A case of c-kit positive high-grade stromal endometrial sarcoma responding to Imatinib Mesylate

Uterine Mesenchymal Tumors: Updates on Pathology, Molecular Landscape, and Therapeutics

Background: Mesenchymal uterine tumors are a diverse group of neoplasms with varying biological potential. Many of these neoplasms can have overlapping morphologic similarities, which, in some instances, render their diagnosis and categorization thorough histomorphologic examination inconclusive. In the last decade, an exponential amount of molecular data aiming to more accurately characterize and, consequently, treat these tumors have accumulated. Objective: The goal of this narrative review is to provide a pathologic review, a genetic update, and to know the new therapeutic avenues of primary uterine mesenchymal neoplasms.

Endometrial stromal tumors of the uterus: Epidemiology, pathological and biological features, treatment options and clinical outcomes

Endometrial stromal tumors (EST) are uterine mesenchymal tumors, which histologically resemble endometrial stroma of the functioning endometrium. The majority of EST are malignant tumors classified as low-grade endometrial stromal sarcoma (LG-ESS), high-grade endometrial stromal sarcoma (HG-ESS), and undifferentiated uterine sarcoma (UUS). Overall, ESTs are rare malignancies, with an annual incidence of approximately 0.30 per 100'000 women, mainly affecting peri- or postmenopausal women. The most common genetic alteration identified in LG-ESS is the JAZF1-SUZ12 rearrangement, while t(10;17)(q23,p13) translocation and BCOR gene abnormalities characterize two major subtypes of HG-ESS. The absence of specific genetic abnormalities is the actual hallmark of UUS. Unlike HG-ESSs, LG-ESSs usually express estrogen and progesterone receptors. Total hysterectomy without morcellation and bilateral salpingo-oophorectomy (BSO) is the first-line treatment of early-stage LG-ESS. Ovarian preservation, fertility-sparing treatment, and adjuvant hormonal therapy ± radiotherapy may be an option in selected cases. In advanced or recurrent LG-ESS, surgical cytoreduction followed by hormonal treatment, or vice versa, are acceptable treatments. The standard treatment for apparently early-stage HG-ESS and UUS is total hysterectomy without morcellation with BSO. Ovarian preservation and adjuvant chemotherapy ± radiotherapy may be an option. In advanced or recurrent HG-ESS, surgical cytoreduction and neoadjuvant or adjuvant chemotherapy can be considered. Alternative treatments, including biological agents and immunotherapy, are under investigation. LG-ESSs are indolent tumor with a 5-year overall survival (OS) of 80-100% and present as stage I-II at diagnosis in two third of patients. HG-ESSs carry a poor prognosis, with a median OS ranging from 11 to 24 months, and 70% of patients are in stage III-IV at presentation. UUS median OS ranges from 12 to 23 months and, at diagnosis, 70% of patients are in stage III-IV. The aim of this review is to assess the clinical, pathological, and biological features and the therapeutic options for malignant ESTs.

Novel Therapeutics in the Treatment of Uterine Sarcoma

Uterine sarcomas reflect the diversity of sarcoma as a whole. The most common histologies include leiomyosarcoma, high- and low-grade endometrial stromal sarcoma, and adenosarcoma. These are clinically and biologically heterogeneous diseases that are challenging to treat in the advanced setting. Recent advances in our understanding of the cancer biology of uterine sarcomas has improved diagnostic evaluation and therapeutic management. Promising approaches for patients with advanced uterine leiomyosarcoma include targeting DNA damage repair pathways and depleting immunosuppressive macrophage populations. A subset of endometrial stromal sarcomas harbor potentially actionable alterations in the Wnt, cyclin D-CDK4/6-Rb, and MDM2-p53 pathways. There remains an urgent need to translate molecular findings into prospective clinical trials of novel agents for patients with these diseases; progress will depend on academic collaborations and enrollment of patients with uterine sarcoma in biomarker-driven basket studies.

LG-ESSs and HG-ESSs: underlying molecular alterations and potential therapeutic strategies

Endometrial stromal tumors (ESTs) include endometrial stromal nodule (ESN), low-grade endometrial stromal sarcoma (LG-ESS), high-grade endometrial stromal sarcoma (HG-ESS), and undifferentiated uterine sarcoma (UUS). Since these are rare tumor types, there is an unmet clinical need for the systematic therapy of advanced LG-ESS or HG-ESS. Cytogenetic and molecular advances in ESTs have shown that multiple recurrent gene fusions are present in a large proportion of LG-ESSs, and HG-ESSs are identified by the tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein epsilon (YWHAE)-family with sequence similarity 22 (FAM22) fusion. Recently, a group of ESSs harboring both zinc finger CCCH domain-containing protein 7B (ZC3H7B)-B-cell lymphoma 6 corepressor(BCOR) fusion and internal tandem duplication (ITD) of the BCOR gene have been provisionally classified as HG-ESSs. In this review, we firstly describe current knowledge about the molecular characteristics of recurrent aberrant proteins and their roles in the tumorigenesis of LG-ESSs and HG-ESSs. Next, we summarize the possibly shared signal pathways in the tumorigenesis of LG-ESSs and HG-ESSs, and list potentially actionable targets. Finally, based on the above discussion, we propose a few promising therapeutic strategies for LG-ESSs and HG-ESSs with recurrent gene alterations.

Utility of YWHAE fluorescent in-situ hybridisation in mesenchymal tumors of uterus- An initial experience from tertiary oncology centre in India

Background

Endometrial stromal sarcoma (ESS) is a common uterine mesenchymal malignancy. According to World Health Organisation (WHO) 2014 classification, ESSs are further subdivided into low-grade ESS (LGESS) and high-grade ESS (HGESS). HGESS is defined by the presence of YWHAE gene rearrangement and has a poorer prognosis compared to LGESS.

METHODS

Twenty-four cases comprising of 16 endometrial stromal sarcoma and 8 lesions mimicking ESS were retrieved from the archives of the Department of Pathology and subjected to fluorescent in situ hybridization (FISH) analysis for YWHAE gene rearrangement. Immunohistochemistry for CD10, ER, PR, Cyclin D1, SMA, H-Caldesmon, Desmin, Ki-67, and Pan Cytokeratin was performed.

RESULTS

Two cases with histological features similar to HGESS were positive for YWHAE gene rearrangement while 1 was indeterminate. No cases of LGESS and histological mimics of ESS were positive for this rearrangement.

CONCLUSIONS

HGESSs are defined by the presence of YWHAE rearrangement. These tumors present at higher stage and have poorer prognosis. They may not respond to hormonal therapy and may be treated with chemotherapy. Cyclin D1 though not specific remains a sensitive tool to triage endometrial stromal sarcomas for this FISH study.

A remarkable response to pazopanib, despite recurrent liver toxicity, in a patient with a high grade endometrial stromal sarcoma, a case report

Background

Pazopanib is an oral tyrosine kinase inhibitor registered for metastatic renal cell carcinoma and soft tissue sarcoma. Liver toxicity is a common side effect for this class of agents. The current opinion is that in case of severe liver toxicity pazopanib should be interrupted and restarted at a lower dose after returning to Common Terminology Criteria for Adverse Events (CTCAE) grade 1. After recurrence of liver toxicity at the lower dose it is advised to permanently stop pazopanib. We describe a patient with an YWHAE-FAM22 translocated endometrial stromal sarcoma with a remarkable response to pazopanib despite recurrent liver toxicity.

Case Presentation

A 40 year old woman was diagnosed with metastatic YWHAE-FAM22 translocated endometrial stromal sarcoma. She was treated successively with doxorubicin, megestrol acetate and anastrozole, before pazopanib was initiated. Several dose interruptions and reductions were necessary due to liver toxicity, but nevertheless she had a good partial response. Seven months after the start, pazopanib was permanently stopped because of a bilateral pneumothorax. Nine months later it was reinitiated because of progression and was continued for another 8 months until final disease progression.

Conclusion

In contrast to the current summary of product characteristics of pazopanib, the drug was successfully continued despite recurrent liver toxicity, and no further liver function deterioration was found. This case suggests that further dose reductions are good practice when liver toxicity limits treatment in responding patients.

Secondly, this patient with rare YWHAE-FAM22 translocated endometrial stromal sarcoma showed a remarkable response to VEGFR/KIT inhibitor pazopanib. Recently, it was reported that this specific subtype of endometrial stromal sarcoma overexpresses CD117, but has no KIT mutations.

This case illustrates that (a) pazopanib can be continued in patients with recurrent liver toxicity after dose reductions under strict surveillance and that (b) pazopanib shows good efficacy in YWHAE-FAM22 translocated endometrial stromal sarcoma.

YWHAE-rearranged high-grade endometrial stromal sarcoma: Two-center case series and response to chemotherapy

OBJECTIVES

YWHAE-rearranged high-grade endometrial stromal sarcoma (HG-ESS) is a rare, recently defined uterine sarcoma harboring t(10;17)(q22;p13) resulting in YWHAE-NUTM2A/B fusion. Chemotherapy sensitivity of metastatic YWHAE-rearranged HG-ESS is unknown. We reviewed the response to chemotherapy in women with YWHAE-rearranged HG-ESS to provide guidance for clinical management.

METHODS

We retrospectively identified patients diagnosed with YWHAE-rearranged HG-ESS who received treatment for metastatic disease at our institutions. Cytogenetics or fluorescence in situ hybridization were performed in all cases to confirm rearrangement and, in conjunction with histopathology, a diagnosis of YWHAE-rearranged HG-ESS. Patient demographics, tumor histology, surgical procedures, radiation therapy, chemotherapy and treatment responses were collected.

RESULTS

Seven patients were identified with YWHAE-rearranged HG-ESS and met criteria for inclusion in this study. The median age at diagnosis was 45 (range 42-47). All patients had undergone hysterectomy with bilateral salpingo-oophorectomy. FIGO stage at diagnosis was IVB in four patients and a single patient each at stage IIIB, II or I. Median follow-up for the cohort was 27months (range 6-123). Six patients received anthracycline-based chemotherapy, with two of six achieving a complete radiologic response. One patient received gemcitabine and docetaxel, resulting in a partial response. For three patients who died from metastatic disease, survival from initial diagnosis was 33, 100 and 123months.

CONCLUSIONS

For metastatic YWHAE-rearranged HG-ESS, prolonged disease control following diagnosis was seen, with notable responses to anthracycline-based therapy. This emphasizes the need for appropriate molecular testing of uterine mesenchymal malignancies and suggests that chemotherapy is an effective treatment option for metastatic YWHAE-rearranged HG-ESS.

Potential Therapeutic Targets in Uterine Sarcomas

Uterine sarcomas are rare tumors accounting for 3,4% of all uterine cancers. Even after radical hysterectomy, most patients relapse or present with distant metastases. The very limited clinical benefit of adjuvant cytotoxic treatments is reflected by high mortality rates, emphasizing the need for new treatment strategies. This review summarizes rising potential targets in four distinct subtypes of uterine sarcomas: leiomyosarcoma, low-grade and high-grade endometrial stromal sarcoma, and undifferentiated uterine sarcoma. Based on clinical reports, promising approaches for uterine leiomyosarcoma patients include inhibition of VEGF and mTOR signaling, preferably in combination with other targeted or cytotoxic compounds. Currently, the only targeted therapy approved in leiomyosarcoma patients is pazopanib, a multitargeted inhibitor blocking VEGFR, PDGFR, FGFR, and c-KIT. Additionally, preclinical evidence suggests effect of the inhibition of histone deacetylases, tyrosine kinase receptors, and the mitotic checkpoint protein aurora kinase A. In low-grade endometrial stromal sarcomas, antihormonal therapies including aromatase inhibitors and progestins have proven activity. Other potential targets are PDGFR, VEGFR, and histone deacetylases. In high-grade ESS that carry the YWHAE/FAM22A/B fusion gene, the generated 14-3-3 oncoprotein is a putative target, next to c-KIT and the Wnt pathway. The observation of heterogeneity within uterine sarcoma subtypes warrants a personalized treatment approach.

Frequent expression of KIT in endometrial stromal sarcoma with YWHAE genetic rearrangement

Endometrial stromal sarcomas with the YWHAE-NUTM2A/B genetic fusion characteristically contain high-grade round to epithelioid cell component that is strongly and diffusely cyclin D1-positive and it may or may not show an associated low-grade fibroblastic/myxoid cell component. They are clinically more aggressive than endometrial stromal sarcomas with the JAZF1-SUZ12 genetic fusion and frequently demonstrate extrauterine extension at initial clinical presentation. In this setting, the tumor may be misdiagnosed as gastrointestinal stromal tumor. This study examines the expression of KIT and ANO1 in 14 YWHAE-NUTM2A/B tumors by immunohistochemistry. Staining localization was determined as membranous and/or cytoplasmic, and the staining intensity was assessed (negative, weak, moderate and strong). Of the 14 tumors, 6 contained only a high-grade round cell component, 2 only a low-grade fibroblastic component and 6 had both components in the slides evaluated. The high-grade round cell component displayed moderate to strong membranous/cytoplasmic KIT staining in all tumors (12 of 12). The low-grade fibroblastic cell component showed only weak cytoplasmic KIT staining in 3 of 8 tumors. In contrast, ANO1 was negative in all 14 neoplasms, irrespective of the component evaluated. Sanger sequencing analysis (exons 9, 11, 13 and 17) and Ampliseq Cancer Panel mutation screen (Ion Torrent) demonstrated no KIT mutations in three KIT-positive YWHAE-NUTM2A/B tumors. This study shows that the high-grade round cell component of YWHAE-NUTM2A/B endometrial stromal sarcoma consistently expresses KIT but lacks KIT hotspot mutations. KIT expression may represent a potential diagnostic pitfall in the evaluation of YWHAE-NUTM2A/B endometrial stromal sarcoma presenting with pelvic/abdominal mass, particularly in situations where its uterine origin is not definitive, and thus a panel of antibodies that includes ANO1 and cyclin D1 is necessary.

Tyrosine kinase receptor status in endometrial stromal sarcoma: an immunohistochemical and genetic-molecular analysis

Endometrial stromal sarcomas (ESS) are rare uterine malignant mesenchymal neoplasms, which are currently treated by surgery, as effective adjuvant therapies have not yet been established. Tyrosine kinase inhibitors have rarely been applied in ESS therapy, with few reports describing imatinib responsivity. The aim of this study was to analyze the status of different tyrosine kinase receptors in an ESS series, in order to evaluate their potential role as molecular targets. Immunohistochemistry was performed for EGFR, c-KIT, PDGFR-α, PDGFR-β, and ABL on 28 ESS. EGFR, PDGFR-α, and PDGFR-β gene expression was investigated by real-time polymerase chain reaction (qRT-PCR) on selected cases. "Hot-spot" mutations were screened for on EGFR, c-KIT, PDGFR-α, and PDGFR-β genes, by sequencing. All analysis was executed from formalin-fixed, paraffin-embedded specimens. Immunohistochemical overexpression of 2 or more tyrosine kinase receptors was observed in 18 of 28 tumors (64%), whereas only 5 tumors were consistently negative. Gene expression profiles were concordant with immunohistochemical overexpression in only 1 tumor, which displayed both high mRNA levels and specific immunoreactivity for PDGFR-α, and PDGFR-β. No activating mutations were found on the tumors included in the study. This study confirms that TKRs expression is frequently observed in ESS. Considering that the responsiveness to tyrosine kinase inhibitors is known to be related to the presence of specific activating mutations or gene over-expression, which are not detectable in ESS, TKRs immunohistochemical over-expression alone should not be considered as a reliable marker for targeted therapies in ESS. Specific post-translational abnormalities, responsible for activation of TKRs, should be further investigated.

Endometrial stromal tumors: immunohistochemical and molecular analysis of potential targets of tyrosine kinase inhibitors

BACKGROUND

The systemic treatment of malignant endometrial stromal tumors (EST) is not well established. A few reports describe objective responses to imatinib, which suggest a novel therapeutic strategy for these tumors. Due to these facts, we aimed to perform a retrospective analysis of possible molecular targets of tyrosine kinase inhibitors (TKI) in EST: KIT, PDGFRA and EGFR.

METHODS

52 endometrial stromal sarcomas and 13 undifferentiated endometrial sarcomas were examined and reviewed. Mutational analysis were performed for exons 9, 11, 13, and 17 of the KIT gene, exons 12 and 18 of the PDGFRA gene and exons 18, 19, 20 and 21 of the EGFR gene. The incidence and distribution of the KIT, PDGFRA, and EGFR expression were examined by immunohistochemistry, and EGFR amplification was assessed by fluorescence in situ hybridization.

RESULTS

No mutations in KIT, PDGFRA and EGFR genes were detected. Overexpression of KIT, PDGFRA, EGFR, was detected in 2 (3%), 23 (35.4%), 7 (10.8%) cases respectively, whereas amplification of EGFR gene was not found.

CONCLUSIONS

Absence of significant expression, amplification and activating mutations on these tyrosine kinase receptors suggest that it is unlikely that EST can benefit from therapies such as TKI on the systemic setting.

Immunohistochemical Analysis for Therapeutic Targets and Prognostic Markers in Low-Grade Endometrial Stromal Sarcoma

Objective

To investigate potential therapeutic targets and prognostic markers for low-grade endometrial stromal sarcoma (LGESS).

Materials and Methods

Thirty-nine patients with LGESS were included in this study. Using tissue microarrays, the immunohistochemical expression levels of 5 therapeutic targets (epidermal growth factor receptor, human epidermal growth factor 2, vascular endothelial growth factor receptor, platelet-derived growth factor receptor [PDGFR], and c-kit) and 3 proteins involved in cell proliferation (p16, p53, and ki67) were investigated. The associations between these targets, markers, other clinicopathological factors, disease-free survival (DFS), and overall survival (OS) were analyzed.

Results

Epidermal growth factor receptor and human epidermal growth factor 2 were not expressed in these 39 patients. Vascular endothelial growth factor receptor, PDGFR, c-kit, p16, p53, and ki67 were expressed in 10 (25.6%), 28 (71.8%), 32 (82.1%), 18 (46.2%), 4 (10.3%), and 21 (53.8%) patients, respectively. The expression of each marker was not significantly associated with other clinicopathological factors. On multivariate analysis, p53 and ki67 were associated with significantly poorer DFS and OS. The 5-year DFS rates were 88%, 46%, and 0% for the p53(−)/ki67(−) group (n = 18), p53(−)/ki67(+) group (n = 17), and p53(+)/ki67(+) group (n = 4) (P = 0.002), respectively; the 5-year OS rates were 100%, 71%, and 0%, respectively (P < 0.001). The time to recurrence was longer (P = 0.123), and more patients had distant recurrence in the p53(+)/ki67(+) group (P = 0.063).

Conclusions

In patients with LGESS, c-kit and PDGFR were expressed in higher portions of patients, suggesting that imatinib mesylate should be investigated as a potential targeting agent. Both p53 and ki67 demonstrated strong prognostic implications, suggesting that further evaluation using these markers is required.

Combination of imatinib mesylate with lithium chloride and medroxyprogesterone acetate is highly active in Ishikawa endometrial carcinoma in vitro

Objective

The aim of the study was to investigate whether lithium chloride and medroxyprogesterone acetate can potentiate the cytotoxicity of imatinib mesylate in human endometrial cancer in vitro and the effect of midkine in these therapies.

Methods

Imatinib mesylate (50 µM), lithium chloride (100 µM), medroxyprogesterone acetate (200 µM) and their combination were applied to monolayer and three dimensional cultures of human Ishikawa endometrial cancer for 72 hours. The cell proliferation index, apoptotic index, caspase-3 and midkine levels, cell cycle distributions in monolayer cultures and cell ultrastructure in spheroid cultures were evaluated. Results were statistically analyzed using the Student's t-test.

Results

All drug applications inhibited cell proliferation (p<0.05), however the combination were the effective groups for 72 hours (p<0.05). Interestingly, although the loss of efficiency was seen higly seen every 24 hours at single applications, the inhibition rates of the combination groups were almost same for 72 hours. In concordance with these results, the apoptotic index, caspase-3 levels (p<0.05), cell morphology and ultrastructure damages were much higher in the combination groups. Imatinib mesylate induced S-phase arrest, however other groups induced G0+G1-phase arrest at 24 hours and all groups induced G0+G1 arrest at 72 hours (p<0.05). Imatinib mesylate and imatinib mesylate with medroxyprogesterone acetate induced highest decrease in midkine levels, respectively (p<0.05).

Conclusion

The present study showed that the combination of imatinib mesylate with lithium chloride and medroxyprogesterone acetate is highly active in Ishikawa endometrial carcinoma in vitro and the inhibition of midkine involved in their mechanism of action against endometrium defense.

Gastrointestinal Stromal Tumors: A Guide to the Diagnosis

Gastrointestinal stromal tumors (GISTs) have emerged from being a poorly understood and therapeutically refractory sarcoma to a tumor whose biology has not only provided insight into a mechanism of oncogenesis but has also led to a rational basis for therapy. Most GISTs are characterized by KIT protein (CD117) expression and constitutive activating mutations in either the c-kit or platelet-derived growth factor receptor α genes. This information can now be obtained from routine formalin-fixed and paraffin-embedded tissue. Because the correct diagnosis is the key to successful treatment of this tumor, it is incumbent on the pathologist to be familiar with the various gross and histologic patterns shown by these tumors. GISTs range from small incidental stromal nodules to large cystic and solid tumor masses. GISTs show a variety of microscopic patterns and therefore several other tumors enter the differential diagnosis. Fortunately, with an understanding of GIST histology, and with the proper use of immunohistochemistry and molecular analysis, a correct diagnosis can usually be made. In addition to the correct diagnosis, several key attributes of the tumor need to be determined because they provide the basis for proper clinical management. This article summarizes the gross, microscopic, and molecular findings of GISTs, and discusses the differential diagnosis and key attributes of this interesting group of neoplasms.

Persistent hypomethylation in the promoter of nucleosomal binding protein 1 (Nsbp1) correlates with overexpression of Nsbp1 in mouse uteri neonatally exposed to diethylstilbestrol or genistein

Neonatal exposure of CD-1 mice to diethylstilbestrol (DES) or genistein (GEN) induces uterine adenocarcinoma in aging animals. Uterine carcinogenesis in this model is ovarian dependent because its evolution is blocked by prepubertal ovariectomy. This study seeks to discover novel uterine genes whose expression is altered by such early endocrine disruption via an epigenetic mechanism. Neonatal mice were treated with 1 or 1000 microg/kg DES, 50 mg/kg GEN, or oil (control) on d 1-5. One group of treated mice was killed before puberty on d 19. Others were ovariectomized or left intact, and killed at 6 and 18 months of age. Methylation-sensitive restriction fingerprinting was performed to identify differentially methylated sequences associated with neonatal exposure to DES/GEN. Among 14 candidates, nucleosomal binding protein 1 (Nsbp1), the gene for a nucleosome-core-particle binding protein, was selected for further study because of its central role in chromatin remodeling. In uteri of immature control mice, Nsbp1 promoter CpG island (CGI) was minimally methylated. Once control mice reached puberty, the Nsbp1 CGI became hypermethylated, and gene expression declined further. In contrast, in neonatal DES/GEN-treated mice, the Nsbp1 CGI stayed anomalously hypomethylated, and the gene exhibited persistent overexpression throughout life. However, if neonatal DES/GEN-treated mice were ovariectomized before puberty, the CGI remained minimally to moderately methylated, and gene expression was subdued except in the group treated with 1000 microg/kg DES. Thus, the life reprogramming of uterine Nsbp1 expression by neonatal DES/GEN exposure appears to be mediated by an epigenetic mechanism that interacts with ovarian hormones in adulthood.

C-kit protein expression in uterine and ovarian mesenchymal tumours

The protooncogene c-kit encoding transmembrane tyrosine kinase receptor protein plays an important role in the signal transduction pathway that regulates cellular growth and repair. Gene product KIT overexpression has been shown in a number of different neoplasms, particularly in mastocytosis and gastrointestinal stromal tumours (GIST). The morphologic similarity of uterine mesenchymal tumours and GIST, and the presence of KIT protein in normal uterine tissue, suggests that uterine sarcomas may have the same c-kit overexpression. The purpose of this study was to determine the overexpression of c-kit protein in uterine and ovarian sarcomas. Immunohistochemical staining using a polyclonal anti-c-kit antibody was performed on tissue blocks from 12 carsinosarcomas, 14 leiomyosarcomas, 8 endometrial stromal sarcomas, 2 adenosarcomas, 1 atypical leiomyoma, 1 leiomyoma with limited experience, and 10 leiomyomas. The slides were evaluated by a semiquantitative method. C-kit was positive in 10 of 12 (83%) carcinosarcomas, 10 of 14 (71%) leiomyosarcomas, 6 of 8 75(%) endometrial stromal sarcomas, 1 of 2 (50%) adenosarcomas, 1 leiomyoma with limited experience, and 1 of 10 (10%) leiomyomas. The uterine sarcomas express c-kit, like GISTs. It seems that KIT may have a significant role in the oncogenesis of mesenchymal tumours of the uterus and ovary.