The pathology of uterine smooth muscle tumors and mixed endometrial stromal-smooth muscle tumors: a selective review with emphasis on recent advances

Targeted RNA Sequencing Highlights a Diverse Genomic and Morphologic Landscape in Low-grade Endometrial Stromal Sarcoma, Including Novel Fusion Genes

Low-grade endometrial stromal sarcoma (LGESS) represents a morphologically and genetically heterogenous mesenchymal neoplasm. Previous work has shown that approximately half of LGESS are characterized by JAZF1::SUZ12 gene fusions, while a smaller proportion involves rearrangement of other genes. However, a subset of cases has no known genetic abnormalities. To better characterize the genomic landscape of LGESS, we interrogated a cohort with targeted RNA sequencing (RNA-Seq). Cases previously diagnosed as low-grade endometrial stromal neoplasia (n=51) were identified and re-reviewed for morphology and subjected to RNA-Seq, of which 47 were successfully sequenced. The median patient age was 49 years (range: 19 to 85). The most commonly detected fusions were JAZF1::SUZ12 (n=26, 55%) and BRD8::PHF1 (n=3, 6%). In addition to the usual/typical LGESS morphology, some JAZF1::SUZ12 fusion tumors showed other morphologies, including fibrous, smooth muscle, sex-cord differentiation, and myxoid change. Novel translocations were identified in 2 cases: MEAF6::PTGR2 and HCFC1::PHF1 . Ten tumors (21%) had no identifiable fusion, despite a similar morphology and immunophenotype to fusion-positive cases. This suggests that a subset of cases may be attributable to fusion products among genes that are not covered by the assay, or perhaps altogether different molecular mechanisms. In all, these findings confirm that RNA-Seq is a potentially useful ancillary test in the diagnosis of endometrial stromal neoplasms and highlight their diverse morphology.

Highly cellular leiomyoma - A great histopathological masquerader of endometrial stromal sarcoma

ABSTRACT

Leiomyoma is the most common benign uterine tumor, whereas endometrial stromal tumors are rare uterine tumors with limited clinical experience. The distinction between highly cellular leiomyoma and endometrial stromal sarcoma can pose a diagnostic challenge to the pathologists as both these tumors have considerable overlapping features on histology.

Management of a giant uterine smooth muscle tumor of uncertain malignant potential in a 32-year-old woman: case report and review of the literature

Uterine smooth muscle tumors of uncertain malignant potential (STUMP) represent a group of rare uterine smooth muscle tumors not diagnosed unequivocally as benign or malignant. To data, diagnostic criteria, malignant potential, surgical management, and follow-up of these neoplasms remain controversial. Considering that STUMP and leiomyoma are not significantly different in terms of clinical presentation and preoperative sonographic characteristics, it might be difficult to distinguish between the two affections prior to pathological confirmation at surgery. All cases should be managed by multidisciplinary tumor teams and patients' follow-up should comprise consultation with a gynecologic oncologist and a close surveillance because of the possibility of recurrence or metastasis. We present the case of a 32-year-old nulliparous woman admitted to our gynecology clinic. She was asymptomatic and only complained an increase in abdominal volume started during the past 6 months. A transabdominal and transvaginal pelvic ultrasound revealed a large heterogeneous tumor mass measuring 190×163 mm, color score 2, expanded in the left iliac fossa, suspected for benign uterine myoma. Subsequent magnetic resonance imaging confirmed a large pelvic-abdominal tumor located near the left posterior-lateral uterine wall with areas of necrosis, suggestive of subserosal leiomyoma with cystic degeneration. The patient underwent a median longitudinal laparotomy for excision of the pelvic mass. The patient was normally discharged five days after surgery in good health conditions. The final histological examination was compatible with STUMP. At present, the patient has had no relapses or metastases and she is undergoing follow-up.

Review of uterine fibroids: imaging of typical and atypical features, variants, and mimics with emphasis on workup and FIGO classification

Uterine fibroids are the most common gynecologic neoplasm. Although non-degenerated fibroids are easily identifiable on imaging, degenerated fibroids, fibroid variants, and fibroids with unusual growth patterns can constitute a diagnostic dilemma. Identification of these abnormal morphologic features can alter the diagnosis of presumed uterine fibroids and hence change management plans. This article reviews the typical and atypical radiologic imaging features of uterine fibroids, with an emphasis on the pitfalls, mimics, and radiologically identifiable features that can alter clinical management plans.

[Interdisciplinary S2k guidelines on the diagnosis and treatment of uterine sarcomas-recommendations for surgical pathology]

Uterine sarcomas represent a heterogeneous group of rare malignancies, derived from the myometrium, the endometrial stroma, and very rarely from the nonspecialized uterine soft tissue. The actual incidence is about 1.5 for Caucasian and 3.0 for Afro-American women. There is no grading system for leimoysarcoma defined by the WHO classification; however, if clinicians request, the FNCLCC grading can be specified in analogy to soft tissue sarcomas. Adenosarcomas must be distinguished from adenofibromas (the existence of which is questionable)-with the vast majority of these tumors being uterine adenosarcomas. Within adenosarcomas, deep myometrial invasion (>50%), sarcomatous overgrowth, and a high-grade heterologous component are associated with a higher recurrence rate and poor survival. The immunohistochemical panel represents a very helpful tool for distinguishing low-grade from high grade endometrial stromal sarcomas (ESS) and may be supplemented by molecular analyses. Steroid hormone receptor analysis should be performed for all ESS due to the possible therapeutic relevance. Undifferentiated uterine sarcomas represent a diagnosis of exclusion and have a very poor prognosis. Carcinosarcomas represent a special subtype of endometrial carcinomas and are in fact not uterine sarcomas. Uterine sarcomas may present substantial intratumoral heterogeneity and adequate embedding is mandatory. Lesions ≤2 cm in the largest dimension should be processed completely and larger tumors should be processed with one block per centimeter for the largest tumor dimension.

Molecular and clinicopathologic characterization of intravenous leiomyomatosis

Intravenous leiomyomatosis (IVL) is an unusual uterine smooth muscle proliferation that can be associated with aggressive clinical behavior despite a histologically benign appearance. It has some overlapping molecular characteristics with both uterine leiomyoma and leiomyosarcoma based on limited genetic data. In this study, we assessed the clinical and morphological characteristics of 28 IVL and their correlation with molecular features and protein expression, using array comparative genomic hybridization (aCGH) and Cyclin D1, p16, phosphorylated-Rb, SMARCB1, SOX10, CAIX, SDHB and FH immunohistochemistry. The most common morphologies were cellular (n = 15), usual (n = 11), and vascular (n = 5; including 3 cellular IVL showing both vascular and cellular features). Among the immunohistochemical findings, the most striking was that all IVL showed differential expression of either p16 or Cyclin D1 in comparison to surrounding nonneoplastic tissue. Cytoplasmic phosphorylated-Rb was present in all but one IVL with hyalinization. SMARCB1, FH, and SDHB were retained; S0X10 and CAIX were not expressed. The most common genetic alterations involved 1p (39%), 22q (36%), 2q (29%), 1q (25%), 13q (21%), and 14q (21%). Hierarchical clustering analysis of recurrent aberrations revealed three molecular groups: Groups 1 (29%) and 2 (18%) with associated del(22q), and Group 3 (18%) with del(10q). The remaining IVL had nonspecific or no alterations by aCGH. Genomic index scores were calculated for all cases and showed no significant difference between the 14 IVL associated with aggressive clinical behavior (extrauterine extension or recurrence) and those without (median scores 5.15 vs 3.5). Among the 5 IVL associated with recurrence, 4 had a vascular morphology and 3 had alterations of 8q. Recurrent chromosome alterations detected herein overlap with those observed in the spectrum of uterine smooth muscle tumors and involve genes implicated in mesenchymal tumors at different sites with distinct morphological features.

Clinical experience of uterine smooth muscle tumor of uncertain malignant potential in two gynecological centers: Oncological and obstetrical aspects

OBJECTIVES

To evaluate the clinical characteristics and obstetrical and oncological outcomes of patients with uterine smooth muscle tumors of uncertain malignant potential (STUMP) and analyze the risk factors for recurrence.

STUDY DESIGN

A retrospective cohort study was performed at two gynecological centers using data collected between January 2008 and August 2018. All the patients enrolled were diagnosed with STUMP and had been followed up for at least 6 months. The patients' characteristics, treatment methods, recurrence rate, and subsequent pregnancy outcomes were evaluated.

RESULTS

The mean age of the 62 patients was 36.1 ± 9.1 years (median 35, range 20-55 years) and mean follow-up duration was 36.3 ± 26.8 months (29.5, 6-130). All the patients were of premenopausal status. Fourteen patients (22.6 %) were initially treated by hysterectomy and 48 (77.4 %) by myomectomy. During the study period, three patients (4.8 %) experienced recurrence. However, there was no statistical difference between myomectomy and hysterectomy in terms of the rate of recurrence of STUMP or sarcoma, and all patients survived even after recurrence. Multivariate analysis revealed that a history of previous myomectomy was the sole independent risk factor for recurrence (odds ratio = 51.071; 95 % confidence interval = 2.743-950.726; p = 0.008). Subsequent pregnancies were successful in 10 of 19 women (52.6 %) who tried to conceive. Two of them had ongoing pregnancies at the time of last follow-up; the remaining eight women experienced a total of 14 subsequent pregnancies.

CONCLUSIONS

The recurrence rate of STUMP was similar between hysterectomy and myomectomy. Therefore, fertility sparing myomectomy can be considered in women diagnosed with STUMP with close monitoring.

Sarcoma of the Uterus. Guideline of the DGGG and OEGGG (S2k Level, AWMF Register Number 015/074, February 2019)

Aims This is an official guideline published and coordinated by the German Society of Gynecology and Obstetrics (DGGG) and the Austrian Society of Gynecology and Obstetrics (OEGGG). Because of their rarity and heterogeneous histopathology, uterine sarcomas are challenging in terms of how they should be managed clinically, and treatment requires a multidisciplinary approach. To our knowledge, there are currently no binding evidence-based recommendations for the appropriate management of this heterogeneous group of tumors. Methods This S2k guideline was first published in 2015. The update published here is the result of the consensus of a representative interdisciplinary group of experts who carried out a systematic search of the literature on uterine sarcomas in the context of the guidelines program of the DGGG, OEGGG and SGGG. Members of the participating professional societies achieved a formal consensus after a moderated structured consensus process. Recommendations The consensus-based recommendations and statements include the epidemiology, classification, staging, symptoms, general diagnostic work-up and general pathology of uterine sarcomas as well as the genetic predisposition to develop uterine sarcomas. Also included are statements on the management of leiomyosarcomas, (low and high-grade) endometrial stromal sarcomas and undifferentiated uterine sarcomas and adenosarcomas. Finally, the guideline considers the follow-up and morcellation of uterine sarcomas and the information provided to patients.

Uterine smooth muscle tumors of unknown malignant potential: A challenging question

Uterine smooth muscle tumors of unknown malignant potential [STUMP]s are neoplasms with pathological features that preclude an equivocal diagnosis of leiomyosarcoma, but that do not fulfill the criteria for leiomyoma or its variants, and raise concerns that the tumors may behave in a malign fashion. Total hysterectomy with or without bilateral salpingo-oophorectomy is the standard treatment if fertility is completed, whereas myomectomy alone can be taken into consideration in young patients who desire to preserve childbearing potential. A careful surveillance every 6 months for 5 years and then yearly is strongly warranted. Patients with STUMP can relapse as either STUMP or leiomyosarcoma in approximately 11-13% of the cases, and their 5-year overall survival ranges from 92 to 100%. The present paper reviews the clinicopathological features of uterine STUMPs with a particular focus on most commonly accepted histopathological criteria for the diagnosis and on biological behaviour of these controversial neoplasms.

Intrauterine photoacoustic and ultrasound imaging probe

Intrauterine photoacoustic and ultrasound imaging are probe-based imaging modalities with translational potential for use in detecting endometrial diseases. This deep-tissue imaging probe design allows for the retrofitting of commercially available endometrial sampling curettes. The imaging probe presented here has a 2.92-mm diameter and approximate length of 26 cm, which allows for entry into the human endometrial cavity, making it possible to use photoacoustic imaging and high-resolution ultrasound to characterize the uterus. We demonstrate the imaging probes' ability to provide structural information of an excised pig uterus using ultrasound imaging and detect photoacoustic signals at a radial depth of 1 cm.

Proposed novel nomenclature of vulvar smooth muscle tumors; a case of Smooth Muscle Tumor of Uncertain Malignant Potential (STUMP) of the vulva

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Clinical experience with smooth muscle tumors of the vulva is limited.

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Some tumors present ambiguous histological features concerning for malignancy.

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These include infiltration, mitotic activity, size, atypia and tumor cell necrosis.

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A case of smooth muscle tumor of the vulva with cellular atypia is presented.

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“Smooth Muscle Tumor of Uncertain Malignant Potential” of the vulva is advocated.

MR imaging of atypical fibroids

Leiomyomas are the most common neoplasm found in the uterus and can present with a variety of symptoms or be entirely asymptomatic. Most often, the characteristic imaging appearance of leiomyoma does not pose a diagnostic dilemma. However, leiomyomas can demonstrate atypical imaging features that may be confusing. It is essential for the radiologist to be aware of both the typical and atypical findings to better assist the referring clinician with diagnosis and management decisions. Additionally, as uterine-sparing treatment alternatives with locoregional therapies become more popular, it is important to be aware of pre- and post-procedural imaging questions that may be encountered. Lastly, when atypical features are seen, it is important to understand the characteristics that may suggest a diagnosis of leiomyosarcoma. The goal of this study is to review imaging features of atypical leiomyoma with case-based examples.

Bcl-2 Receptor Expression in Patients With Uterine Smooth Muscle Tumors: An Immunohistochemical Analysis Comparing Leiomyoma, Uterine Smooth Muscle Tumor of Uncertain Malignant Potential, and Leiomyosarcoma

OBJECTIVE

Bcl-2 protein is an apoptosis-inhibiting gene product that prevents the normal course of apoptotic cell death in a variety of cells. Additionally, bcl-2 can promote cell replication by reducing the requirement for growth factors. This protein seems, therefore, to play an important role in the growth of tumors. Our aim was to investigate the different expression of bcl-2 in uterine leiomyomas, smooth muscle tumors of uncertain malignant potential (STUMP), and leiomyosarcomas (LMS). Furthermore, the correlation between bcl-2 expression and various clinicopathologic parameters in leiomyosarcomas was assessed to evaluate its prognostic value.

METHODS

This study included 26 cases of leiomyoma, 22 cases of STUMP, and 21 cases of LMS of the uterus. Bcl-2 expression was investigated by immunohistochemistry from paraffin-embedded tissue. The immunohistochemical findings were compared and correlated with different clinicopathologic parameters. Clinical information, including follow-up data, was obtained from the database of the Department of Gynecology and Obstetrics.

RESULTS

Bcl-2 was present in 12 of 21 LMS, eight of 22 STUMP, and 20 of 25 leiomyomas. Significant differences regarding the frequency of bcl-2 expression and the staining intensity were observed between LMS and leiomyoma as well as between STUMP and leiomyoma (P <.05) but not between LMS and STUMP (P >.05). Regarding the outcome of uterine LMS, patients with bcl-2 positive tumors showed less vascular space involvement and longer overall survival (P <.05).

CONCLUSION

Bcl-2 was expressed more frequently and more strongly in leiomyomas compared with LMS and STUMP. Regarding the outcome of uterine LMS, patients with bcl-2-positive tumors showed less vascular space involvement and longer overall survival. The stronger bcl-2 expression in benign leiomyomas and the better clinical outcome of bcl-2-positive LMS indicate that this protein seems to act as a good prognostic factor. Further studies including larger numbers of patients are necessary to establish bcl-2 as a routine marker for improved prognosis in malignant uterine smooth muscle tumors.

Leiomyoma originating from axilla: A rare case report and differential diagnosis

INTRODUCTION

Leiomyoma is a form of benign tumor originated in hypertrophy of the smooth muscles, which is most prevalent in the uterus and gastrointestinal tract. However, Leiomyoma originating from smooth muscle at the vessels lying on deep soft tissue is very rare.

CASE REPORT

Our case was a rare case of leiomyoma originating from the axillary region, which was initially diagnosed as a fibroadenoma on radiological examination. The mass was separated from surrounding tissues and totally resected. Pathologically, hematoxylin-eosin-stained biopsy tissue showed the typical findings of leiomyoma. Postoperative follow-up observation was done for 1 year, without any complications or recurrence.

CONCLUSION

Notably, a leiomyoma in the axillary region is difficult to differentiate from other benign or malignant tumors on preoperative radiological examinations such as ultrasonography or computed tomgraphy. Therefore, when an indefinite asymptomatic mass that is not lymphadenopathy or common benign tumor is identified in the axillary region, leiomyoma can be considered as one of the differential diagnoses.

Uterine Leiomyosarcoma Mimicking Benign Submucosal Leiomyoma

Uterine leiomyosarcoma is a rare, aggressive tumor of the smooth muscle with a typical intramural location. Patients present with abnormal uterine bleeding and an enlarged pelvic mass with clinical signs and symptoms that are virtually indistinguishable from benign leiomyoma. Sonographically, leiomyosarcoma presents as a large solitary tumor that closely resembles a benign leiomyoma that may be undergoing degenerative changes. Because of the infiltrative nature of leiomyosarcoma, invasion into the myometrium may be demonstrated. Leiomyosarcoma has a poor prognosis due to local pelvic recurrences and spread to distant sites. This case report demonstrates a fast-growing submucosal leiomyosarcoma with characteristic sonographic echo enhancement and infiltration into the myometrium.

Uterine Leiomyomas in Two Vietnamese Pot-bellied Pigs (Sus scrofa)

Two Vietnamese pot-bellied pigs ( Sus scrofa) were euthanatized after they developed abdominal distension. Necropsy of both pigs revealed large myometrial neoplasms and cystic endometrial hyperplasia. Multiple discrete smaller myometrial neoplasms were also observed in one pig; however, distant metastases were not observed in either animal. The tumors were diagnosed as leiomyomas on the basis of histologic examination and immunohistochemistry. This is the first detailed report of uterine leiomyomas in swine, and it is suggested that this diagnosis may become more common as more aging pigs are examined.

Massive Broad Ligament Cellular Leiomyoma with Cystic Change: A Diagnostic Dilemma

Leiomyomas are known to arise from uterus, but rarely from broad ligament. Further, cellular leiomyoma of broad ligament is the least common variant reported in literature. The diagnostic dilemma arises when leiomyomas undergo degenerative changes. This poses both clinical and radiological difficulty in differentiating with an ovarian tumour. We present an unusual case of a huge broad ligament mass measuring 29x19x09cm, mimicking an ovarian tumour both clinically and radiologically. Histopathology revealed cellular leiomyoma of broad ligament with cystic and myxoid degeneration hereby being the second case reported in literature. This case is being presented not only because of the rare incidence but also due to its diagnostic confusion with ovarian malignancy on clinical evaluation and radiological findings.

Histopathological and Digital Morphometrical Evaluation of Uterine Leiomyoma in Brazilian Women

The current study aims to evaluate histopathological and digital morphometrical aspects associated with uterine leiomyomas in one hundred and fifty (150) patients diagnosed with leiomyoma. Uterine tissues were subjected to the histopathological and digital morphometric analyses of the interstitial collagen distribution. The analysis of medical records indicates that most of the women diagnosed with uterine leiomyomas (68.7%) are between 37 and 48 years old. As for the anatomic location of the tumors, approximately 61.4% of the patients had intramural and subserosal lesions. In 50% of the studied cases, the patients developed uterine leiomyomatosis (with more than eight tumors). As for the morphometric study, the average size of the interstitial collagen distribution held approximately 28.53% of the capture area, whereas it was of 7.43% in the normal tissue adjacent to the tumor. Another important aspect observed in the current study was the high rate of young women subjected to total hysterectomy, a fact that resulted in early and definitive sterility.

Practical issues related to uterine pathology: endometrial stromal tumors

Uterine mesenchymal tumors continue to be a challenge to diagnose due to their non-specific clinical presentation, often non-distinctive gross appearance, varied (and many times overlapping) morphologic appearance, and unsuspected pitfalls in immunohistochemical expression. This review will focus on endometrial stromal tumors and those features that help in their distinction. In particular, a practical approach to the diagnosis of endometrial stromal neoplasia will be covered including recognition as a stromal process in a biopsy/curettage and distinction from a highly cellular leiomyoma. In addition, distinction of a stromal nodule from a low-grade endometrial stromal sarcoma (LGESS) and stromal sarcoma with limited infiltration in a hysterectomy specimen will be covered. The salient features that help distinguish a LGESS from a uterine tumor resembling ovarian sex-cord tumor as well as high-grade endometrial stromal sarcoma, the latter a tumor recently reintroduced in the WHO classification will also be discussed. Finally, a practical approach to the diagnosis of undifferentiated uterine sarcoma (UUS) will be presented.

Uterine cellular leiomyomata with chromosome 1p deletions represent a distinct entity

OBJECTIVE

This study aimed to determine whether 1p deletion defines a subset of cellular leiomyomata (CL), which is a hypercellular variant of uterine leiomyomata that may have delayed malignant potential, and to correlate this genetic change with clinical and pathologic characteristics including those present in uterine sarcomas.

STUDY DESIGN

Available CL cases at the Mayo Clinic (n = 101) and variant cases reported in another article (n = 16) were identified. Each case with sufficient tissue that met histologic criteria for CL when reviewed by a single pathologist underwent interphase fluorescence in situ hybridization to determine the presence of 1p deletion. Clinical characteristics of women with confirmed CL were compared on the basis of 1p deletion status using univariate analysis.

RESULTS

Of the Mayo Clinic cohort of histologically confirmed CL, 23% had deletion of 1p. Women with this subset of CL, when compared to those without 1p deletion, were more likely to be postmenopausal (P = .049) and their uteri tended to be heavier (P = .039) with a larger dominant leiomyoma (P = .030). The pathologic features associated with 1p deletion were high cellularity (P = .036) and hyaline necrosis (P = .047), which remained significant after inclusion of the CL cases from a previously published series.

CONCLUSION

Deletion of 1p occurs in approximately one-quarter of CL cases. This genetic alteration is potentially associated with clinicopathologic features that are present in uterine sarcomas, which suggests a distinct clinical entity that may have malignant potential. Our findings are particularly pertinent considering the increased preference for uterine-sparing options in leiomyoma treatment, suggesting assessment of 1p deletion status in CL may influence clinical surveillance decisions.

Estrogen and Progesterone Receptors Expression in Uterine Malignant Smooth Muscle Tumors: Correlation with Clinical Outcome

Uterine leiomyosarcomas are associated with a poor prognosis, although a considerable diversity in behavior may be found, and prolonged survival may occur. The aim of this study was to analyze the expression of estrogen (ER) and progesterone (PR) receptors in tumor specimens from uterine leiomyosarcomas, and to test their correlation with disease-free interval and cause-specific survival. This additional information may help the clinician differentiate between patients who have minimal risk of recurrence and those at greater risk of developing progressive disease. We examined specimens from 31 uterine leiomyosarcoma patients with clinical history and known follow-up. Disease-free interval and cause-specific survival rates were calculated according to the Kaplan-Meier method. According to univariate analysis, with Cox proportional hazards models, the ER expression (P=0.006 and P=0.016, respectively), PR expression (P=0.005 and P=0.016, respectively), and FIGO stage disease (P=0.011 and P=0.007, respectively) were independent predictors of the risk of recurrence and death from disease.

Clinical and pathological characteristics, pathological reevaluation and recurrence patterns of cellular leiomyomas: a retrospective study in 76 patients

OBJECTIVES

To analyze clinical and pathologic features as well as recurrence patterns of cellular leiomyomas (CL) in women who underwent surgical therapy for symptomatic disease.

STUDY DESIGN

This retrospective study was conducted at the Department of Obstetrics and Gynecology, University Women's Clinic, Tuebingen, Germany. We identified all women who had CL on final diagnosis after surgery between January 1, 2000, and December 31, 2010.

RESULTS

Our study sample comprised 76 women with a diagnosis of CL. A single uterine mass was present in 51.3% of the cases; in uteri with both CL and uterine leiomyomas (UL), the CL constituted the largest uterine mass in 20 of 21 (95.2%) cases. Additionally, in 98% of the uteri, CL were either the largest or the only uterine mass. Five women (6.6%; 5/76) had reported surgical procedures for symptomatic leiomyoma before the index surgery in our analysis. Three women underwent hysteroscopic resection of the leiomyomas and 2 women underwent abdominal myomectomy. Mean time to recurrence was 14.0 months (median 6.0; range, 4.0-52.0). Over the follow-up period, 6 women who underwent uterus-conserving surgery (12.0%; 6/50) with CL had leiomyoma recurrence. Five women underwent abdominal myomectomy and one underwent hysteroscopic resection of the CL. One patient had recurrence of a CL 43 months after abdominal myomectomy and underwent vaginal hysterectomy; the other five women had recurrences of UL. Mean time to recurrence was 28.6 months (median 12.5; range, 4.0-83.0).

CONCLUSIONS

Recurrence rates of CL in our study group resemble recurrence rates of UL.

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.

Differential Expression of IRS-1 and IRS-2 in Uterine Leiomyosarcomas with Distinct Oncogenic Phenotypes: Lack of Correlation with Downstream Signaling Events

Purpose: Insulin receptor substrates (IRSs) are essential for insulin-induced mitogenic effects on several cell types but they also are involved in cell transformation.We investigated whether the differential constitutive expression and potential distinct downstream signaling events of IRS-1 and IRS-2 might be related to discrete tumourigenic phenotypes of three human uterine leiomyosarcoma cell lines, one of which was specifically isolated for the present study.

Methods and results: SK-UT-1B egressed effectively from a gellyfied Matrigel matrix and grew as did DMR cells in an anchorage-independent manner in agar and induced rapidly growing tumours in nude mice. On the contrary, SK-LMS-1 cells did not emigrate from Matrigel, neither grew in agar nor were they tumourigenic. IRS-2 was highly expressed in the more malignant cell lines, whereas IRS-1 was present only in SK-LMS-1 cells. However, upon insulin stimulation both IRS- 1 and IRS-2 were tyrosine phosphorylated with a similar kinetic in the respective cell lines; furthermore, after 1 min of insulin stimulation PI3-kinase associated with IRSs and after 2 min Shc was phosphorylated and associated with Grb2 with minor differences detectable among the various cell lines in the duration of phosphorylation and/or in their association irrespective of whether IRS-1 or IRS-2 were expressed.

Discussion: Our findings tend to exclude that the malignancy displayed by uterine leiomyosarcomas might be directly linked to the activation of distinct IRS-1- or IRS-2-dependent pathways.

Understanding cellular leiomyomas: a case-control study

OBJECTIVE

Reports exist in which cellular leiomyomas (CLs) appear to have clinical characteristics or genetic profiles similar to leiomyosarcomas. This study aimed to determine whether most CLs differ clinically from typical uterine leiomyomas (ULs).

STUDY DESIGN

A case-control study was conducted with women who underwent surgical procedures between January 1989 and December 2008 and who were diagnosed with a CL (n = 99). Control subjects, who were matched in a 2:1 ratio, were women with a diagnosis of UL (n = 198). Hospital and ambulatory records were reviewed.

RESULTS

In multivariable logistic regression analyses, women with CLs were more likely to have surgery for the indication of enlarging leiomyoma and less likely to have concomitant endometriosis or adenomyosis. Uteri that contained CLs were also more likely to have larger and fewer leiomyomas when compared with control subjects.

CONCLUSION

CLs have a distinct clinical phenotype compared with ULs and have some characteristics in common with leiomyosarcomas.

Uterine smooth muscle tumors other than the ordinary leiomyomas and leiomyosarcomas: a review of selected variants with emphasis on recent advances and unusual morphology that may cause concern for malignancy

Uterine smooth muscle tumors are classified according to their morphologic features that include architecture, growth pattern, cellular characteristics and constituents of the intercellular stroma. While terminologies used for the pathologic diagnosis of various subtypes may be eloquent and histologically accurate, some of these are confusing for the clinician and may also be open to interpretation by different pathologists: the labeling of atypical leiomyomas epitomizes this intricate system. Clinically, it is probably more useful to classify them as either tumors with or tumors without recurrent and/or metastatic potential. The term "atypical leiomyoma" has been used to label tumors that have a low risk of recurrence and is synonymous with benign tumors. The latter are known variously as leiomyoma with bizarre nuclei, symplastic leiomyoma, or pleomorphic leiomyoma. Variants of benign uterine smooth muscle tumors, such as mitotically active leiomyoma, cellular and highly cellular leiomyoma, epithelioid leiomyoma, and myxoid leiomyoma each have distinctive hallmarks that enable subclassification. Nevertheless, they may occasionally possess one or more unusual features that are cause for alarm. Tumors that have a dissecting growth pattern, with or without extrauterine extension, may mimic malignancy both grossly and microscopically. The current review discusses the pathologic diagnosis of and terminology applied to selected variants of uterine smooth muscle tumors other than the ordinary leiomyomas and leiomyosarcomas with emphasis on unusual reported features that may indicate malignancy. This includes an update on uterine smooth muscle tumor of uncertain malignant potential (STUMP), intravenous leiomyomatosis, benign metastasizing leiomyoma, and diffuse leiomyomatosis. Their clinicopathologic features, differential diagnoses, and management options based on findings in the previously reported cases will also be reviewed.

Uterine smooth muscle tumors of uncertain malignant potential (STUMP): a clinicopathologic analysis of 16 cases

BACKGROUND

The current World Health Organization classification indicates that a uterine smooth muscle tumor that cannot be histologically diagnosed as unequivocally benign or malignant should be termed "smooth muscle tumor of uncertain malignant potential" (STUMP). STUMPs represent a heterogeneous group of rare tumors that have been the subject of only a few published studies, some of which lack detailed clinicopathologic details and/or follow-up data. More recently, it has been suggested that immunohistochemical staining may be helpful in the diagnosis of STUMPs.

DESIGN

The clinicopathologic features of 16 cases of STUMP that exhibited usual smooth muscle differentiation, diagnosed between 1992 and 2006 from 11 hospitals, were studied and classified into 4 subgroups using terminology and criteria described by Stanford investigators. Immunohistochemical stains for p16, p53, MIB1 (ki-67), and estrogen and progesterone receptors were performed. The results were compared with those in the literature.

RESULTS

The tumors were classified as follows: 6 as "atypical leiomyoma with limited experience", 7 as "smooth muscle tumor of low malignant potential", 2 as "atypical leiomyoma, low risk of recurrence," and 1 as "mitotically active leiomyoma, limited experience." Follow-up was 21 to 192 months (mean, 80.8 and median, 51.5). Only 2 tumors recurred, at 15 and 51 months, respectively; both were atypical leiomyoma with limited experience (multifocal moderate-to-severe atypia, no tumor cell necrosis, and mitotic counts of 4 and 5 mitotic figures /10 high-power fields, respectively). Both tumors had areas that were indistinguishable from benign leiomyoma and both had diffuse immunoreactivity for p16 and p53. Six other tumors that had focal staining for these markers all had a benign outcome. Both patients with recurrence were alive at last follow-up (at 40 and 74 mo). All the other patients were alive and disease-free.

CONCLUSIONS

This and other studies suggest that uterine tumors classified as STUMPs using criteria proposed by Stanford investigators are usually clinically benign but should be considered tumors of low malignant potential because they can occasionally recur, in some cases, years after hysterectomy. After a mean follow-up of 80.8 months, only 2 of 16 tumors in this study recurred. Both of the latter tumors fulfilled the criteria for atypical leiomyoma with limited experience. Notably, the 2 recurrent tumors were the only ones that were strongly immunoreactive for p16 and p53, supporting earlier observations that these markers may be helpful in the prediction of the behavior of STUMPs. Patients diagnosed with STUMPs should receive long-term surveillance.

Smooth muscle tumors of the uterus: a practical approach

Smooth muscle tumors (SMTs) are the most frequent mesenchymal tumors of the uterus. The majority of the uterine SMTs are readily classificable as benign or malignant based on their gross and microscopic appearances. However, when unusual features are seen in some leiomyoma variants, the differential diagnosis with a leiomyosarcoma may become challenging. Moreover, diagnostic criteria for the different subtypes of leiomyosarcoma are not uniform. Finally, non-smooth muscle tumors that originate in the uterus may show overlapping histologic and even immunohistochemical features with uterine SMTs, more commonly with the spindle and epithelioid variants, complicating their correct classification. The diagnosis of malignant uterine SMTs has important prognostic and therapeutic implications. This review provides a practical approach to the diagnosis of uterine leiomyosarcoma based on a systematic assessment of histologic parameters as well as a systematic approach to its differential diagnosis based on histologic and immunohistochemical features.

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.

Tranexamic Acid-associated Necrosis and Intralesional Thrombosis of Uterine Leiomyomas

INTRODUCTION

Women with menorrhagia have increased levels of plasminogen activators in the endometrium. Tranexamic acid (cyklokapron), an antifibrinolytic agent, is commonly prescribed worldwide to women with menorrhagia, including those with fibroids. Necrosis in uterine leiomyomas may be associated with pregnancy, and progestogen or oral contraceptive use but its association with tranexamic acid has not been investigated. Four hundred ninety patients with uterine leiomyomas in 2004 and 2005 were reviewed. Their ages ranged from 22 to 86 (mean 47.2). One hundred forty-seven (30%) were treated with tranexamic acid.

RESULTS

Infarct-type necrosis was observed in the leiomyomas of 38 patients, 22 of whom had tranexamic acid (15%) whereas the remaining 16 had no drug exposure (4.7%) (odds ratio=3.60; 95% confidence interval: 1.83-6.07; P=0.0003). Two patients who took the drug less than 2 weeks before surgery had early infarcts with appearance resembled coagulative type necrosis. Eleven of the 22 cases of drug-induced necrotic leiomyoma (50%) also showed intralesional thrombus formation, and 4 showed organization of the thrombi.

CONCLUSIONS

Infarct-type necrosis and thrombosis of leiomyoma was more commonly observed in patients treated with tranexamic acid. Although the drug is effective for menorrhagia, clinicians should be aware of the possible complications associated with leiomyoma necrosis such as pain and fever. Distinguishing between types of necrosis may not always be straightforward particularly in early infarcts when the reparative connective tissue reaction between the viable and necrotic cells is not well-developed, resulting in an appearance similar to coagulative necrosis. When the overall gross and microscopic features of a leiomyoma with coagulative necrosis favor a benign lesion, the drug history should be reviewed so that this type of early and healing infarct-type necrosis is considered as the underlying cause of the apparent coagulative necrosis. This may otherwise result in a diagnosis of smooth muscle tumor of uncertain malignant potential, leading to prolonged follow-up and unnecessary further surgical intervention.

Endometrial stromal tumours of the uterus: a practical approach using conventional morphology and ancillary techniques

Endometrial stromal tumours (ESTs) are diagnosed in most instances by light microscopy. Often, the greatest challenge is to distinguish between the different subtypes of these tumours. Furthermore, a handful of new or relatively new entities have been described in the literature, which may cause problems in the differential diagnosis; highly cellular leiomyoma is the most common. In addition, new antibodies have been developed to help in the distinction of ESTs from their mimics, as there are prognostic and therapeutic implications. A practical approach is provided for the diagnosis of ESTs on the basis of systematic assessment of histological and immunohistochemical parameters, and recent developments related to these tumours are highlighted.

Molecular Analysis of the JAZF1-JJAZ1 Gene Fusion by RT-PCR and Fluorescence In Situ Hybridization in Endometrial Stromal Neoplasms

Nonrandom cytogenetic abnormalities of chromosomes 6, 7, and 17 have been reported within low-grade endometrial stromal sarcomas (LGESSs), and among these abnormalities, the t(7;17)(p15;q21) is the most common aberration described. Previously we had shown that this translocation joins 2 genes, JAZF1 and JJAZ1, located on chromosomes 7 and 17, respectively. To determine the frequency of the t(7;17), we analyzed 4 stromal nodules and 24 LGESS by both reverse transcriptase-polymerase chain reaction and fluorescence in situ hybridization (FISH). In addition, we examined 4 cases of highly cellular leiomyoma, a benign morphologic mimic of LGESS. Overall, evidence for the JAZF1-JJAZ1 fusion was found in 60% of endometrial stromal neoplasms analyzed (8/16 ESS and 4/4 stromal nodules). One LGESS demonstrated only rearrangement of 7p15 by FISH analysis and karyotypic analysis of this case showed t(6;7)(p21;p15). The fusion was not detected in any highly cellular leiomyomas. Our data suggest that the JAZF1-JJAZ1 fusion is a frequent, although nonuniform, feature of endometrial stromal neoplasia, irrespective of benign versus malignant classification and smooth muscle differentiation. In addition, the detection of the fusion by reverse transcriptase-polymerase chain reaction or FISH for JJAZ1 at 7p15 may be diagnostically useful.

Uncommon sarcomas of the uterine cervix: a review of selected entities

Sarcomas constitute less than 1% of all cervical malignancies. With over 150 reported cases, rhabdomyosarcomas represent the most commonly reported sarcoma at this location. In this report, a select group of the more uncommon sarcomas of the uterine cervix are reviewed, including all previously reported examples of leiomyosarcoma, liposarcoma, alveolar soft part sarcoma, Ewing sarcoma/primitive neuroectodermal tumor, undifferentiated endocervical sarcoma, and malignant peripheral nerve sheath tumor (MPNST). Emphasis is placed on any distinctive clinicopathologic features of these entities at this unusual location.

Report of an unusual problematic uterine smooth muscle neoplasm, emphasizing the prognostic importance of coagulative tumor cell necrosis

Follow-up data of the clinical behavior of uterine smooth muscle tumors with low malignant potential are scarce. We present a woman suffering from a uterine smooth muscle cell tumor with increased cellularity, absence of significant atypia, and two to three mitotic figures per 10 HPFs but with minimal focal coagulative tumor cell necrosis (CTCN). These microscopic features are currently accepted to label the lesion as a "smooth muscle neoplasm of low malignant potential, limited experience." After a disease-free survival of 4 years, two retroperitoneal tumors around the iliac vessels were extirpated. Both tumors consisted of smooth muscle cells with mild to moderate atypia and a mitotic index of 5-10 per 10 HPFs but with multifocal and extensive CTCN. These microscopic features were sufficient to establish the diagnosis of leiomyosarcoma. This case adds to the limited experience of the clinical behavior of problematic uterine smooth muscle cell neoplasms and underscores the prognostic importance of CTCN.

Different subtypes of uterine sarcoma require a separate therapeutic approach

Uterine sarcomas include a variety of mono- and biphasic malignancies, whereas tumor biology varies from an indolent and hormone-sensitive growth pattern to an aggressive and nonresponsive disease that is inevitably fatal. Insight into these different entities has only been gained after careful analysis of clinical, pathologic and molecular characteristics during the last few years. Furthermore, the rarity of uterine sarcomas has motivated many to collect data from different subtypes and to report on the collective data in order to report on larger numbers. The current overview aims to provide insights of clinical importance into each type of uterine sarcoma, with a special emphasis on treatment modalities.

Ki-67 expression in patients with uterine leiomyomas, uterine smooth muscle tumors of uncertain malignant potential (STUMP) and uterine leiomyosarcomas (LMS)

BACKGROUND

The aim of the current study was to evaluate the expression of Ki-67 in uterine smooth muscle tumors, comparing leiomyomas, uterine smooth muscle tumors of uncertain malignant potential (STUMP) and uterine leiomyosarcomas (LMS) and to prove the accuracy of a Ki-67 expression as a useful parameter in the diagnosis of LMS.

METHODS

Ki-67 was assessed using immunohistochemistry from paraffin-embedded tissue in 20 patients with uterine LMS, 22 cases of STUMP and 25 cases of leiomyomas.

RESULTS

Ki-67 was present in 10/20 (50%) LMS, in 0/22 (0%) STUMP and in 2/25 (8%) leiomyomas. Significant differences regarding the frequency of Ki-67 expression were observed between LMS and STUMP (p = 0.0001) as well as between LMS and leiomyomas (p = 0.002), but not between STUMP and leiomyomas (p = 0.491). Likewise, the staining intensity differed significantly between LMS and leiomyomas (p = 0.018) as well as between LMS and STUMP (p = 0.002), but not between STUMP and leiomyomas (p = 0.368).

CONCLUSIONS

Our results demonstrate that the significantly elevated Ki-67 antigen expression in LMS, which correlates well with the rapid growth of these malignant tumors, may be a useful immunohistochemical parameter to distinguish between cases of malignant smooth muscle tumors and those of uncertain or borderline histology.

Expression of matrix metalloproteinases in patients with uterine smooth muscle tumors: an immunohistochemical analysis of MMP-1 and MMP-2 protein expression in leiomyoma, uterine smooth muscle tumor of uncertain malignant potential, and leiomyosarcoma

OBJECTIVE

Matrix metalloproteinases (MMPs) have been suggested to play an important role in tumor invasion and metastasis. We compared the expression of MMP-1 and MMP-2 protein in patients with leiomyoma, uterine smooth muscle tumor of uncertain malignant potential (STUMP), and leiomyosarcoma (LMS).

METHODS

MMP-1 and MMP-2 expression was investigated by immunohistochemistry from paraffin-embedded tissue in 26 patients with leiomyoma, in 24 patients with STUMP, and in 21 patients with LMS.

RESULTS

MMP-1 was expressed in 92% of leiomyomas, in 83% of STUMP, and in 86% of LMS, whereas MMP-2 was expressed in 12% of leiomyomas, in 17% of STUMP, and in 48% of LMS. A statistically significant difference regarding the frequency of MMP-2 expression was observed between LMS and STUMP (P =.025) as well as between LMS and leiomyoma (P =.006), but not between STUMP and leiomyoma (P >.05). Likewise, the staining intensity did significantly differ between LMS and leiomyoma (P =.025), but no statistical significant difference was observed between LMS and STUMP (P >.05) and between STUMP and leiomyoma (P >.05).

CONCLUSION

The stronger MMP-2 expression in patients with LMS compared with STUMP and leiomyoma indicates that this protein might be a marker for tumor invasion or metastasis in patients with uterine LMS. Furthermore, MMP-2 seems to be a useful immunohistochemical parameter to distinguish cases of smooth muscle tumors in which histologic features are ambiguous or borderline. Further studies including larger numbers of patients are necessary to establish MMP-2 as a routine marker for tumor invasion and progression.

Uterine smooth-muscle tumor of uncertain malignant potential metastasizing to the humerus as a high-grade leiomyosarcoma

BACKGROUND

Smooth-muscle tumors of uncertain malignant potential represent a variant of uterine leiomyoma and remain a dilemma due to their uncertain clinical behavior. Most of these tumors have a benign clinical course, and coagulative tumor cell necrosis has usually been associated with worse outcome.

CASE

We present a case of a uterine smooth-muscle tumor (SMT) of uncertain malignant potential without coagulative tumor cell necrosis that has metastasized to the humerus. The metastatic lesion was a high-grade leiomyosarcoma consistent with uterine origin.

CONCLUSIONS

Smooth-muscle tumors of uncertain malignant potential that demonstrate a lack of coagulative tumor cell necrosis do not necessarily insure benign clinical outcome. These lesions can recur and metastasize to distant sites, thus requiring long-term follow-up.