3a deregulation did not seem to be influenced by EGF/HER-2 signaling, as there were minimal levels of EGF and VEGF expression detected, and HER-2 and EGFR were negative in the analyzed samples. In the examination of miRNAs, the authors observed upregulation of miR-96-5p and miR-155-5p, which are known negative regulators of FOXO3a, in LMS samples. Conversely, the tumor suppressor miR-let7c-5p was downregulated. CONCLUSIONS: In summary, the outcomes of the present study suggest that the imbalance in FOXO3a within Uterine Smooth Muscle Tumors might arise from both protein phosphorylation and miRNA activity. FOXO3a could emerge as a promising therapeutic target for individuals with Unusual Leiomyomas and Leiomyosarcomas (ULM and LMS), offering novel directions for treatment strategies.

Segregation, immunohistochemical, molecular and functional analyses classify a novel missense variant in fumarate hydratase (FH) as pathogenic.

Hereditary leiomyomatosis and renal cell cancer (HLRCC) is an autosomal dominant cancer predisposition syndrome characterized by cutaneous leiomyomas, uterine leiomyomas, and aggressive renal cancer. Germline variants in the fumarate hydratase (FH) gene predispose to HLRCC. Identifying germline pathogenic FH variants enables lifetime renal cancer screening and genetic testing for family members. In this report, we present a FH missense variant (c.1039T>C (p.S347P)), initially classified as a variant of uncertain significance. Clinical assessment, histopathological findings, molecular genetic studies, and enzymatic activity studies support the re-classification of the FH c.1039T>C variant to "pathogenic" based on ACMG/AMP criteria. Further insights into pathological recognition of FH-deficient renal cancer are discussed and should be recognized. This study has shown how (a) detailed multi-disciplinary analyses of a single variant can reclassify rare missense variants in FH and (b) careful pathological review of renal cancers is obligatory when HLRCC is suspected.

Germline and Somatic Fumarate Hydratase Testing in Atypical Uterine Leiomyomata.

Women with germline pathogenic variants (PV) in the fumarate hydratase (FH) gene develop cutaneous and uterine leiomyomata and have an increased risk of developing aggressive renal cell carcinomas. Many of these women are unaware of their cancer predisposition until an atypical uterine leiomyoma is diagnosed during a myomectomy or hysterectomy, making a streamlined genetic counseling process after a pathology-based atypical uterine leiomyoma diagnosis critical. However, the prevalence of germline pathogenic/likely PVs in FH among atypical uterine leiomyomata cases is unknown. To better understand FH germline PV prevalence and current patterns of genetic counseling and germline genetic testing, we undertook a retrospective review of atypical uterine leiomyomata cases at a single large center. We compared clinical characteristics between the FH PV, FH wild-type (WT), and unknown genetic testing cohorts. Of the 144 cases with atypical uterine leiomyomata with evaluable clinical data, only 49 (34%) had documented genetic test results, and 12 (8.3%) had a germline FH PV. There were 48 IHC-defined FH-deficient cases, of which 41 (85%) had FH testing and nine had a germline FH PV, representing 22% of the tested cohort and 18.8% of the FH-deficient cohort. Germline FH PVs were present in 8.3% of evaluable patients, representing 24.5% of the cohort that completed genetic testing. These data highlight the disconnect between pathology and genetic counseling, and help to refine risk estimates that can be used when counseling patients with atypical uterine leiomyomata. PREVENTION RELEVANCE: Women diagnosed with fumarate hydratase (FH)-deficient uterine leiomyomata are at increased risk of renal cancer. This work suggests a more standardized pathology-genetic counseling referral pathway for these patients, and that research on underlying causes of FH-deficient uterine leiomyomata in the absence of germline FH pathogenic/likely pathogenic variants is needed.

Genomic profile analysis of leiomyomas with bizarre nuclei and fumarate hydratase deficient leiomyomas: Strengths, weaknesses, and limitations of array-CGH interpretation.

A close relationship has been demonstrated between genomic complexity and clinical outcome in uterine smooth muscle tumors. We studied the genomic profiles by array-CGH of 28 fumarate hydratase deficient leiomyomas and 37 leiomyomas with bizarre nuclei (LMBN) from 64 patients. Follow-up was available for 46 patients (from three to 249 months, mean 87.3 months). All patients were alive without evidence of disease. For 51 array-CGH interpretable tumors the mean Genomic Index (GI) was 16.4 (median: 9.8; from 1 to 57.8), significantly lower than the mean GI in LMS (mean GI 51.8, p < 0.001). We described three groups: (1) a group with FH deletion (24/58) with low GI (mean GI: 11 vs. 22,4, p = 0.02), (2) a group with TP53 deletion (17/58) with higher GI (22.4 vs. 11 p = 0.02), and (3) a group without genomic events on FH or TP53 genes (17/58) (mean GI:18.3; from 1 to 57.8). Because none of these tumors recurred and none showed morphological features of LMS we concluded that GI at the cut-off of 10 was not applicable in these subtypes of LM. By integration of all those findings, a GI <10 in LMBN remains a valuable argument for benignity. Conversely, in LMBN a GI >10 or alteration in tumor suppressor genes, should not alone warrant a diagnosis of malignancy. Nine tumors were tested with Nanocind CINSARC® signature and all were classified in low risk of recurrence. We propose, based on our observations, a diagnostic approach of these challenging lesions.

Targeting Galectin 3 illuminates its contributions to the pathology of uterine serous carcinoma.

BACKGROUND: Uterine serous cancer (USC) comprises around 10% of all uterine cancers. However, USC accounts for approximately 40% of uterine cancer deaths, which is attributed to tumor aggressiveness and limited effective treatment. Galectin 3 (Gal3) has been implicated in promoting aggressive features in some malignancies. However, Gal3's role in promoting USC pathology is lacking. METHODS: We explored the relationship between LGALS3 levels and prognosis in USC patients using TCGA database, and examined the association between Gal3 levels in primary USC tumors and clinical-pathological features. CRISPR/Cas9-mediated Gal3-knockout (KO) and GB1107, inhibitor of Gal3, were employed to evaluate Gal3's impact on cell function. RESULTS: TCGA analysis revealed a worse prognosis for USC patients with high LGALS3. Patients with no-to-low Gal3 expression in primary tumors exhibited reduced clinical-pathological tumor progression. Gal3-KO and GB1107 reduced cell proliferation, stemness, adhesion, migration, and or invasion properties of USC lines. Furthermore, Gal3-positive conditioned media (CM) stimulated vascular tubal formation and branching and transition of fibroblast to cancer-associated fibroblast compared to Gal3-negative CM. Xenograft models emphasized the significance of Gal3 loss with fewer and smaller tumors compared to controls. Moreover, GB1107 impeded the growth of USC patient-derived organoids. CONCLUSION: These findings suggest inhibiting Gal3 may benefit USC patients.

Consistency between Primary Uterine Corpus Malignancies and Their Corresponding Patient-Derived Xenograft Models.

Patient-derived xenograft (PDX) models retain the characteristics of tumors and are useful tools for personalized therapy and translational research. In this study, we aimed to establish PDX models for uterine corpus malignancies (UC-PDX) and analyze their similarities. Tissue fragments obtained from 92 patients with uterine corpus malignancies were transplanted subcutaneously into immunodeficient mice. Histological and immunohistochemical analyses were performed to compare tumors of patients with PDX tumors. DNA and RNA sequencing were performed to validate the genetic profile. Furthermore, the RNA in extracellular vesicles (EVs) extracted from primary and PDX tumors was analyzed. Among the 92 cases, 52 UC-PDX models were established, with a success rate of 56.5%. The success rate depended on tumor histology and staging. The pathological and immunohistochemical features of primary and PDX tumors were similar. DNA sequencing revealed similarities in gene mutations between the primary and PDX tumors. RNA sequencing showed similarities in gene expressions between primary and PDX tumors. Furthermore, the RNA profiles of the EVs obtained from primary and PDX tumors were similar. As UC-PDX retained the pathological and immunohistochemical features and gene profiles of primary tumors, they may provide a platform for developing personalized medicine and translational research.

The clinicopathologic and molecular features, and treatment outcome of fumarate hydratase-deficient renal cell carcinoma: a retrospective comparison with type 2 papillary renal cell carcinoma.

BACKGROUND: To compare clinicopathologic, molecular features, and treatment outcome between fumarate hydratase-deficient renal cell carcinoma (FH-dRCC) and type 2 papillary renal cell carcinoma (T2 pRCC). METHODS: Data of T2 pRCC patients and FH-dRCC patients with additional next-generation sequencing information were retrospectively analyzed. The cancer-specific survival (CSS) and disease-free survival (DFS) were primary endpoint. RESULTS: A combination of FH and 2-succino-cysteine (2-SC) increased the rate of negative predictive value of FH-dRCC. Compared with T2 pRCC cases, FH-dRCC cases displayed a greater prevalence in young patients, a higher frequency of radical nephrectomy. Seven FH-dRCC and two T2 pRCC cases received systemic therapy. The VEGF treatment was prescribed most frequently, with an objective response rate (ORR) of 22.2% and a disease control rate (DCR) of 30%. A combined therapy with VEGF and checkpoint inhibitor reported an ORR of 40% and a DCR of 100%. FH-dRCC cases showed a shortened CSS (P = 0.042) and DFS (P < 0.001). The genomic sequencing revealed 9 novel mutations. CONCLUSIONS: Coupled with genetic detection, immunohistochemical biomarkers (FH and 2-SC) can distinguish the aggressive FH-dRCC from T2 pRCC. Future research is awaited to illuminate the association between the novel mutations and the clinical phenotypes of FH-dRCC in the disease progression.

Short tandem repeats genotyping of gestational choriocarcinoma - our experiences.

OBJECTIVE: This short communication demonstrates how short tandem repeat genotyping can identify the origin of gestational choriocarcinoma. MATERIALS AND METHODS: The origin of gestational choriocarcinoma in our three cases was determined using the short tandem repeats genotyping technique, which involved quantitative fluorescent PCR and fragmentation analysis. RESULTS: In Case 1 despite no medical history of molar pregnancy, DNA analysis indicated that the choriocarcinoma originated from a homozygous complete hydatidiform mole. We conclude, that the patient's complete abortion 10 years prior to the choriocarcinoma diagnosis was an undiagnosed complete hydatidiform mole. In Case 2 and Case 3 the clinically presumed origin of choriocarcinoma was confirmed. CONCLUSION: Determining the origin of choriocarcinoma is essential for clinical application, as it affects the FIGO scoring system for gestational trophoblastic neoplasia, which determines the patient's prognosis and treatment approach.

Racial disparity in uterine leiomyoma: new insights of genetic and environmental burden in myometrial cells.

Uterine leiomyoma (LM), also known as uterine fibroids, are common gynecological tumors and can reach a prevalence of 70% among women by the age of 50 years. Notably, the LM burden is much higher in Black women with earlier onset, a greater tumor number, size, and severity compared to White women. Published knowledge shows that there are genetic, environmental, and lifestyle-based risk factors associated with racial disparity for LM. Significant strides have been made on genomic, epigenomic, and transcriptomic data levels in Black and White women to elucidate the underlying pathomolecular reasons of racial disparity in LM development. However, racial disparity of LM remains a major area of concern in gynecological research. This review highlights risk factors of LM and their role in different races. Furthermore, we discuss the genetics and uterine myometrial microenvironment in LM development. Comparative findings revealed that a major racial difference in the disease is linked to myometrial oxidative burden and altered ROS pathways which is relevant to the oxidized guanine in genomic DNA and MED12 mutations that drive the LM genesis. Considering the burden and morbidity of LM, we anticipate that this review on genetic risk and myometrial microenvironment will strengthen understanding and propel the growth of research to address the racial disparity of LM burden.

BRCA 1/2 mutations and risk of uterine cancer: a systematic review and meta-analysis.

PURPOSE: In this study, we aim to investigate the association between BRCA1/2 mutation and uterine cancer incidence. MATERIAL AND METHOD: We systematically searched three databases including PubMed, Scopus, and Google Scholar up to August 2023; and reviewed 23 cohorts and cross-sectional studies to explore the association between BRCA1/2 mutations and uterine cancer incidence. RESULTS: This systematic review comprised a total of 21 cohort studies and 2 cross-sectional studies after the screening process. According to meta-analysis the prevalence of the BRCA1/2 gene in patients with uterine cancer was 0.02 (95%CI = [0.01,0.03], P < 0.01, I2 = 94.82%) CONCLUSIONS: Our meta-analysis investigates a 2% prevalence of BRCA1/2 mutation in patients with uterine cancer. Patients with BRCA1/2 mutations might be more conscious of uterine malignancies.

The Effect of Race/Ethnicity and MED12 Mutation on the Expression of Long Non-Coding RNAs in Uterine Leiomyoma and Myometrium.

The objective of this study was to elucidate the expression of long non-coding RNA (lncRNA) in leiomyomas (Lyo) and paired myometrium (Myo) and explore the impact of race and MED12 mutation. Fold change analysis (Lyo/paired Myo) indicated the expression of 63 lncRNAs was significantly altered in the mutated group but not in the non-mutated Lyo. Additionally, 65 lncRNAs exhibited an over 1.5-fold change in the Black but not the White group. Fifteen differentially expressed lncRNAs identified with next-generation sequencing underwent qRT-PCR confirmation. Compared with Myo, the expression of TPTEP1, PART1, RPS10P7, MSC-AS1, SNHG12, CA3-AS1, LINC00337, LINC00536, LINC01436, LINC01449, LINC02433, and LINC02624 was significantly higher, while the expression of ZEB2-AS1, LINC00957, and LINC01186 was significantly lower. Comparison of normal Myo with diseased Myo showed significant differences in the expression of several lncRNAs. Analysis based on race and Lyo MED12 mutation status indicated a significantly higher expression of RPS10P7, SNHG12, LINC01449, LINC02433, and LINC02624 in Lyo from Black patients. The expression of TPTEP1, PART1, RPS10P7, MSC-AS1, LINC00337, LINC00536, LINC01436, LINC01449, LINC02433, and LINC02624 was higher, while LINC01186 was significantly lower in the MED12-mutated group. These results indicate that Lyo are characterized by aberrant lncRNA expression, which is further impacted by race and Lyo MED12 mutation status.

NPHS2-6 drives cervical squamous cell carcinoma (CSCC) progression via hsa-miR-1323/SMC1B axis to activate PI3K-Akt pathway

Purpose A substantial amount of evidence demonstrates suggests that long non-coding RNAs (lncRNAs) play a key role in the progression of various malignancies, cervical squamous cell carcinoma (CSCC) included. In our study, we deeply investigated the role and molecular mechanism of lncRNA NPHS2-6 in CSCC. Methods The expression level of gene and protein expression were measured by qRT-PCR and western blot. To test the cell proliferation and cell metastasis ability, we carried out the CCK-8 experiment, clone formation assay, transwell assay and wound healing, respectively. The interactivity among NPHS2-6, miR-1323 and SMC1B were co demonstrated using the bioinformatics tool, dual-luciferase reporter system, and RNA pulldown assay. The subcutaneous tumor model of nude mice was established to verify the results of previous studies at the in vivo. NPHS2-6 was upregulated in CSCC tissues and cells. Results NPHS2-6 deficiency significantly inhibited CSCC cell growth and EMT in vitro. In addition, NPHS2-6 deficiency also inhibited the growth of CSCC xenograft tumors in mice in vivo. Importantly, NPHS2-6 was a competing endogenous RNA (ceRNA) to increases SMC1B levels by binding to miR-1323, leading to activate the PI3K/Akt pathway, thereby exacerbating tumorigenesis of CSCC. Conclusions In conclusion, NPHS2-6/miR-1323/SMC1B/PI3K/Akt signaling accelerates the progression of CSCC, providing a new direction for the treatment strategy of CSCC (AU)

MMP14 expression and collagen remodelling support uterine leiomyosarcoma aggressiveness.

Fibrillar collagen deposition, stiffness and downstream signalling support the development of leiomyomas (LMs), common benign mesenchymal tumours of the uterus, and are associated with aggressiveness in multiple carcinomas. Compared with epithelial carcinomas, however, the impact of fibrillar collagens on malignant mesenchymal tumours, including uterine leiomyosarcoma (uLMS), remains elusive. In this study, we analyse the network morphology and density of fibrillar collagens combined with the gene expression within uLMS, LM and normal myometrium (MM). We find that, in contrast to LM, uLMS tumours present low collagen density and increased expression of collagen-remodelling genes, features associated with tumour aggressiveness. Using collagen-based 3D matrices, we show that matrix metalloproteinase-14 (MMP14), a central protein with collagen-remodelling functions that is particularly overexpressed in uLMS, supports uLMS cell proliferation. In addition, we find that, unlike MM and LM cells, uLMS proliferation and migration are less sensitive to changes in collagen substrate stiffness. We demonstrate that uLMS cell growth in low-stiffness substrates is sustained by an enhanced basal yes-associated protein 1 (YAP) activity. Altogether, our results indicate that uLMS cells acquire increased collagen remodelling capabilities and are adapted to grow and migrate in low collagen and soft microenvironments. These results further suggest that matrix remodelling and YAP are potential therapeutic targets for this deadly disease.

Establishment of Noninvasive Prediction Models for the Diagnosis of Uterine Leiomyoma Subtypes.

OBJECTIVE: To establish prediction models for the diagnosis of the subtypes of uterine leiomyomas by machine learning using magnetic resonance imaging (MRI) data. METHODS: This is a prospective observational study. Ninety uterine leiomyoma samples were obtained from 51 patients who underwent surgery for uterine leiomyomas. Seventy-one samples (49 mediator complex subunit 12 [ MED12 ] mutation-positive and 22 MED12 mutation-negative leiomyomas) were assigned to the primary data set to establish prediction models. Nineteen samples (13 MED12 mutation-positive and 6 MED12 mutation-negative leiomyomas) were assigned to the unknown testing data set to validate the prediction model utility. The tumor signal intensity was quantified by seven MRI sequences (T2-weighted imaging, apparent diffusion coefficient, magnetic resonance elastography, T1 mapping, magnetization transfer contrast, T2* blood oxygenation level dependent, and arterial spin labeling) that can estimate the collagen and water contents of uterine leiomyomas. After surgery, the MED12 mutations were genotyped. These results were used to establish prediction models based on machine learning by applying support vector classification and logistic regression for the diagnosis of uterine leiomyoma subtypes. The performance of the prediction models was evaluated by cross-validation within the primary data set and then finally evaluated by external validation using the unknown testing data set. RESULTS: The signal intensities of five MRI sequences (T2-weighted imaging, apparent diffusion coefficient, T1 mapping, magnetization transfer contrast, and T2* blood oxygenation level dependent) differed significantly between the subtypes. In cross-validation within the primary data set, both machine learning models (support vector classification and logistic regression) based on the five MRI sequences were highly predictive of the subtypes (area under the curve [AUC] 0.974 and 0.988, respectively). External validation with the unknown testing data set confirmed that both models were able to predict the subtypes for all samples (AUC 1.000, 100.0% accuracy). Our prediction models with T2-weighted imaging alone also showed high accuracy to discriminate the uterine leiomyoma subtypes. CONCLUSION: We established noninvasive prediction models for the diagnosis of the subtypes of uterine leiomyomas by machine learning using MRI data.

Uterine Leiomyosarcoma With Osteoclast-like Giant Cells: Report of 2 Cases and Review of Literature.

Leiomyosarcoma (LMS) with osteoclast-like giant cells (OLGCs) is a rare entity with only 18 reported cases thus far. It is not known whether these OLGCs are a reactive or malignant component of LMS. Herein we describe the clinical, histologic, and molecular characteristics of 2 cases of LMS with OLGCs and perform a brief literature review. In 2 of our cases, the OLGCs, marked with CD68, had a low proliferation index with Ki67 and did not show diffuse positivity for smooth muscle markers by immunohistochemistry. By next-generation sequencing, one case harbored a clinically significant TP53 mutation, which has been reported in a significant subset of conventional LMSs. In this case, based on immunohistochemistry, OLGCs showed different molecular alterations as compared with LMS. Although we did not show a distinct immunophenotype or molecular profile for LMS with OLGCs, this study provides additional data on this rare entity.

The Mediator Complex Subunit 12 (MED-12) Gene and Uterine Fibroids: a Systematic Review.

Uterine leiomyomas are the most common tumor of reproductive-age women worldwide. Although benign, uterine fibroids cause significant morbidity and adversely impact the quality of life for affected women. Somatic mutations in the exon 2 of the mediator complex subunit 12 (MED-12) gene represent the most common single gene mutation associated with uterine leiomyomas. The objective of this review was to evaluate the current role of MED-12 mutation in the pathophysiology of uterine fibroids, to assess the prevalence of MED-12 mutation among different populations, and to identify the most common subtypes of MED-12 mutations found in uterine fibroids. A comprehensive search was conducted using Pubmed, Embase, Scopus, and the Web of Science. English-language publications that evaluated MED-12 mutation and uterine fibroids in humans, whether experimental or clinical, were considered. We identified 380 studies, of which 23 were included, comprising 1353 patients and 1872 fibroid tumors. Of the total number of tumors analyzed, 1045 (55.8%) harbored a MED-12 mutation. Among the 23 studies included, the frequency of MED-12 mutation varied from 31.1 to 80% in fibroid samples. The most common type of MED-12 mutation was a heterozygous missense mutation affecting codon 44 of exon 2, specifically the nucleotide 131. Studies reported that MED-12 mutation acts by increasing levels of AKT and disrupting the cyclin C-CDK8/19 kinase activity. The overall average prevalence of MED-12 mutation in uterine fibroids was found to be 55.8% across the global population, though the frequency varied greatly among different countries.

Fumarate Hydratase-Deficient Leiomyoma of the Uterine Corpus: Comparative Morphologic Analysis of Protein-Deficient Tumors With and Without Pathogenic Germline Fumarate Hydratase Gene Mutations.

Deficiency of fumarate hydratase (FH) protein expression in uterine corpus leiomyomas may be attributable to either germline or somatic mutations of the FH gene, the former being definitional for the hereditary leiomyomatosis and renal cell cancer syndrome. The authors assess whether, using previously reported FH-associated morphologic features, FH protein-deficient uterine corpus leiomyomas associated with a pathogenic germline mutations of the FH gene (group 1) are distinguishable from FH protein-deficient uterine corpus leiomyomas without such mutations (and whose FH protein loss is presumed to be attributable to somatic/epigenetic inactivation or other unknown phenomena: group 2). Groups 1 and 2 were compared regarding a variety of clinicopathologic features, including 7 core "FH-associated" tumoral morphologic features: staghorn vasculature; alveolar-type edema; bizarre nuclei; chain-like tumor nuclei; hyaline cytoplasmic globules; prominent nucleoli, intranuclear inclusions, and perinucleolar halos; and prominent eosinophilic/fibrillary cytoplasm. Among 2418 patients diagnosed with uterine corpus leiomyoma during the study period, FH-associated morphologic features were reported in 1.5% (37 patients), and FH immunohistochemistry was performed in 29 (1.19%). Fourteen (48.27%) of the 29 patients showed FH protein deficiency by immunohistochemistry. Twelve patients underwent germline testing, of which 8 (66.7%) were classified as group 1 and 4 (33.3%) as group 2. FH protein-deficient tumors were larger (10.44 vs 4.08 cm, P = 0.01) and associated with younger patients (42.05 vs 47.97, P = 0.004) than 370 randomly selected uterine leiomyoma controls. Groups 1 and 2 showed no significant differences in patient age and tumor size. In group 1 tumors, the FH-associated morphologic features were generally present diffusely; all group 1 tumors displayed ≥5 FH-associated features, whereas all group 2 tumors displayed <5 FH-associated features (means 6.5 ± 0.53 vs 3.5 ± 1.00, P < 0.001). Notably, eosinophilic/fibrillary cytoplasm and alveolar-type edema were each significantly more prevalent in group 1 tumors than group 2 tumors (P = 0.018 for both). No single morphologic feature was found to be completely sensitive and specific in making the distinction between group 1 and 2 tumors. Our findings suggest that groups 1 and 2 are unlikely to be morphologically distinguishable by individual morphologic features. Whether there is a combination of features that can reliably make this distinction is unclear and will require additional studies with larger cohorts.