IFITM1 Outperforms CD10 in Differentiating Low-grade Endometrial Stromal Sarcomas From Smooth Muscle Neoplasms of the Uterus

Uterine Smooth Muscle Tumors: An Overview

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

[Translocation-associated uterine mesenchymal tumors: The new without forgetting the old. An integrated diagnostic approach]

This review focuses on uterine mesenchymal tumors that are defined on a molecular level by a single and unique genetic alteration, that is somehow necessary and sufficient to allow tumor growth and progression. Although diverse from a clinical, morphological and immunohistochemical point of view, the different entities we are going to talk about share both a simple genomic profile with a low number of chromosomal alterations observed by CGH Array (few deletions, gains or amplifications...) and a low mutational burden observed by sequencing technics. Some of these entities are already well known and described in the literature when found outside of the uterus and gynecological tract. It remains intriguing that uterine mesenchymal pathology has been lagging behind when compared to its extrauterine counterpart. How can we explain that when it comes to inflammatory myofibroblastic tumors, abundant numbers of articles have been published since the 70's, but it was only in the early 2000s that the first relevant descriptions of this tumor in the uterus emerged? Certainly, the increased accuracy, availability, and use of molecular biology technics and in particular RNA sequencing in the area of uterine pathology can partly explain the reduction of the gap between soft tissue and uterine pathology we currently observe. Other reasons explaining this gap may be the high prevalence of smooth muscle tumors in the uterus and the abounding diversity of their morphological aspects, which may have partly eclipsed the array of differential diagnoses. Last but not least, one can hypothesize that the relative "simplicity" of hysterectomy procedures, referring to their safety and accessibility, has cured most of the lesions and partly clouded our knowledge regarding the biological potential and natural history of these newly described entities. As a consequence of this situation, our reader will often encounter the wording "uncertain malignant potential", as for some of these rare entities, evidence to establish reliable prognostic variables is still insufficient. We hope this review to be a useful tool to guide pathologists through the diversity and complexity of uterine mesenchymal tumors. As a scientific and medical community, sharing this knowledge will help us to collectively raise our vigilance and awareness by expanding the array of our differential diagnoses. We hope this will lead to more cases being accurately diagnosed, and ultimately, to a deeper knowledge regarding the biological potential and clinical evolution of these tumors. From a therapeutical point of view, the consequences of an accurate diagnosis for the patient are already appreciable through the use of targeted therapy. Examples include: ALK inhibitors in inflammatory myofibroblastic tumor, tyrosine-kinase inhibitors in COL1A::PDGFB rearranged sarcomas or mTOR inhibitors in PEComa.

Intravenous metastasis of unexpected uterine sarcoma in the context of uterine fibroids: case report and literature review

Objective

Endometrial stromal tumors are rare and complex mesenchymal tumors that often present with clinical symptoms similar to uterine leiomyomas. Due to their atypical nature, they are prone to be misdiagnosed or overlooked by healthcare professionals. This study presents a case report of an incidentally discovered endometrial stromal sarcoma with venous metastasis, which was initially misdiagnosed as a uterine leiomyoma. In addition, this study reviews previously documented cases of similar tumors.

Case report

During a routine medical examination in 2016, a 50-year-old woman was diagnosed with uterine fibroids. In June 2020, she began experiencing moderate, irregular vaginal bleeding. Nevertheless, a histopathological examination indicated an endometrial stromal sarcoma with a striking amalgamation of both low-grade and high-grade features. Molecular analysis identified a rare MED12 gene mutation. The patient underwent total hysterectomy, bilateral salpingectomy, and resection of the metastatic lesions. Postoperative management included radiotherapy, chemotherapy, and hormone therapy. After completion of chemotherapy, the patient was followed up for 27 months with no evidence of tumor recurrence.

Conclusion

This case report highlights the importance of pathological, immunohistochemical, and molecular aspects of this rare tumor involving the inferior vena cava and showing the presence of atypical gene mutations. The successful treatment outcome further emphasizes the importance of advances in diagnostic modalities for managing rare tumors like this.

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

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

Uterine Endometrial Stromal Tumors With Pure Low-Grade Morphology Harboring YWHAE::NUTM2 Fusions: Report of a Case Series Emphasizing Potential for High-Grade Transformation and Aggressive Behavior

Uterine endometrial stromal sarcomas (ESS) with YWHAE::NUTM2 gene fusions are typically morphologically high-grade tumors composed of atypical round cells, sometimes associated with a low-grade fibromyxoid component; they are currently included in the category of high-grade ESS (HGESS). We report 5 morphologically pure low-grade endometrial stromal tumors harboring YWHAE::NUTM2 fusions, including 1 endometrial stromal nodule (ESN) and 4 low-grade endometrial stromal sarcomas (LGESS), an association only occasionally reported previously. Patients ranged from 30 to 51 (mean=43) years and tumors from 4.5 to 7.5 cm (mean=5.7). All were stage I at diagnosis (confined to the uterus). Microscopically, the 4 LGESS showed extensive "tongue-like" invasion of the myometrium, and the ESN was entirely confined to the endometrium with no myometrial invasion. All tumors were composed entirely of morphologically uniform bland ovoid cells resembling proliferative endometrial stroma. A fibromyxoid component was seen in 1 LGESS and the ESN; in the LGESS, this was the sole component. Atypical round cells characteristic of YWHAE::NUTM2 HGESS were not identified. Mitotic count ranged from <1 to 13 per 10 high-power fields (mean: 3). CD10 was positive in 2/4 (focal), estrogen receptor in 5/5 (focal=1; diffuse=4), progesterone receptor in 5/5 (focal=1; diffuse=4) and cyclin D1 was diffusely positive in 3/4. Follow-up was available in all 5 patients and ranged from 6 to 159 months (mean=72). Two patients with LGESS had recurrent disease at 15 and 155 months; 1 showed predominantly LGESS with rare round cells in the initial recurrence and pure HGESS in a subsequent recurrence, while the other patient's recurrent tumor was predominantly HGESS (90%) in a background of focal fibromyxoid LGESS (10%). Both patients rapidly progressed and died of disease within 5 months of high-grade recurrence. We show that rare cases of morphologically pure low-grade endometrial stromal tumors, some but not all with a fibromyxoid component, harbor YWHAE::NUTM2 fusions and may recur rapidly, with transformation to HGESS and aggressive behavior. Our findings suggest that at least a subset of YWHAE::NUTM2 HGESS evolves from LGESS. We suggest that cyclin D1 and CD10 staining should be performed in all LGESS. Diffuse staining for cyclin D1 and/or negative or focal staining for CD10 should suggest the possibility of a YWHAE::NUTM2 fusion, and appropriate molecular testing should be undertaken. Since no single morphological or immunohistochemical parameter is entirely sensitive for fusion status, we also suggest that testing for a YWHAE::NUTM2 gene fusion should be considered in all cases of LGESS and, if a fusion is present, this should raise the possibility of subsequent high-grade transformation and aggressive behavior, even though such cases should still be categorized as LGESS. Although seemingly rare, ESN and LGESS with YWHAE::NUTM2 fusions may be under-recognized due to a lack of routine fusion testing.

NCOA1/2/3 rearrangements in uterine tumor resembling ovarian sex cord tumor: A clinicopathological and molecular study of 18 cases

Recurrent NCOA1/2/3 gene fusions emerged in uterine tumor resembling ovarian sex cord tumor (UTROSCT). More cases are required to consolidate these molecular alterations. In this study, the clinicopathological features and immunostaining profiles were reviewed in 18 UTROSCT. Fluorescence in situ hybridization for dual color break-apart probes of NCOA1, NCOA2, NCOA3, BCOR, YWHAE, PHF1 and JAZF1 were performed on 16 tumors. Eight cases were subjected to targeted next-generation sequencing to detect genomic alterations. We found that the tumors predominantly showed various sex-cord patterns without a recognizable endometrial stromal component. They exhibited a diverse immunohistochemical profile, frequently co-expressing sex cord (calretinin, inhibin, WT1, SF-1, and FOXL2), smooth muscle (SMA, desmin and caldesmon), epithelial (CK) and other markers (CD10 and IFITM1). Fourteen of 16 tumors (87.5%) showed NCOA1-3 gene rearranges, but none had BCOR, YWHAE, PHF1 and JAZF1 fusions. Five tumors contained 6 non-recurrent pathogenic (likely) mutations and one had gains in c-MYC. Our study supports frequent NCOA1-3 rearrangements in UTROSCT. Rare, non-recurrent mutations suggest that these gene rearrangements be potential drivers in tumorigenesis. Detection of gene rearrangements can contribute to the correct interpretation of UTROSCT. However, large comparative studies with molecular tests are required to confirm these findings.

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

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

[Endometrial and other rare uterine sarcomas : Diagnostic aspects in the context of the 2020 WHO classification]

Uterine sarcomas are a heterogeneous group of rare malignancies. Mostly (40-50%), they are leiomyosarcomas, followed by endometrial stromal sarcomas (ESS), low-grade (LG) and high-grade (HG), as well as undifferentiated sarcoma of the uterus (UUS) and adenosarcomas (AS). Other, non-organ-specific tumours such as NTRK-rearranged spindle cell neoplasia, perivascular epithelioid cell tumour (PEComa) and inflammatory myofibroblastic tumour (IMT) are extremely difficult to differentiate.In the most recent WHO classification, endometrial stromal tumours are subdivided as follows: benign, expansively growing endometrial stromal nodule (ESN) with sharp demarcation, the histologically similar-looking LG-ESS with infiltrative growth, the highly malignant HG-ESS and, as a diagnosis of exclusion, the highly aggressive UUS lacking specific lines of differentiation. LG-ESS can be differentiated from HG-ESS in most cases histomorphologically and immunohistochemically, but molecular investigations are necessary in individual cases. HG-ESS can be divided into 4 subtypes (YWHAE/NUTM2 fusion low-grade component, YWHAE/NUTM2 fusion high-grade component, ZC3H7B-BCOR fusion or BCOR-ITD) on the basis of molecular findings. Prognostically unfavourable factors in AS are severe sarcomatous overgrowth, deep myometrial invasion, high-grade histology and lymphatic vessel invasion. Tumours with NTRK fusion are immunohistochemically positive for S100 and TRK. PEComas express cathepsin K and HMB45, as well as TFE3 when translocation is present. Almost every IMT shows an alteration in the ALK gene In the case of overlapping morphology and simultaneous therapeutic and prognostic relevance, it is becoming increasingly important to verify or confirm the suspected histomorphological diagnosis by immunohistochemical and possibly molecular investigations.

A difficult to diagnose case of low-grade endometrial stromal sarcoma with smooth muscle differentiation treated with laparoscopic surgery: A case report

Low-grade endometrial stromal sarcoma (LGESS) is a rare uterine tumor, accounting for <1% of all uterine cancer cases. LGESS has several variations and the frequency of tumors exhibiting smooth muscle differentiation is 10-30% of LGESS cases, making such cases even rarer. The present report described the case of a patient with LGESS with smooth muscle differentiation, who was diagnosed as having uterine leiomyoma by preoperative needle biopsy and then underwent laparoscopic surgery. The patient was a 41-year-old woman. MRI findings revealed a diffusely hyperintense uterine tumor on T2-weighted images, thus needle biopsy was performed. This tumor was initially diagnosed as leiomyoma, due to the pathological findings of the biopsied specimen, which possessed tumor cells with spindle-shaped nuclei arranged in a cord and positive immunostaining for smooth muscle actin. The patient was subsequently followed up, and MRI findings after 29 months showed tumor growth. Needle biopsy was performed again and the findings were the same as those of the first biopsy; therefore, this tumor was diagnosed as a leiomyoma and laparoscopic hysterectomy was performed. However, the pathological findings of the excised uterus showed small round tumor cells and CD10 immunostaining positivity, thus the tumor was finally diagnosed as LGESS. The patient requested to be followed up and has shown no signs of recurrence 20 months after surgery. The results of retrospective examination in this case suggested that the presence of regions where only CD10 was positive in immunostaining analysis for SMA and CD10 was useful for needle biopsy diagnosis of LGESS with smooth muscle differentiation.

Role of the Immunohistochemical ZEB1 Expression in Uterine Mesenchymal Neoplasms

The distinction of mesenchymal tumors of the uterus is a frequent diagnostic challenge in gynecologic pathology. Especially, distinguishing low-grade endometrial stromal sarcoma (ESS) from leiomyoma or distinguishing low-grade ESS from high-grade ESS can be difficult. Epithelial-mesenchymal transition (EMT) is a physiological and pathological process in which epithelial cells lose their morphological features, become elongated and acquire mesenchymal traits. The signaling pathway of Zinc finger E-box binding homeobox 1 (ZEB1) is one of the most significant pathways involved in the EMT process and it has a crucial role in cancer progression, metastasis, and therapy resistance. We studied a series of 69 uterine mesenchymal neoplasms including 18 endometrial stromal sarcomas (10 cases of low grade and 8 cases of high grade endometrial stromal sarcomas), 26 leiomyosarcomas (8 cases of grade 1 and 19 cases of grade 2-3 leiomyosarcomas), 15 leiomyomas, and 10 rhabdomyosarcomas, using an antibody ZEB1. We graded the leiomyosarcomas depending on the FNCLCC grading system. It was observed that leiomyosarcoma was more intensely stained with ZEB1 than leiomyoma (P < 0.001) and high-grade ESS was significantly more intensely stained with ZEB1 protein than low-grade ESS (P < 0.004). It also was observed that high-grade leiomyosarcoma was significantly more intensely stained with ZEB1 protein than low-grade leiomyosarcoma (P < 0.000). Our data suggest that Zeb1 can be used to differentiate high-grade sarcomas from their low-grade counterparts as well as benign and malignant smooth muscle tumors of the uterus.

Uterine cellular leiomyomas are characterized by common HMGA2 aberrations, followed by chromosome 1p deletion and MED12 mutation: morphological, molecular, and immunohistochemical study of 52 cases

Cellular leiomyoma (CL) represents an uncommon variant of uterine leiomyoma with limited data concerning its immunohistochemical and molecular profile. We performed a comprehensive analysis of 52 CL cases all of which were analyzed immunohistochemically. Molecular analysis was possible in 32 cases with sufficient DNA, and 38 cases with sufficient RNA. The immunohistochemical results showed a high expression of smooth muscle markers (calponin (100%), desmin (100%), smooth muscle actin (98.1%), caldesmon (96.1%), transgelin (96.1%), smooth muscle myosin heavy chain (86.5%), and smoothelin (61.5%)). Concerning markers of endometrial stromal differentiation, the expression of CD10 was observed in 65.4% cases (42.2% with H-score > 50), and IFITM1 in 36.5% cases (1.9% with H-score > 50). 36.5% showed HMGA2 overexpression at the IHC level, associated with increased mRNA expression in 14/14 cases. The rearrangement of the HMGA2 gene was detected in 13.2%. Chromosome 1p deletion was found in 19.3%, while 9.4% of tumors showed a pathogenic mutation in the MED12 gene. In conclusion, CL is immunohistochemically characterized by a high expression of "smooth muscle" markers commonly associated with a co-expression of "endometrial stromal" markers, where IFITM1 shows superior performance compared to CD10 regarding its specificity for differentiation from endometrial stromal tumors. The sensitivity of smoothelin in CL seems rather low, but no data is available to assess its specificity. On a molecular level, the most common mutually exclusive aberration in CL affects HMGA2, followed by chromosome 1p deletions and MED12 mutations.

IFITM1, CD10, SMA, and h-caldesmon as a helpful combination in differential diagnosis between endometrial stromal tumor and cellular leiomyoma

Background

The differential diagnosis of endometrial stromal tumor (EST) and uterine cellular leiomyoma (CL) remains a challenge in clinical practice, especially low grade endometrial stromal sarcoma (ESS) and CL, suggesting the need for novel immunomarkers panels for differential diagnosis. Interferon-induced transmembrane protein 1 (IFITM1) is a novel immunomarker for endometrial stromal cells, h-caldesmon is an immunomarker for smooth muscle cells and has a higher specificity than smooth muscle actin (SMA). So this study aimed to evaluate whether IFITM1, cluster of differentiation 10(CD10), SMA, and h-caldesmon are useful biomarker combinations for the differential diagnosis of EST and CL.

Methods

Tissue microarrays were used to detect IFITM1, CD10, SMA, and h-caldesmon immunohistochemical staining in 30 EST and 33 CL cases.

Results

The expressions of IFITM1 and CD10 were high in EST (86.7 and 63.3%, respectively) but low in CL (18.2 and 21.2%), whereas those of h-caldesmon and SMA were high in CL (87.9 and 100%) and low in EST (6.9 and 40%). In diagnosing EST, IFITM1 shows better sensitivity and specificity (86.7 and 81.8%, respectively) than CD10 (63.3 and 78.8%). The specificity of h-caldesmon in diagnosing CL was significantly higher (93.1%) than that of SMA (60%). When all four antibodies were combined for the differential diagnosis, the area-under-the-curve (AUC) predictive value was 0.995. The best combination for diagnosing EST was IFITM1 (+) or CD10 (+) and h-caldesmon (−) (sensitivity 86.7%, specificity 93.9%).

Conclusion

The best combination for diagnosing CL were h-caldesmon (+) and SMA (+) (sensitivity 87.9%, specificity 100%). IFITM1, CD10, SMA, and h-caldesmon are a good combination for the differential diagnosis of EST and CL.

Vaginal Low-Grade Endometrial Stromal Sarcoma: An Extremely Rare Case Report and Review of the Literature

Endometrial stromal sarcoma (ESS) is a malignant tumor of the uterus that has been described as the second most common malignant uterine mesenchymal tumor. Primary extrauterine ESS (EESS) is an extremely uncommon occurrence. We hereby report a new bona fide case of low-grade EESS in a 74-yr-old woman arising in the vagina, presenting as a polypoid mass associated with irregular vaginal bleeding. On examination, a 6×2×2 cm polypoid mass was found in the left vaginal wall. Consequently, the patient underwent partial vaginectomy and repair. No ESS or endometriotic lesion was found in the endometrium and bilateral adnexa. The diagnosis of ESS performed by typical pathologic and immunohistochemical evaluation was as follows: beta-catenin (+++), estrogen receptor (+++), progesterone receptor (++), vimentin (++), and uniformly negative for CD10, EMA, CD31, CD34, CD117,CD99, SMA, desmin, h-caldesmon, S-100, MelanA, and HMB45. She has remained disease free with no signs or symptoms of recurrent or advanced disease for 46 mo. Although CD10 is the most useful immunohistochemical marker for the diagnosis of this tumor, negative CD10 staining can be encountered with underfixation. Therefore, it is important to use a panel of immunostains that includes CD10, beta-catenin, and smooth muscle markers. The present study describes the clinical and pathologic features of low-grade EESS through a case report and literature review. To the best of our knowledge, this is the eighth report of EESS arising from the vagina.

Update on Endometrial Stromal Tumours of the Uterus

Endometrial stromal tumours (ESTs) are rare, intriguing uterine mesenchymal neoplasms with variegated histopathological, immunohistochemical and molecular characteristics. Morphologically, ESTs resemble endometrial stromal cells in the proliferative phase of the menstrual cycle. In 1966 Norris and Taylor classified ESTs into benign and malignant categories according to the mitotic count. In the most recent classification by the WHO (2020), ESTs have been divided into four categories: Endometrial Stromal Nodules (ESNs), Low-Grade Endometrial Stromal Sarcomas (LG-ESSs), High-Grade Endometrial Stromal Sarcomas (HG-ESSs) and Undifferentiated Uterine Sarcomas (UUSs). ESNs are clinically benign. LG-ESSs are tumours of low malignant potential, often with indolent clinical behaviour, with some cases presented with a late recurrence after hysterectomy. HG-ESSs are tumours of high malignant potential with more aggressive clinical outcome. UUSs show high-grade morphological features with very aggressive clinical behavior. With the advent of molecular techniques, the morphological classification of ESTs can be integrated with molecular findings in enhanced classification of these tumours. In the future, the morphological and immunohistochemical features correlated with molecular categorisation of ESTs, will become a robust means to plan therapeutic decisions, especially in recurrences and metastatic disease. In this review, we summarise the morphological, immunohistochemical and molecular features of ESTs with particular reference to the most recent molecular findings.

[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.

IFITM1 is a Novel, Highly Sensitive Marker for Endometriotic Stromal Cells in Ovarian and Extragenital Endometriosis

When the presence of endometriotic lesions are not evident by hematoxylin and eosin staining, CD10 is used to highlight and confirm the presence of endometriotic stroma. However, CD10 is not specific only to the endometrial stroma but is also expressed in many other cells. Recently, interferon-inducible transmembrane protein 1 (IFITM1) was reported as a highly specific immunohistochemical marker of normal endometrial stroma and endometrial stromal neoplasm. In this study, we examined the expression of IFITM1 and CD10 in 18 cases of ovarian endometriosis and 44 cases of extragenital endometriosis. Among the 62 patients, 62 (100.0%) were positive for IFITM1 and 60 (96.8%) for CD10, and CD10 was negative in 2 cases that were positive for IFITM1. Additionally, we found that IFITM1 sensitivity was unaffected by the presence or absence of hormonal therapy. To the best of our knowledge, this represents the first demonstration of IFITM1 as a highly sensitive stromal marker of ovarian and extragenital endometriosis.

A Comprehensive Review of Biomarker Use in the Gynecologic Tract Including Differential Diagnoses and Diagnostic Pitfalls

Morphologic (ie, hematoxylin and eosin) evaluation of the Mullerian tract remains the gold standard for diagnostic evaluation; nevertheless, ancillary/biomarker studies are increasingly utilized in daily practice to assist in the subclassification of gynecologic lesions and tumors. The most frequently utilized "biomarker" technique is immunohistochemistry; however, in situ hybridization (chromogenic and fluorescence), chromosomal evaluation, and molecular analysis can also be utilized to aid in diagnosis. This review focuses on the use of immunohistochemistry in the Mullerian tract, and discusses common antibody panels, sensitivity and specificity of specific antibodies, and points out potential diagnostic pitfalls when using such antibodies.

IFITM1 is a Novel, Highly Sensitive Marker for Endometriotic Stromal Cells in Ovarian and Extragenital Endometriosis

When the presence of endometriotic lesions are not evident by hematoxylin and eosin staining, CD10 is used to highlight and confirm the presence of endometriotic stroma. However, CD10 is not specific only to the endometrial stroma but is also expressed in many other cells. Recently, interferon-inducible transmembrane protein 1 (IFITM1) was reported as a highly specific immunohistochemical marker of normal endometrial stroma and endometrial stromal neoplasm. In this study, we examined the expression of IFITM1 and CD10 in 18 cases of ovarian endometriosis and 44 cases of extragenital endometriosis. Among the 62 patients, 62 (100.0%) were positive for IFITM1 and 60 (96.8%) for CD10, and CD10 was negative in 2 cases that were positive for IFITM1. Additionally, we found that IFITM1 sensitivity was unaffected by the presence or absence of hormonal therapy. To the best of our knowledge, this represents the first demonstration of IFITM1 as a highly sensitive stromal marker of ovarian and extragenital endometriosis.