Uterine sarcomas express KIT protein but lack mutation(s) in exon 11 or 17 of c-KIT

Molecular Evaluation of Low-grade Low-stage Endometrial Cancer With and Without Recurrence

Low-grade, low-stage endometrioid carcinomas (LGLS EC) demonstrate 5-yr survival rates up to 95%. However, a small subset of these tumors recur, and little is known about prognostic markers or established mutation profiles associated with recurrence. The goal of the current study was to identify the molecular profiles of the primary carcinomas and the genomic differences between primary tumors and subsequent recurrences. Four cases of LGLS EC with recurrence and 8 cases without recurrence were evaluated via whole-exome sequencing. Three of the 4 recurrent tumors were evaluated via Oncomine Comprehensive Assay. The resulting molecular profiles of the primary and recurrent tumors were compared. Two of the 3 recurrent cases showed additional mutations in the recurrence. One recurrent tumor included an additional TP53 mutation and the other recurrent tumor showed POLE and DDR2 kinase gene mutation. The POLE mutation occurred outside the exonuclease domain. PIK3CA mutations were detected in 4 of 4 primary LGLS EC with recurrence and in 3 of 8 disease-free cases. LGLS EC with recurrence showed higher MSIsensor scores compared with LGLS without recurrence. The level of copy number gains in LGLS EC with recurrence was larger than LGLS EC without recurrence. This pilot study showed 1 of 3 recurrent cases gained a mutation associated with genetic instability (TP53) and 1 of them also acquired a mutation in the DDR2 kinase, a potential therapeutic target. We also noted a higher level of copy number gains, MSIsensor scores and PIK3CA mutations in the primary tumors that later recurred.

[New features in the 2014 WHO classification of uterine neoplasms]

The 2014 World Health Organization (WHO) classification of uterine tumors revealed simplification of the classification by fusion of several entities and the introduction of novel entities. Among the multitude of alterations, the following are named: a simplified classification for precursor lesions of endometrial carcinoma now distinguishes between hyperplasia without atypia and atypical hyperplasia, the latter also known as endometrioid intraepithelial neoplasia (EIN). For endometrial carcinoma a differentiation is made between type 1 (endometrioid carcinoma with variants and mucinous carcinoma) and type 2 (serous and clear cell carcinoma). Besides a papillary architecture serous carcinomas may show solid and glandular features and TP53 immunohistochemistry with an "all or null pattern" assists in the diagnosis of serous carcinoma with ambiguous features. Neuroendocrine neoplasms are categorized in a similar way to the gastrointestinal tract into well differentiated neuroendocrine tumors and poorly differentiated neuroendocrine carcinomas (small cell and large cell types). Leiomyosarcomas of the uterus are typically high grade and characterized by marked nuclear atypia and lively mitotic activity. Low grade stromal neoplasms frequently show gene fusions, such as JAZF1/SUZ12. High grade endometrial stromal sarcoma is newly defined by cyclin D1 overexpression and the presence of the fusion gene YWHAE/FAM22 and must be distinguished from undifferentiated uterine sarcoma. Carcinosarcomas (malignant mixed Mullerian tumors MMMT) show biological and molecular similarities to high-grade carcinomas.

Review of Recommended Treatment of Uterine Carcinosarcoma

Surgery is the primary treatment for uterine carcinosarcoma (UCS). Lymphadenectomy should be performed for staging purposes in tumors apparently confined to the uterus. Most studies found that lymphadenectomy is of therapeutic value. The therapeutic value of cytoreduction to no residual macroscopic disease in advanced UCS is based mostly on small retrospective uncontrolled studies. Postoperative adjuvant therapy should be considered for all stages of UCS. Adjuvant pelvic radiotherapy may reduce locoregional recurrences. However, this does not translate into improved overall survival since most recurrences are distant outside the irradiated field, and the survival rates remain poor, the 5-year overall survival being about 50%. Several adjuvant platin-based combination chemotherapy schedules such as cisplatin/ifosfamide, ifosfamide/paclitaxel, and paclitaxel/carboplatin have been found to be an effective mode of adjuvant treatment. Multimodal therapy (i.e., adjuvant chemotherapy plus radiotherapy) has also been shown to be effective. Most studies dealing with adjuvant treatment are retrospective and prospective randomized controlled trials (i.e., phase III studies) comparing that between the various adjuvant chemotherapy schedules and between them and multimodal treatment are lacking. Quality of life with the various treatment modalities needs also to be assessed. An effective targeted therapy has so far not been found. In spite of the multiple studies with regard to the treatment of UCS published during the last 15 years, the optimal management of UCS is still not established.

Current Chemotherapy and Potential New Targets in Uterine Leiomyosarcoma

A variety of chemotherapeutic agents have been used for treating recurrent or advanced stage uterine leiomyosarcoma (ULMS). The response rates of these current agents are disappointing, with partial response rates varying from 0% to 33%, and complete response rates varying from 0% to 8%. Recent studies have documented many molecular changes in ULMSs. Prominent amongst these are gains of growth factors C-MYC, Bcl-2, K-ras, and Ki-67, and losses in tumor suppressors p16, p53, Rb1, ING2 and D14S267. Various techniques that have been used to target these molecules are presented. Targeting specific therapies at these underlying molecular changes could potentially yield better response rates with fewer side effects.

Practical issues in uterine pathology from banal to bewildering: the remarkable spectrum of smooth muscle neoplasia

Among mesenchymal tumors of the uterus, smooth muscle neoplasms are most common. The wide morphologic spectrum, especially within the category of leiomyomas, is responsible for diagnostic problems more frequently with leiomyosarcoma (including mitotically active, apoplectic, and leiomyoma with bizarre nuclei) but also with endometrial stromal tumors. In the former scenario, clinical information, gross appearance as well as strict utilization of morphologic criteria including cytologic atypia, mitotic activity, and tumor cell necrosis are clues in establishing the correct diagnosis. It is important to keep in mind that mitotic rate thresholds vary for the different subtypes of leiomyosarcoma. Of note, p16 should be used with caution in supporting a diagnosis of leiomyosarcoma as it is often positive in leiomyomas with bizarre nuclei and leiomyomas with apoplectic change (in the latter most frequently and more intense near areas of necrosis). MED12 mutations have also a very limited role in this differential diagnosis. Endometrial stromal tumors are by far, less common than smooth muscle tumors, but can be confused with leiomyosarcomas if they are associated with an undifferentiated uterine sarcoma and the low-grade component is overlooked or they have a myxoid/fibroblastic morphology. The differential diagnosis may be confounded if the latter is associated with a high-grade endometrial stromal sarcoma. It is important to highlight that CD10 is not a reliable marker in these differentials and should be used as a part of a panel of antibodies that also includes desmin and h-caldesmon. Two other recently categorized tumors in the uterus that merit special mention are PEComa and inflammatory myofibroblastic tumor as they enter in the differential diagnosis of smooth muscle tumors. PEComa may be part of the tuberous sclerosis syndrome and may show either a predominantly epithelioid or spindle morphology or combination thereof. Rarely, it may contain melanin pigment. There is variable positivity for HMB-45, MelanA, MiTF, and CathepsinK, and some tumors have been shown to express TFE-3 especially when associated with "clear cell" morphology. Patients with adverse outcome have tumors with ≥2 of the following features: ≥5 cm, infiltration, high-grade cytologic features, mitotic rate ≥1/50 high-power fields, necrosis, or lymphovascular invasion. Inflammatory myofibroblastic tumor is important to recognize as it often mimics myxoid smooth muscle tumors, either benign or malignant. The presence of an associated lymphoplasmacytic infiltrate should alert to that possibility and ALK studies (immunostain or FISH) are helpful in establishing this diagnosis. These tumors can behave in a malignant manner if large, associated with abundant myxoid change, brisk mitotic rate or show tumor cell necrosis.

Endometrial stromal tumors: the new WHO classification

Endometrial stromal tumors are rare uterine mesenchymal neoplasms that have intrigued pathologists for years, not only because they commonly pose diagnostic dilemmas, but also because the classification and pathogenesis of these tumors has been widely debated. The current World Health Organization recognizes 4 categories of endometrial stromal tumor: endometrial stromal nodule (ESN), low-grade endometrial stromal sarcoma (LG-ESS), high-grade endometrial stromal sarcoma (HG-ESS), and undifferentiated uterine sarcoma (UUS). uterine sarcoma. These categories are defined by the presence of distinct translocations as well as tumor morphology and prognosis. Specifically, the JAZF1-SUZ12 (formerly JAZF1-JJAZ1) fusion identifies a large proportion of ESN and LG-ESSs, whereas the YWHAE-FAM22 translocation identifies HG-ESSs. The latter tumors appear to have a prognosis intermediate between LG-ESS and UUS, which exhibits no specific translocation pattern. This review (1) presents the clinicopathologic features of endometrial stromal tumors; (2) discusses their immunophenotype; and (3) highlights the recent advances in molecular genetics which explain their pathogenesis and lend support for a new classification system.

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.

Diagnostic use of immunohistochemistry in uterine mesenchymal tumors

Immunohistochemistry may be helpful in the diagnosis of mesenchymal uterine tumors. This article reviews the immunoreactions used most frequently in the diagnosis of uterine smooth muscle tumors, endometrial stromal tumors, undifferentiated endometrial sarcomas, UTROSCTs, PEComas, adenomyomas, adenosarcomas and carcinosarcomas.

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.

Recent developments in uterine mesenchymal neoplasms

Smooth muscle and endometrial stromal tumours represent the two most common uterine mesenchymal neoplasms that may present diagnostic dilemmas for the practising surgical pathologist. Recent changes in morphological and staging criteria, as well as the discovery of new immunohistochemical markers, have improved the diagnosis and classification of these tumours. We highlight the difficulty in distinguishing tumour cell necrosis from infarct-type necrosis and the limited utility of p16 immunohistochemical expression in the diagnosis of leiomyosarcoma. We also discuss the controversial use of mitotic activity and necrosis as prognostic factors in endometrial stromal sarcomas. Emerging genetic information has also greatly expanded our understanding of 'sarcomagenesis' in both tumour types and may provide insight into potential therapeutic targets for the treatment of leiomyosarcoma and endometrial stromal sarcomas, harboring MED12 (mediator complex subunit 12) mutations and recurrent gene rearrangements, respectively. In this review, we discuss the core updates in the diagnosis and classification of uterine leiomyosarcomas and endometrial stromal sarcomas, highlighting new and important molecular genetic findings that may drive pathogenesis.

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.

[Update on gynecopathology]

Recent years have witnessed significant achievements in light microscopic, immunohistochemical and molecular diagnostics in gynecopathology. In this article four topics will be discussed as examples. The squamous precancerous and carcinomatous lesions of the female anogenital tract and the cervix are caused by a transforming high risk human papillomavirus (HPV) infection. No differences in morphological findings can be found between the different locations. In contrast to the current WHO classification a new categorization into low grade and high grade precancerous lesions is suggested. Only some cervical adenocarcinomas are related to high risk HPV infection. Nevertheless, some of these unusual variants demonstrate p16 overexpression. Uterine leiomyosarcomas are clinically aggressive neoplasms independent of the histological grade and in most cases curative treatment is not feasible. It is most important to distinguish leiomyosarcoma from those leiomyoma variants which mimic uterine leiomyosarcoma. Pelvic and ovarian serous carcinomas can be separated into low grade and high grade types which differ significantly in formal pathogenesis, molecular features and pathomorphological findings. Significant differences are also obvious in clinical behavior and response to chemotherapy regimens.

Epithelioid leiomyosarcoma of uterus

Fibroid most commonly presents in the reproductive age group and presence of fibroid with postmenopausal bleeding is a rare entity and all investigations and measures should be done to rule out leiomyosarcoma. A 45-year-old female had attained menopause 3 year back and developed postmenopausal bleeding since 2 months, with palpable mass, of 24 weeks size. Ultrasonography showed multiple whorled mass lesions, endometrium and myometrium could not be seen separately. Total abdominal hysterectomy with bilateral salpingoophorectomy was performed. Intraoperative findings showed 24 weeks uterine mass with size 17.5×15.5×11.5 cm and weight 1.9 kg with multiple, intramural fibroids. Cut section of removed specimen showed black and yellow necrotic and haemorrhagic areas with degenerative changes suggestive of malignancy. Histopathology reported epithelioid leiomyosarcoma.

Cell type-dependent biomarker expression in adenoid cystic carcinoma: biologic and therapeutic implications

BACKGROUND

Adenoid cystic carcinoma (ACC), a rare and progressive salivary malignancy, is characterized by cellular, morphologic, and clinical heterogeneity. The authors of this report hypothesized that the dual cellular composition of ACC plays an important role in biomarker evaluation, tumor biologic behavior, and response to therapy.

METHODS

To investigate the differential localization and expression of the c-Kit protein and the epidermal growth factor receptor (EGFR) protein, immunohistochemical analyses were performed on tissue arrays that were constructed from 199 tumors, and the results were correlated with clinicopathologic factors.

RESULTS

c-Kit expression was limited to the inner ductal epithelial cells, whereas EGFR expression was limited mainly to the outer myoepithelial cells in the majority of ACCs with tubular and cribriform patterns. In solid ACCs, c-Kit uniformly was positive, whereas EGFR consistently was negative. A significant statistical correlation was observed between c-Kit expression and a poor 3-year outcome, and EGFR expression was correlated with a better 3-year outcome.

CONCLUSIONS

The current findings underscored the importance of cellular subtype localization of biomarkers in the clinical and therapeutic stratification of patients with ACC.

Optimal management of uterine leiomyosarcoma

Uterine leiomyosarcomas (LMSs) are rare tumors, comprising 1.3% of all uterine cancers. Primary therapy for localized disease entails complete surgical resection. The majority of patients recur within 2 years of primary therapy as these tumors tend to undergo early hematogenous spread. A randomized, controlled trial showed no improvement in the overall or disease-free survival with adjuvant radiotherapy, compared with observation, following resection of early-stage uterine LMS. A Phase II study of adjuvant chemotherapy following complete surgical resection of uterine LMS reported promising results. However, in the absence of Phase III randomized data demonstrating improved outcomes, the role of post-resection chemotherapy for early-stage disease remains experimental. For metastatic or unresectable LMS, systemic chemotherapy forms the mainstay of treatment. First-line treatment options include gemcitabine-docetaxel or doxorubicin with or without ifosfamide. Novel targeted therapies are under investigation in an attempt to devise more effective treatment strategies.

Clinical management of uterine sarcomas

Malignant pure mesenchymal uterine tumours encompass endometrial stromal sarcoma (ESS), uterine leiomyosarcoma, and undifferentiated sarcomas. This Review discusses pathology, preoperative diagnosis, and standard treatment of uterine leiomyosarcoma and low-grade ESS (distinct from undifferentiated uterine sarcomas), with an emphasis on targeted treatment. We show that several features on ultrasonography and MRI can raise suspicion of a uterine sarcoma; however, there are no pathognomonic features on any imaging technique. For both ESS and uterine leiomyosarcoma, hysterectomy with bilateral salpingo-oophorectomy, but without lymphadenectomy, is the standard surgical treatment for early stage disease. The clinical benefit of chemotherapy is limited, which underscores the importance of targeted therapy. ESS and uterine leiomyosarcoma are driven by different pathways, resulting in a different clinical behaviour. ESS typically is a hormone-sensitive tumour with indolent growth. Uterine leiomyosarcoma is notorious for its aggressive growth and poor outcome. Individualisation of treatment is mandatory, because randomised trials are almost non-existent. The progesterone and oestrogen receptors are clinically important targets for most primarily advanced or recurrent ESS and a subset of recurrent uterine leiomyosarcomas. Potential future targets and targeted treatments that are under investigation are presented for both entities.

Endometrial/ioid Stromal Tumors and Related Neoplasms of the Female Genital Tract

Endometrial/ioid stromal tumors comprise a spectrum of mesenchymal neoplasms, ranging from benign to low-grade malignancy to undifferentiated sarcomas, which occur predominantly in the uterus but may rarely originate at extrauterine sites, most commonly in the ovary. These tumors and their morphologic variants are important to recognize as they often cause diagnostic difficulties. This review focuses on the diagnostic criteria and differential diagnosis, including the role of immunohistochemistry.

Molecular Genetics of Mesenchymal Tumors of the Female Genital Tract

Mesenchymal tumors of the female genital tract are a heterogeneous group of neoplasms that can be classified based on cellular differentiation into 3 main groups: smooth muscle tumors, endometrial stromal tumors, and other differentiated and undifferentiated tumors. Genomic analysis techniques have revealed important genetic aberrations such as the t(7;17) translocation, resulting in JAZF1-JJAZ1 gene fusion, characteristic of endometrial stromal tumors. These analyses have demonstrated genetic complexity and heterogeneity in many mesenchymal tumor types. This article focuses on current understanding of the molecular genetics of mesenchymal tumors of the female genital tract, with emphasis on diagnostic and prognostic molecular features.

Smooth Muscle Tumors of the Female Genital Tract

Smooth muscle tumors are the most common among mesenchymal tumors in the female genital tract. The vast majority of these neoplasms are clinically benign and easy to diagnose. In contrast, leiomyosarcomas are highly aggressive tumors that may pose considerable diagnostic problems when they display unusual (myxoid or epithelioid) morphology, ambiguous histologic features for malignancy, or an unusual anatomic distribution. Diagnostic criteria for these problematic tumors vary depending on the site and type of histologic differentiation, and are based on a combination of 3 major criteria: (1) moderate to severe cytologic atypia; (2) increased mitotic index; and (3) tumor cell necrosis. Certain benign smooth muscle proliferations may show worrisome histologic features or unusual growth patterns, causing concern for leiomyosarcoma. Furthermore, other tumors, including perivascular epithelioid tumors, may mimic leiomyosarcoma. Careful attention to the clinical and anatomic setting, cytologic and architectural features, and immunohistochemical characteristics are helpful in distinguishing these entities. This article discusses conventional smooth muscle tumors as well as unusual subtypes, with emphasis on the diagnostic criteria and problems in differential diagnosis that arise at each site within the female genital tract.

Constitutive activation of Beta-catenin in uterine stroma and smooth muscle leads to the development of mesenchymal tumors in mice

Leiomyomas and other mesenchymally derived tumors are the most common neoplasms of the female reproductive tract. Presently, very little is known about the etiology and progression of these tumors, which are the primary indication for hysterectomies. Dysregulated WNT signaling through beta-catenin is a well-established mechanism for tumorigenesis. We have developed a mouse model that expresses constitutively activated beta-catenin in uterine mesenchyme driven by the expression of Cre recombinase knocked into the Müllerian-inhibiting substance type II receptor promoter locus to investigate its effects on uterine endometrial stroma and myometrium. These mice show myometrial hyperplasia and develop mesenchymal tumors with 100% penetrance that exhibit histological and molecular characteristics of human leiomyomas and endometrial stromal sarcomas. By immunohistochemistry, we also show that both transforming growth factor beta and the mammalian target of rapamycin are induced by constitutive activation of beta-catenin. The prevalence of the tumors was greater in multiparous mice, suggesting that their development may be a hormonally driven process or that changes in uterine morphology during pregnancy and after parturition induce injury and repair mechanisms that stimulate tumorigenesis from stem/progenitor cells, which normally do not express constitutively activated beta-catenin. Additionally, adenomyosis and endometrial gland hyperplasia were occasionally observed in some mice. These results show evidence suggesting that dysregulated, stromal, and myometrial WNT/beta-catenin signaling has pleiotropic effects on uterine function and tumorigenesis.

Gastrointestinal stromal tumor of the uterus: a case report with genetic analyses of c-kit and PDGFRA genes

The author reports a very rare case of a gastrointestinal stromal tumor in the uterus. A 74-year-old woman was admitted to our hospital because of pelvic pain. Imaging modalities showed a large tumor of the posterior aspect of the uterus, and enucleation was performed. The tumor was attached to the posterior uterus, similar to subserosal leiomyoma. No attachment to the gastrointestinal organs was recognized. The tumor was soft, tan, and measured 13 x 15 x 12 cm. The tumor consisted of cellular spindle cells with focal necrotic areas. Mitotic figures were noted in 3 of 50 high-power fields. The tumor cells were positive for KIT, CD34, platelet-derived growth factor receptor alpha, and vimentin, but negative for alpha-smooth muscle actin, S100 protein, p53 protein, HMB45, and desmin. Ki-67 labeling was 3%. Five normal uteruses used as controls showed KIT-positive Cajal-like mesenchymal cell scattering in the myometrium. Genetic analyses of the c-kit gene (exons 9, 11, 13, and 17) and platelet-derived growth factor receptor alpha gene (exons 12 and 18) revealed a point mutation at codon 559 (GTT-->GAT) of exon 11 of the c-kit gene. Other exons showed no abnormalities. This case shows that gastrointestinal stromal tumor may occur in the uterus.

Application of immunohistochemistry to gynecologic pathology

CONTEXT

A large variety of tumors and lesions arise in the female genital tract. Although the majority of these can be correctly recognized on routine hematoxylin-eosin-stained slides, occasional cases present a diagnostic challenge. Immunohistochemical stains are extremely useful in resolving many of these problematic cases. As the knowledge in this area is constantly expanding, it is useful to have this updated information in a review form for easy access.

OBJECTIVE

To present our current knowledge of immunohistochemistry of the lesions of the female genital tract in a readily accessible form.

DATA SOURCES

The review is based on previously published articles on this topic.

CONCLUSIONS

Immunohistochemical stains help in reaching a conclusive diagnosis in a variety of problematic lesions seen in gynecologic pathology. As in any other system, immunohistochemical findings need to be interpreted in light of the clinical history and morphologic findings.

Gynaecological sarcomas

PURPOSE OF REVIEW

To review gynaecological sarcomas, their management and future perspectives.

RECENT FINDINGS

Soft tissue sarcomas are a group of tumours consisting of a wide variety of subtypes. The most common subtypes encountered in the female tract are uterine leiomyosarcomas and endometrial stromal sarcomas. Other subtypes do occur but at a much lower frequency. Mixed Müllerian tumours were previously considered to be a subtype of sarcoma, but recent evidence has revealed that they should in fact be regarded as carcinomas. Given the different approaches for different subtypes of sarcomas, their rarity and the complexity of treatment, the management of patients with gynaecological sarcomas should be delivered by multidisciplinary teams experienced in the treatment of these entities.

SUMMARY

Gynaecological sarcomas are rare tumours and are treated differently from gynaecological carcinomas. Hopefully, improved insight into the pathogenesis of gynaecological sarcomas will yield novel therapies in the near future.

Ovarian spindle cell lesions: a review with emphasis on recent developments and differential diagnosis

Ovarian lesions composed of spindle cells comprise a heterogeneous group; most are neoplastic but several non-neoplastic conditions are also composed of spindle cells. This review discusses the main differential diagnoses of an ovarian spindle cell lesion, especially concentrating on the recent literature. The majority of ovarian spindle cell lesions fall into the broad category of fibromatous neoplasms whereas others in the sex cord-stromal group may also be composed of spindle cells, including thecomas, granulosa, and Sertoli-Leydig cell tumors and rarer neoplasms, such as sclerosing stromal tumor and signet-ring stromal tumor. In the recent past there have been several major contributions on various aspects of ovarian spindle cell lesions, including cellular and mitotically active cellular fibromatous lesions, smooth muscle neoplasms, and metastatic gastrointestinal stromal tumors. Other mesenchymal or epithelial tumors and mixed epithelial and mesenchymal neoplasms may also enter into the differential diagnosis of an ovarian spindle cell lesion. Several non-neoplastic lesions may be composed of spindle cells, including massive edema, ovarian fibromatosis, stromal hyperplasia, and stromal hyperthecosis. Morphology remains the mainstay in diagnosis but immunohistochemistry may be invaluable in certain circumstances, one example being the identification of a metastatic gastrointestinal stromal tumor within the ovary.

Expression of cyclooxygenase-2, c-kit, progesterone and estrogen receptors in uterine smooth muscle tumors: differential diagnosis

We examined the expression pattern of cyclooxygenase-2 (COX-2) and c-kit in uterine smooth muscle neoplasms and tried to determine the role of these markers in differential diagnosis. Archival tissue from 64 patients with uterine smooth muscle neoplasms (20 leiomyomas (LMs), 22 atypical leiomyomas (ALMs), and 22 leiomyosarcomas (LMSs)) was immunostained with antibodies against estrogen (ER) and progesterone receptors (PR), COX-2 and c-kit. 7 of 20 LM cases and 5 of 22 ALM cases were immunopositive for COX-2, whereas none of the LMS cases stained immunopositive (p< or =0.05). 4 of 20 LM cases and 5 of 22 ALM cases were immunopositive for c-kit, whereas 15 of 22 LMS cases showed c-kit immunopositivity (p< or =0.05). In conclusion, very few LMs and ALMs show COX-2 immunopositivity. LMSs usually do not express COX-2. COX-2 expression in smooth muscle tumors is not a prominent feature. Therefore, COX-2 inhibitors may not be useful in LMS therapy. C-kit was significantly expressed in uterine LMSs.

The management of patients with uterine sarcoma: a debated clinical challenge

Uterine sarcomas include a heterogeneous group of rare tumours that usually have an aggressive clinical behaviour and a poor prognosis. Total abdominal hysterectomy and bilateral salpingo-oophorectomy represents the standard surgical treatment. Pelvic and/or para-aortic lymphadenectomy is indicated for carcinosarcoma, but not for leiomyosarcoma and undifferentiated endometrial sarcoma. Some recent data on low numbers of patients with low-grade endometrial stromal sarcoma appear to show an incidence of nodal involvement higher than previously expected, thus suggesting a role for lymphadenectomy in this malignancy. Carcinosarcoma also requires a comprehensive surgical peritoneal staging. Postoperative treatment of uterine sarcomas has been long debated. Adjuvant pelvic radiotherapy appears to improve local control without any significant impact on overall survival. There is little evidence in the literature supporting the use of adjuvant chemotherapy in any gynaecological sarcomas except for carcinosarcomas. However, uterine sarcomas have a high tendency to develop distant recurrences, and recent data on adjuvant chemotherapy in soft tissue sarcomas are promising. As for the drugs to be used, it is worth noting that in a Swiss study, the combination of ifosfamide (IFO) and doxorubicin (DOX) obtained similar response rates in advanced gynaecological sarcomas and in advanced soft tissue sarcomas of other sites. In our decision-making scheme for early-stage disease, patients with leiomyosarcoma or undifferentiated endometrial sarcoma should receive adjuvant doxorubicin/epidoxorubicin (EPIDX)+ifosfamide, and those with carcinosarcoma should be treated with adjuvant cisplatin (CDDP)-based chemotherapy. The same drug regimens are used for the treatment of advanced disease. Sequential pelvic radiotherapy following chemotherapy could be delivered to selected cases. Recurrent disease often requires the integration of different therapeutic modalities, but no curative option is currently available with the possible exception of surgery for lung metastases and hormone therapy with or without debulking surgery for recurrent low-grade endometrial stromal sarcoma. Patients should be encouraged to enter clinical trials designed to identify new active drugs for these malignancies.

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.

Adult human sarcomas. II. Medical oncology

Human sarcoma cells can be killed by radio- and chemotherapy, but tumor cells acquiring resistance frequently kill the patient. A keen understanding of the intracellular course of oncogenic cascades leads to the discovery of small molecular inhibitors of the involved phosphorylated kinases. Targeted therapy complements chemotherapy. Oncogene silencing is feasible by small interfering RNA. The restoration of some of the mutated or deleted tumor-suppressor genes (p53, Rb, PTEN, hSNF, INK/ARF and WT) by demethylation or reacetylation of their histones has been accomplished. Genetically engineered or naturally oncolytic viruses selectively lyse tumors and leave healthy tissues intact. Adeno- or retroviral vectors deliver genes of immunological costimulators, tumor antigens, chemo- or cytokines and/or tumor-suppressor proteins into tumor (sarcoma) cells. Suicide gene delivery results in apoptosis induction. Genes of enzymes that target prodrugs as their substrates render tumor cells highly susceptible to chemotherapy, with the prodrug to be targeted intracellularly. It will be combinations of sophisticated surgical removal of the nonencapsulated and locally invasive primary sarcomas, advanced forms of radiotherapy to the involved sites and immunotherapy with sarcoma vaccines that will cure primary sarcomas. Adoptive immunotherapy with immune lymphocytes will be operational in metastatic disease only when populations of regulatory T cells are controlled. Targeted therapy with small molecular inhibitors of oncogene cascades, the driving forces of sarcoma cells, alteration of the tumor stroma from a supportive to a tumor-hostile environment, reactivation or replacement of wild-type tumor-suppressor genes, and radio-chemotherapy (with much reduced toxicity) will eventually accomplish the cure of metastatic sarcomas.

PDGFR-α as a potential therapeutic target in uterine sarcomas

OBJECTIVE

Uterine sarcomas are a heterogeneous group of tumors with a propensity for metastasis and resistance to conventional therapy. Recent success in the treatment of other solid tumors with the targeted tyrosine kinase inhibitor imatinib mesylate offers new avenues for investigation. The primary target of imatinib is c-kit, but the drug also inhibits PDGFR-alpha and PDGFR-beta. Given the lack of identified molecular targets in endometrial stromal sarcomas, leiomyosarcomas, and carcinosarcomas, the purpose of this study was to determine the protein expression of c-kit, PDGFR-alpha, and PDGFR-beta in these tumors as a preliminary step to determining their susceptibility to directed therapy. A secondary goal was to identify specific gene mutations that might be associated with activation of these proteins in uterine sarcomas.

METHODS

Archived tissue from 42 cases of uterine sarcomas was stained for c-kit, PDGFR-alpha, and PDGFR-beta using immunohistochemistry. Laser-capture microdissected samples of uterine carcinosarcomas, or homogeneous areas of leiomyosarcomas or endometrial stromal sarcomas, were subjected to genetic analysis of PDGFR-alpha exons 12 and 18.

RESULTS

The majority (38/42, 90%) of uterine sarcomas lacked c-kit expression and 90% (38/42) demonstrated negative or weak staining for PDGFR-beta. In contrast, 70% (30/42) of cases had strong staining for PDGFR-alpha in the tumor but not in normal myometrium or endometrium. Sequencing results revealed no mutations in exons 12 or 18 of PDGFR-alpha.

CONCLUSION

c-kit and PDGFR-beta are unlikely to represent primary treatment targets in uterine sarcomas. The strong expression of PDGFR-alpha in uterine sarcoma specimens suggests a role for this receptor in tumor development, although its potential as a therapeutic target requires further investigation.

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

BACKGROUND

High-grade endometrial stromal sarcoma (HGES) is an aggressive disease with dismal prognosis. Surgery is the standard treatment, and radiotherapy seems to reduce local relapse. No other treatment has proved to be useful in the case of non-resectable diseases.

CASE

A 41-year-old woman suffering HGES, with positive staining for CD117 (c-kit) and large abdominal and retroperitoneal mass progressing after chemotherapy, was treated with Imatinib Mesylate. After 3 months, objective response was documented and radical surgery performed. Two years after surgical intervention, she is currently free of the disease.

CONCLUSION

The response seen with Imatinib should be further investigated in a larger number of cases.

Differential KIT expression in histological subtypes of adenoid cystic carcinoma (ACC) of the salivary gland

Adenoid cystic carcinoma (ACC) of the salivary gland is characterized by a prolonged but inevitably unfavorable clinical course. Recent studies suggested the transmembrane tyrosine kinase KIT to be involved in ACC pathogenesis. To investigate KIT expression in histologically defined subgroups of ACC and to clarify whether KIT gene copy number gain contributes to KIT overexpression, tumor tissue microarray sections including 55 ACC tumors were analyzed by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC). The prevalence of positive KIT immunostaining was 89% (49/55). Strong immunostaining of KIT was only found in cribriform and tubular but never in solid subtypes (p=0.02). Average KIT staining intensity was higher in cribriform and tubular (n=37) compared to solid (n=18) ACC subtypes (p=0.005). FISH analysis revealed copy number gains of the KIT gene in 6.1% (3/49) of tumors analyzed. Our results implicate that specific KIT tyrosine kinase inhibitors such as imatinib, might be used in future therapeutic approaches against subgroups of ACC.

Immunohistochemical evaluation of KIT expression in sarcomas of the gynecologic region

KIT is expressed in most gastrointestinal stromal tumors, and they usually show c-kit aberrations (most frequently deletions or deletions coexisting with a single or multiple point mutations). Recently, several studies regarding KIT expression in gynecologic tumors have been reported; however, their outcomes were not consistent. In this study, we immunohistochemically examined KIT expression in sarcomas of the female genital tract and studied the existence of c-kit aberrations to elucidate the characteristics of KIT-positive tumors in the gynecologic region. Formalin-fixed, paraffin-embedded tissues from 25 surgically resected and 1 biopsy specimen from 26 patients were used. Histological diagnoses included 14 uterine leiomyosarcomas, 6 carcinosarcomas, 5 endometrial stromal sarcomas, and 1 vaginal epithelioid sarcoma. Immunohistochemical studies were performed using anti-KIT polyclonal antibody. Only four of the above tumors (15%) were positive for KIT, all of which were carcinosarcomas. Specific KIT immunoreactivity was observed in the only carcinomatous components in one case, in the only sarcomatous component in two cases, and in the both components in one case. However, none of the cases showed c-kit aberrations in exons 9, 11, 13, and 17. Judicious decision is mandatory before applying Imatinib therapy to KIT-positive gynecologic tumors.

KIT (CD117): a review on expression in normal and neoplastic tissues, and mutations and their clinicopathologic correlation

CD117 (KIT) is a type III receptor tyrosine kinase operating in cell signal transduction in several cell types. Normally KIT is activated (phosphorylated) by binding of its ligand, the stem cell factor. This leads to a phosphorylation cascade ultimately activating various transcription factors in different cell types. Such activation regulates apoptosis, cell differentiation, proliferation, chemotaxis, and cell adhesion. KIT-dependent cell types include mast cells, some hematopoietic stem cells, germ cells, melanocytes, and Cajal cells of the gastrointestinal tract, and neoplasms of these cells are examples of KIT-positive tumors. Other KIT-positive normal cells include epithelial cells in skin adnexa, breast, and subsets of cerebellar neurons. KIT positivity has been variably reported in sarcomas such as angiosarcoma, Ewing sarcoma, synovial sarcoma, leiomyosarcoma, and MFH; results of the last three are controversial. The variations in published data may result from incomplete specificity of some polyclonal antibodies, possibly contributed by too high dilutions. Also, KIT is expressed in pulmonary and other small cell carcinomas, adenoid cystic carcinoma, renal chromophobe carcinoma, thymic, and some ovarian and few breast carcinomas. A good KIT antibody reacts with known KIT positive cells, and smooth muscle cells and fibroblasts are negative. KIT deficiency due to hereditary nonsense/missense mutations leads to disruption of KIT-dependent functions such as erythropoiesis, skin pigmentation, fertility, and gastrointestinal motility. Conversely, pathologic activation of KIT through gain-of-function mutations leads to neoplasia of KIT-dependent and KIT-positive cell types at least in three different systems: mast cells/myeloid cells--mastocytosis/acute myeloid leukemia, germ cells--seminoma, and Cajal cells--gastrointestinal stromal tumors (GISTs). KIT tyrosine kinase inhibitors such as imatinib mesylate are the generally accepted treatment of metastatic GISTs, and their availability has prompted an active search for other treatment targets among KIT-positive tumors such as myeloid leukemias and small cell carcinoma of the lung, with variable and often nonconvincing results.

C-kit immunopositive interstitial cells (Cajal-type) in human myometrium

Previous reports describing Cajal-like interstitial cells in human uterus are contradictory in terms of c-kit immunoreactivity: either negative (but vimentin-positive) in pregnant myometrium, or positive, presumably in the endometrium. The aim of this study was to verify the existence of human myometrial Cajal-like interstitial cells (m-CLIC). Six different, complementary approaches were used: 1) methylene-blue supravital staining of tissue samples (cryosections), 2) methylene blue and Janus green B vital staining (m-CLIC and mitochondrial markers, respectively), and 3) extracellular single-unit electrophysiological recordings in cell cultures, 4) non-conventional light microscopy on glutaraldehyde/osmium fixed, Epon-embedded semi-thin sections (less than 1 microm) stained with toluidine blue (TSM), 5) transmission electron microscopy (TEM), and 6) immunofluorescence (IF). We found m-CLIC in myometrial cryosections and in cell cultures. In vitro, m-CLIC represented approximately 7% of the total cell number. m-CLIC had 2-3 characteristic processes which were very long (approximately 60 microm), very thin (< or =0.5 microm) and moniliform. The dilated portions of processes usually accommodated mitochondria. In vitro, m-CLIC exhibited spontaneous electrical activity (62.4+/-7.22 mV membrane potentials, short duration: 1.197+/-0.04 ms). Moreover, m-CLIC fulfilled the usual TEM criteria, the so-called 'gold' or 'platinum' standards (e.g. the presence of discontinuous basal lamina, caveolae, endoplasmic reticulum, and close contacts between each other, with myocytes, nerve fibers and/or capillaries etc.). IF showed that m-CLIC express CD117/c-kit, sometimes associated with CD34, with vimentin along their processes. In conclusion, we describe myometrial Cajal-like interstitial cells that have affinity for methylene blue and Janus green B vital dyes, fulfill (all) TEM criteria, express CD117/c-kit and have spontaneous electric activity.

Gastrointestinal stromal tumors metastatic to the ovary: a report of five cases

Five cases of gastrointestinal stromal tumor metastatic to the ovary are reported. The average patient age was 59 years (range, 44-81 years). The primary tumor was in the small bowel or its mesentery (4 cases) or stomach (1 case). The primary and metastatic tumors were discovered synchronously in 3 cases. In the other 2 cases, the ovarian tumors were discovered 18 months before a gastric tumor was identified and 27 years after a small bowel tumor had been resected. The ovarian tumors (three of which were bilateral) were usually solid, tan, and lobulated. Microscopically, three tumors had a pure spindle cell morphology, and two both spindle and epithelioid cell components. The diagnosis in all 5 cases was confirmed with positive c-kit (CD117) and negative desmin immunostaining. Variably positive immunoreactivity for either or both h-caldesmon and smooth muscle actin was seen in all 5 cases, and 3 cases were CD34-positive. Four patients died between 1 and 6.5 years (mean, 2.8 years) from the time of ovarian tumor diagnosis. The main differential diagnostic consideration was leiomyosarcoma; the most important features to help exclude this diagnosis were an absence of tumor in the uterus, low histologic grade, and a desmin-negative, c-kit-positive immunophenotype. Other differential considerations, including endometrial stromal sarcoma and fibrosarcoma, are discussed. Most of the ovarian tumors in this series were initially diagnosed as tumors of other types, a misdiagnosis with significant therapeutic and prognostic implications because of the specific therapy now available for gastrointestinal stromal tumors.

Imatinib Mesylate (Gleevec)-Targeted Kinases Are Expressed in Uterine Sarcomas

The purpose of this study was to determine whether 3 tyrosine kinases known to be inhibited by imatinib mesylate are expressed in a variety of uterine sarcomas. The authors assessed c-kit, abl, and platelet-derived growth factor receptor-beta (PDGFR-beta) expression in 8 endometrial stromal sarcomas (ESSs), 5 leiomyosarcomas (LMSs), 4 high-grade endometrial sarcomas (HGESs), and 21 malignant mixed mullerian tumors (MMMTs). Tissue sections were stained with commercially available antibodies for c-kit, abl, and PDGFR-beta. Staining intensity was described as 0 (no staining), +1 (weak), +2 (moderate), and +3 (strong). Positive staining was defined as moderate to strong if found in more than 10% of tumor cells. Expression of c-kit ranged from 0% in LMSs to 25% in HGESs. Protein expression of abl was more significant, ranging from 25% in LMSs and ESSs to 43% in MMMTs. Only 1 LMS sample stained focally for abl (+1). Abl expression was observed in only the carcinomatous elements of the MMMTs, with diffuse staining in the cytoplasm and nucleus. In most, the staining intensity was +2. All tumors stained positive for PDGFR-beta. MMMT samples showed PDGFR-beta expression in both the carcinomatous and sarcomatous portions. In all samples, staining for PDGFR-beta was concentrated at the cell membrane and diffusely in the cytoplasm. These results indicate that many uterine sarcomas express 1 or more of the kinases targeted by imatinib mesylate and that further investigation of imatinib as a therapy for uterine sarcomas is warranted.