Uterine smooth muscle tumors of uncertain malignant potential (STUMP): a clinicopathologic analysis of 16 cases. Am J Surg Pathol. 2009;33:992-1005. [PMID: 19417585 DOI: 10.1097/pas.0b013e3181a02d1c]

Smooth Muscle Tumor of Uncertain Malignant Potential (STUMP): A Systematic Review of the Literature in the Last 20 Years

Smooth Muscle Tumor of Uncertain Malignant Potential (STUMP) is a rare uterine tumor primarily affecting perimenopausal and postmenopausal women, typically aged between 45 and 55 years. Characterized by ambiguous histological features, STUMPs present diagnostic challenges as they cannot be definitively classified as benign or malignant based on morphology alone. This systematic review aims to elucidate the clinical, pathological, immunohistochemical, and treatment-related characteristics of STUMPs through an analysis of the literature from the past 20 years. The study follows PRISMA guidelines, utilizing comprehensive searches of PubMed and Scopus databases, yielding 32 studies that meet the inclusion criteria. From the analysis of these studies, it was revealed that the clinical presentations vary from common symptoms such as abnormal uterine bleeding and pelvic pain to incidental detection of uterine mass. Histologically, STUMPs demonstrate features overlapping with both leiomyomas and leiomyosarcomas, including mild nuclear atypia, low mitotic indices, and focal necrosis. Immunohistochemical markers such as p16 and p53 have been investigated for prognostic significance. Elevated p16 expression, often associated with aggressive behavior, was observed in a subset of STUMPs. Surgical management, typically involving hysterectomy or tumorectomy, is the primary treatment, though the extent of resection is variable. Adjuvant therapies are not routinely recommended, but long-term surveillance is advised, especially for high-risk patients. Recurrence rates for STUMPs are approximately 12%, with factors such as high mitotic counts and coagulative necrosis indicating higher risk. This review highlights the complexity of STUMP diagnosis and management, emphasizing the need for more precise diagnostic criteria and individualized treatment strategies. Understanding the morphological, immunohistochemical, and clinical behavior of STUMPs can improve patient outcomes and guide future research in this diagnostically challenging area.

Clinicopathological Significance of Defective DNA Mismatch Repair in Endometrial Carcinoma: A Single-Center Study From Bahrain

INTRODUCTION

 Endometrial carcinoma, the most prevalent gynecologic malignancy in developed countries, represents a significant public health issue worldwide. DNA mismatch repair (dMMR) deficiency is an important molecular mechanism in endometrial carcinoma development, clinical course, and prognosis.

AIMS AND OBJECTIVES

 This study aimed to determine the incidence and histological subtypes of endometrial carcinoma among Bahraini women, evaluate the prevalence of MMR deficiency using immunohistochemistry in these patients and analyze the association between MMR deficiency and clinicopathological features, including potential links to Lynch syndrome.

PATIENTS AND METHODS

 This single-center retrospective study included 115 endometrial carcinoma patients diagnosed between January 2020 to June 2023. Immunohistochemistry was used to assess the expression of the four main MMR proteins (MLH1, MSH2, MSH6, PMS2). Clinicopathological features and survival outcomes were compared between MMR-deficient and MMR-proficient tumors. Medical records of patients were retrieved from I-SEHA system. Statistical analysis was done using SPSS.

RESULTS

 The study included a wide age range of patients, with a mean age of 59.5 years. The majority were Bahraini nationals. Endometrioid carcinoma was the most common histologic subtype (73%), followed by serous carcinoma (8.7%). Most patients presented with early-stage disease (76.8% stage I), and 39.8% had low-grade tumors. Significant proportions of cases showed loss of expression of mismatch repair (MMR) proteins MLH1 (24.2%), PMS2 (25%), MSH6 (14.5%), and MSH2 (12.7%), without significant associations with age.  Conclusion: This study found endometrial cancer to be a significant health concern in Bahrain, with a relatively high prevalence and younger age of onset compared to global averages. The data shows a predominance of endometrioid subtype and higher-grade tumors. Notably, a substantial proportion exhibited MMR deficiency, an important biomarker. These findings suggest the need for enhanced screening, early detection, and tailored treatment approaches in Bahrain. Further research and robust national cancer registries are warranted to fully understand the underlying risk factors and guide evidence-based interventions to mitigate the burden of this disease.

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.

Leiomyoma or sarcoma? MRI performance in the differential diagnosis of sonographically suspicious uterine masses

PURPOSE

To assess the diagnostic performance of MRI in distinguishing between leiomyomas and malignant/potentially malignant mesenchymal neoplasms in patients with rapidly enlarging/sonographically suspicious uterine masses.

METHODS

IRB-approved retrospective study including 88 patients (51 ± 11 years) who underwent MRI for rapidly enlarging/sonographically suspicious uterine mass at our Institution between January 2016 and December 2021, followed by surgery or >12 months follow-up. Qualitative image analysis was independently performed by 2 radiologists and included lesion's margins (sharp/irregular), architecture (homogeneous/inhomogeneous), presence of endometrial infiltration (yes/no), necrotic areas (yes/no), hemorrhagic areas (yes/no), predominant signal intensity on T1-WI, T2-WI, CE T1-WI, DWI, and ADC map. The same radiologists performed quantitative image analysis in consensus, which included lesion's maximum diameter, lesion/myometrium signal intensity ratio on T2-WI and CE T1-weighted images, lesion/endometrium signal intensity ratio on DWI and ADC map and necrosis percentage. Lesions were classified as benign or malignant. Imaging findings were compared with pathology and/or follow-up.

RESULTS

After surgery (52/88 patients) or follow-up (36/88 patients, 33 ± 20 months), 83/88 (94.3%) lesions were classified as benign and 5/88 (5.7%) as malignant/potentially malignant. Presence of necrotic areas, high necrosis percentage, hyperintensity on DWI and high lesion/endometrium DWI signal intensity ratio were significantly associated with malignant/potentially malignant lesions (p = 0.027, 0.002, 0.008 and 0.015, respectively). The two readers identified malignant/potentially malignant lesions with 95.5% accuracy, 80.0% sensitivity, 96.4% specificity, 57.1 % PPV, 93.3% NPV.

CONCLUSION

MRI has high accuracy in identifying malignant/potentially malignant myometrial masses. In everyday practice, however, MRI positive predictive value is relatively low given the low pre-test malignancy probability.

Low-Grade Uterine Leiomyosarcoma Is Highly Sensitive to Hormonal Treatment

PURPOSE

According to the World Health Organization classification system, uterine leiomyosarcomas (ULMS) are high-grade. A diagnosis of smooth-muscle tumors of uncertain malignant potential (STUMP) is made when Stanford Criteria for ULMS are not met. When a STUMP recurs, the tumor is diagnosed as ULMS and medical treatment is the same as for ULMS. In recent years, some sarcoma centers valued the less aggressive clinical behavior of several recurring STUMP and, given their expression of estrogen and progesterone receptors, started to treat them with hormonal therapy.

EXPERIMENTAL DESIGN

This was a retrospective cohort analysis conducted at three referral centers joining the Leiomyosarcoma Foundation Roundtable. We selected all cases of uterine smooth muscle tumors consistent with STUMP and treated with hormonal therapy.

RESULTS

27 consecutive patients were identified. Median age at diagnosis was 43 years. Stage was IA-IB in more than 70% of patients. In these patients, median time to relapse was 62 months. Sites of first relapses were mostly pelvis and peritoneum (76%). After a median follow-up of 49 months, 14 patients (52%) had a partial response while 10 (37%) had a minor response or stable disease. Median time to progression was not reached.

CONCLUSIONS

We observed a response or long-term stability rate on hormonal therapy in the 90% range; in all cases the time to relapse was significantly longer than in ULMS and in most cases the relapse was abdominal. On the basis of these findings, we conclude that a proportion of patients with uterine smooth muscle neoplasms actually present with a "low-grade ULMS."

Smooth Muscle Tumor of Uncertain Malignant Potential (STUMP): A Comprehensive Multidisciplinary Update

Background and Objectives: The uterine smooth muscle tumors of uncertain malignant potential (STUMP) are tumors with pathological characteristics similar to leiomyosarcoma, but that do not satisfy histological criteria for leiomyoma. These are problematic lesions with intermediate morphologic features; thus, diagnosis and treatment are difficult. This narrative review aims to review data in the literature about STUMPs, particularly focusing on management and therapeutic options and strategies for women who desire to preserve fertility. Material and Methods: authors searched for "uterine smooth muscle tumor of uncertain malignant potential" in PubMed and Scopus databases, from 2000 to March 2023. Pertinent articles were obtained in full-text format and screened for additional references. Only articles in English language were included. Studies including full case description of patients with histopathological diagnosis of STUMP in accordance with Stanford criteria were included. Results: The median age was 43 years old. Symptoms are similar to those of leiomyomas, with a mean diameter of 8.0 cm. Total hysterectomy with or without bilateral salpingo-oophorectomy is the standard care for women if fertility desire is satisfied. Myomectomy alone can be considered for young patients. Although these tumors have not a high malignant potential, several studies described recurrence and metastases. Conclusions: STUMPs are complex uterine smooth muscle tumors, with a rare but reasoned clinical-diagnostic management. Considering the high clinical and histological complexity of these tumors, high level of expertise is mandatory.

Uterine smooth muscle tumors with uncertain malignant potential: analysis following fertility-saving procedures

OBJECTIVE

The aim of this study was to analyze the clinical and reproductive outcomes of patients treated with myomectomy who were histologically diagnosed with uterine smooth muscle tumor of uncertain malignant potential (STUMP).

METHODS

Patients who were diagnosed with STUMP and underwent a myomectomy at our institution between October 2003 and October 2019 were identified. Variables of interest obtained from the institution's database included patient age, relevant medical history, pre-operative appearance of the tumor on ultrasound, parameters of the surgical procedure, histopathological analysis of the tumor, post-operative clinical course, and course of follow-up, including reinterventions and fertility outcomes.

RESULTS

There were a total of 46 patients that fulfilled the criteria of STUMP. The median patient age was 36 years (range, 18-48 years) and the mean follow-up was 47.6 months (range, 7-149 months). Thirty-four patients underwent primary laparoscopic procedures. Power morcellation was used for specimen extraction in 19 cases (55.9% of laparoscopic procedures). Endobag retrieval was used in nine patients and six procedures were converted to an open approach due to the suspicious peri-operative appearance of the tumor. Five patients underwent elective laparotomy due to the size and/or number of tumors; three patients had vaginal myomectomy; two patients had the tumor removed during planned cesarean section; and two underwent hysteroscopic resection.There were 13 reinterventions (five myomectomies and eight hysterectomies) with benign histology in 11 cases and STUMP histology in two cases (4.3% of all patients). We did not observe any recurrence as leiomyosarcoma or other uterine malignancy. We did not observe any deaths related to the diagnosis. Twenty-two pregnancies were recorded among 17 women, which resulted in 18 uncomplicated deliveries (17 by cesarean section and one vaginal), two missed abortions, and two pregnancy terminations.

CONCLUSIONS

Our study found that uterus-saving procedures and fertility-preservation strategies in women with STUMP are feasible, safe, and seem to be associated with a low risk of malignant recurrence, even while maintaining the mini-invasive laparoscopic approach.

MRI Evaluation of Uterine Masses for Risk of Leiomyosarcoma: A Consensus Statement

Laparoscopic myomectomy, a common gynecologic operation in premenopausal women, has become heavily regulated since 2014 following the dissemination of unsuspected uterine leiomyosarcoma (LMS) throughout the pelvis of a physician treated for symptomatic leiomyoma. Research since that time suggests a higher prevalence than previously suspected of uterine LMS in resected masses presumed to represent leiomyoma, as high as one in 770 women (0.13%). Though rare, the dissemination of an aggressive malignant neoplasm due to noncontained electromechanical morcellation in laparoscopic myomectomy is a devastating outcome. Gynecologic surgeons' desire for an evidence-based, noninvasive evaluation for LMS is driven by a clear need to avoid such harms while maintaining the availability of minimally invasive surgery for symptomatic leiomyoma. Laparoscopic gynecologists could rely upon the distinction of higher-risk uterine masses preoperatively to plan oncologic surgery (ie, potential hysterectomy) for patients with elevated risk for LMS and, conversely, to safely offer women with no or minimal indicators of elevated risk the fertility-preserving laparoscopic myomectomy. MRI evaluation for LMS may potentially serve this purpose in symptomatic women with leiomyomas. This evidence review and consensus statement defines imaging and disease-related terms to allow more uniform and reliable interpretation and identifies the highest priorities for future research on LMS evaluation.

Loss of dystrophin is common in uterine leiomyosarcoma: a potential biomarker for clinical application

Uterine leiomyosarcoma (LMS) is a deadly disease with high rates of recurrence and a poor prognosis. Its tumorigenesis remains largely unknown, and no specific biomarkers can be used for the differential diagnosis of LMS from other mimics. Recent whole-genome studies revealed a loss of dystrophin is common in LMS, especially in uterine LMS. To investigate the expression pattern of dystrophin expression across different types of uterine smooth muscle tumors, immunohistochemistry was performed, including usual-type leiomyoma, fumarate hydratase-deficient leiomyoma, leiomyoma with bizarre nuclei, conventional LMS, and normal myometrium for this study. To further evaluate the genomic change in dystrophin gene region, whole-genome sequencing in 10 LMS cases were analyzed. Dystrophin expression was detected in 94% (45/48) of myometrium, 97% (34/35) of usual-type leiomyoma, 84% (26/31) of fumarate hydratase-deficient leiomyoma, 60% (12/20) of leiomyoma with bizarre nuclei, and 18% (6/34) of LMS. Loss of dystrophin expression was significantly different between benign and malignant tumors (LMS cases counted as malignant only) (p < 0.01). Of note, copy number loss in the dystrophin genomic region was found in all 10 cases of LMS. Additionally, patients with dystrophin-positive LMS tend to have a better overall survival than patients with dystrophin-negative LMS.

Uterine Leiomyosarcoma Associated With Leiomyoma With Bizarre Nuclei: Histology and Genomic Analysis of 2 Cases

Leiomyoma with bizarre nuclei (LM-BN) is a rare variant of leiomyoma with overall benign clinical course. It has histologic features showing focal or diffuse nuclear atypia surrounded by usual type leiomyoma. Uterine leiomyosarcomas (LMS) are a group of rare and aggressive malignancies with limited treatment options available. The potential association between LM-BN with LMS is largely unknown. In this study, we report 2 cases of uterine smooth muscle tumor with typical histologic and molecular evidence of LM-BN, which are associated with its progression to the malignant counterpart of LMS. We summarize the detailed histologic, morphologic, and genomic characteristics of these 2 sets of cases. Our findings suggest that LMS progressing from preexisting LM-BN can be one of the tumor pathogenesis pathways in uterine leiomyosarcomas.

Data Set for Reporting of Uterine Malignant and Potentially Malignant Mesenchymal Tumors: Recommendations From the International Collaboration on Cancer Reporting (ICCR)

The International Collaboration on Cancer Reporting (ICCR) seeks to produce standardized, evidence-based protocols for the reporting of tumors with the aim of ensuring that all cancer reports generated worldwide will be of similar high quality and record the same elements. Herein, we describe the development of the data set for the reporting of uterine malignant and potentially malignant mesenchymal tumors by a panel of expert pathologists and a single clinician and provide the commentary and rationale for the inclusion of core and noncore elements. This data set, which incorporates the recent updates from the 5th edition of the World Health Organization Classification of Female Genital Tumors, addresses several subjects of debate including which mesenchymal tumors should be graded, how to document extent of invasion, mitotic counts, and the role of ancillary testing in tumor diagnosis and patient management. The inclusion of elements is evidence-based or based on consensus of the expert panel with clinical relevance being the guiding standard.

Acute abdomen with a parasitic smooth muscle tumor of uncertain malignant potential (STUMP) in pregnancy; a unique case report

INTRODUCTION AND IMPORTANCE

Diagnosis of a smooth muscle tumor of uncertain malignant potential (STUMP) during pregnancy is rare. Furthermore; the investigation of an intra-abdominal mass during pregnancy is clinically challenging due to anatomical changes and additional considerations of the developing fetus and radiation exposure. The unusual nature and diagnostic dilemma of such a case warrants a case report to serve as an educational prompt to clinicians who may encounter pregnant patients with undifferentiated intra-abdominal masses and/or suspecting of STUMP.

CASE PRESENTATION

We report a rare case of a parasitic STUMP diagnosed during pregnancy. The patient presented with a new umbilical hernia and deranged liver function tests (LFT's) during her third trimester. MRI reported a large mass in the left mid flank with intra-abdominal varices extending into the umbilical hernia. She went on to develop an acute abdomen requiring laparotomy where a parasitic fibroid adherent to the omentum was excised and a preterm infant was delivered via caesarean section. Histology was difficult due to pregnancy related changes but ultimately confirmed a diagnosis of STUMP.

CLINICAL DISCUSSION

STUMP in pregnancy is rare and diagnosis is further complicated by histological challenges due to pregnancy related changes. Postoperative diagnosis is challenging due to lack of universally accepted diagnostic criteria and Uncertainty regarding prognostic factors makes management and follow-up of patients with STUMP challenging. Studies have shown that younger patients are more likely to demonstrate recurrence.

CONCLUSION

Investigation and management of intra-abdominal masses in pregnancy is challenging. It requires timely multi-disciplinary team (MDT) input. Additional complications and considerations relate to the preterm fetus. Knowledge and understanding of these difficulties will better equip clinicians working with such patients to formulate a structured and well informed approach to the pregnant patient with a new intra-abdominal mass. Diagnosis of STUMP during pregnancy may be challenging for the pathologist and require further exert opinion.

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.

Clinical and Histopathological Predictors of Recurrence in Uterine Smooth Muscle Tumor of Uncertain Malignant Potential (STUMP): A Multicenter Retrospective Cohort Study of Tertiary Centers

BACKGROUND

The term uterine smooth muscle tumor of uncertain malignant potential (STUMP) indicates a rare, equivocal entity between benign leiomyomas and leiomyosarcomas. In the present study, we evaluated a comprehensive range of clinical, surgical, and pathological features in a large multicenter series of patients with STUMP to identify risk factors for recurrence.

METHODS

This is a retrospective study performed by collecting consecutive cases diagnosed between January 2000 and December 2020 in five tertiary centers. Associations between STUMP recurrence and clinicopathological characteristics as well as surgical treatment modality were investigated.

RESULTS

Eighty-seven patients affected by STUMP were considered. Of them, 18 cases (20.7%) recurred: 11 as leiomyosarcoma (LMS) and 7 as STUMP. The mean time to recurrence was 79 months. We found that fragmentation/morcellation, epithelioid features, high mitotic count, Ki-67 value > 20%, progesterone receptor (PR) < 83%, and p16 diffuse expression were associated with higher risk of recurrence and shorter recurrence-free survival (RFS). Furthermore, morcellation/fragmentation and mitotic count remained independent risk factors for recurrence and shorter RFS after multivariate analysis, while the presence of epithelioid features was an independent risk factor for recurrence only.

CONCLUSIONS

Our results suggest that morcellation is associated with risk of recurrence and shorter RFS, thus it should be avoided if a STUMP is suspected preoperatively. Epithelioid features, high proliferation activity, low PR expression, and diffuse p16 expression are also unfavorable prognostic factors, so patients presenting these features should be closely followed up.

Ultrasound features of highly vascularized uterine myomas (uterine smooth muscle tumors) and correlation with histopathology

OBJECTIVE

To correlate the ultrasound appearance of highly vascularized uterine myomas with their histopathological diagnosis.

METHODS

This was a prospective observational study of patients with a preoperative ultrasound diagnosis of a highly vascularized uterine myoma (color score of 3 or 4, according to the Morphological Uterus Sonographic Assessment (MUSA) criteria), characterized by circumferential and intralesional vascular pattern, who underwent myomectomy or hysterectomy. For each patient, ultrasound characteristics were recorded at baseline, including the number of lesions, the size, echogenicity and border regularity of the lesion, presence of cystic areas and shadowing within the myoma, and visualization of the endometrium. Ultrasound features were correlated with the definitive histological diagnosis. Ultrasound features were then compared between malignant and benign lesions.

RESULTS

We included 70 patients with highly vascularized uterine myomas on power/color Doppler. Their mean age was 46.5 ± 11.4 years and 13 (18.6%) were postmenopausal. At histological examination, 65 (92.9%) uterine myomas were benign lesions, comprising 32 typical leiomyomas, 29 leiomyoma variants and four adenomyomas. The remaining five (7.1%) uterine myomas were malignant masses, comprising two uterine sarcomas, one leiomyosarcoma, one neuroendocrine tumor and one uterine smooth muscle tumor of uncertain malignant potential (STUMP). The mean age of patients with a malignant lesion was significantly higher than the age of those with a benign lesion (64.8 ± 16.0 vs 42.4 ± 5.1; P < 0.001). Four out of five patients with a malignant lesion were over 45 years old. Ultrasound demonstrated cystic areas within the lesion in 10/32 (31.3%) typical leiomyomas, 16/29 (55.2%) leiomyoma variants, all four adenomyomas and in the cases of STUMP and leiomyosarcoma. Lesion borders were regular in 64/65 (98.5%) benign lesions and 2/5 (40%) malignant lesions (P < 0.05). No significant differences were observed between benign and malignant lesions with respect to echogenicity, presence of shadowing and size. The endometrium was visible in 55/65 women with benign lesions and in 2/5 with malignant lesions (P = 0.03).

CONCLUSIONS

Our results showed that ultrasound features of uterine myomas, such as circumferential and intralesional vascularity, cystic areas and lesion borders, are important parameters for differential diagnosis, especially when combined with the patient's age. Such features could be useful to differentiate typical myomas from benign variants and malignant lesions in a preoperative setting and to select patients that may benefit from conservative management rather than surgery. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Recurrence of Uterine Smooth Muscle Tumor of Uncertain Malignant Potential: A Systematic Review of the Literature

Background: This study aimed to systematically review the existing literature on uterine smooth muscle tumor of uncertain malignant potential (STUMP) to provide information about characteristics and outcomes of patients and the risk factors for recurrence over a period of 60 years (1960−2021). Methods: According to PRISMA guidelines, we searched for "uterine smooth muscle tumor of uncertain malignant potential" in PubMed (all fields) and Scopus (Title/Abstract/Keywords) databases (accessed on 1 January 2022). Relevant articles were obtained in full-text format and screened for additional references. The only filter used was the English language. Studies including full case description of patients with histopathological diagnosis of STUMP in accordance with Stanford criteria were included. Results: Thirty-four studies, including 189 cases, were included. The median age was 43 years, and in 21.5% of cases there was a recurrence of the disease. Bivariate analysis showed a significant association between use of morcellation without bag and risk of recurrence (p = 0.001). Unprotected morcellation during demolitive or conservative surgery was independently associated with a higher risk of disease recurrence with a relative risk of 2.94 (p < 0.001). A significant progressive decrease in the recurrence rate was observed over time (r = −0.671, p = 0.008). The percentage of patients who underwent surgery followed by in-bag protected morcellation significantly increased after the publication of the U.S. Food and Drug Administration alert about the risk linked to this procedure (p = 0.01). Conclusions: Unprotected morcellation of the lesion is associated with the relapse of the disease. However, this clinical condition showed a drastic decrease over time. This could likely be due to the increased awareness by surgeons of the importance of customizing surgical treatment.

Fumarate Hydratase Deficiency Should be Considered in the Differential Diagnosis of Uterine and Extrauterine Smooth Muscle Tumors of Uncertain Malignant Potential (STUMP)

Fumarate hydratase-deficient leiomyomas (dFH leiomyomas) often display atypical pathologic features yet exhibit a benign clinical course. Recent data suggest that dFH leiomyomas may be misclassified as smooth muscle tumors of uncertain malignant potential, a category that encompasses a heterogenous subgroup of uterine neoplasms with smooth muscle differentiation and atypical features that impart ambiguity regarding their expected clinical behavior. dFH leiomyomas can be seen in the context of hereditary leiomyomatosis and renal cell carcinoma syndrome or in the sporadic setting. In this retrospective study, we sought to examine the prevalence and clinicopathologic characteristics of dFH leiomyomas in 48 tumors previously diagnosed as smooth muscle tumors of uncertain malignant potential from 38 patients. Of these 48 tumors, 3 (6.3%) occurring in 2 patients were found to be deficient for FH by immunohistochemistry, including 1 uterine and 2 extrauterine (abdominopelvic) tumors. The 3 tumors showed histologic features typical of dFH leiomyomas, including hemangiopericytoma-like vessels, edema, macronucleoli, and atypia. Neither patient developed recurrent leiomyomas or renal cell carcinoma, and both were alive without disease at last follow-up. Our data suggest that dFH leiomyomas should be considered in the differential diagnosis of smooth muscle tumors of uncertain malignant potential, even in the context of extrauterine disease. Identification of FH deficiency in these tumors supports their classification as dFH leiomyomas despite their atypical morphologic features and/or clinical presentation. Importantly, detection of dFH in these cases may identify women at increased risk for hereditary leiomyomatosis and renal cell carcinoma who would benefit from genetic counseling and consideration for FH germline testing.

Intraparenchymal breast leiomyoma and atypical leiomyoma

Background

Breast leiomyoma is a rare benign mesenchymal tumor, accounting for less than 1% of all breast neoplasms. Cases of breast atypical leiomyoma is even more rarely reported and its diagnostic criteria together with its clinical courses is not cleared defined.

Case presentation

We described two patients with breast leiomyomas. One has unilateral benign breast leiomyoma, the other one has bilateral breast leiomyomas. For the bilateral case, the left-side tumor was diagnosed as benign leiomyoma while the right-side tumor was diagnosed as atypical leiomyoma. The morphological features that lead to the diagnosis of atypical leiomyoma are its invasive growth pattern, mild nuclear atypia, and mitotic figures up to 3mitoses/10HPF.

Conclusions

Atypical breast leiomyoma appears to behave like benign leiomyoma without recurrence in our study with nine-year follow-up. Due to the limited experience, cases presented as atypical intraparenchymal breast leiomyoma should be closely followed.

Infective Endocarditis Secondary to Bacteroides Thetaiotaomicron in a Patient With Uterine Smooth Muscle Tumor of Uncertain Malignant Potential: A Case Report and Review of the Literature

Bacteroides species are significant clinical pathogens with an associated mortality of more than 19% and are found in most anaerobic infections. Our report documents for the first time a case of infective endocarditis (IE) secondary to Bacteroides thetaiotaomicron (BT). We discuss the case of a 65-year-old female with a medical history of smooth muscle tumor of uncertain malignant potential (STUMP) who presented to the ED with lower quadrant pain. In the hospital, she was found to be in septic shock. A transthoracic echocardiogram showed large vegetation on the aortic valve with severe aortic regurgitation and a blood culture growing BT. We urge physicians to be alert to the fact that Gram-negative anaerobes like BT can cause IE.

Leiomyoma with nuclear atypia: Rare diseases that present a common diagnostic problem

Leiomyoma with nuclear atypia describes a group of uterine smooth muscle tumors with a wide range of histologic and clinical presentations and remarkable nuclear atypia. These include fumarate hydratase-deficient leiomyoma (FH-LM), intravenous leiomyomatosis (IV-LM), and leiomyoma with bizarre nuclei (LM-BN). Other uterine mesenchymal tumors, such as perivascular epithelioid tumor (PEComa) and inflammatory myofibroblastic tumors (IMFT) are the mimickers of leiomyoma with nuclear atypia. LM-BN is the primary tumor model with a long history in gynecologic pathology, but the histogenesis of LM-BN remains largely unknown. Differentiating LM-BN from other benign variants, tumors with uncertain malignant potential (STUMP), or fully malignant leiomyosarcoma (LMS) can be diagnostically challenging. Recent progress has improved the diagnosis of many types of leiomyoma with nuclear atypia based on their specific histology and molecular alterations. LM-BN is now a diagnosis of exclusion. In this article, I review the history of leiomyoma with nuclear atypia and compare the clinical, histologic, and molecular features of LM-BN with those of its mimics. In particular, I highlight the current progress made in molecular genetics and pitfalls in the diagnosis of different myogenic tumors with nuclear atypia.

A large and late mediastinal metastasis from a uterine smooth muscle tumour of uncertain malignant potential: A case report

INTRODUCTION

Smooth muscle tumours of uncertain malignant potential (STUMP) are mesenchymal uterine tumours with a malignant potential found somewhere between that of benign leiomyomas and leiomyosarcomas. Only three cases of STUMP pulmonary metastasis exist in the literature.

CASE PRESENTATION

We report the case of a 63 year-old female patient presenting with dysphonia secondary to recurrent laryngeal nerve paralysis due to an enormous mediastinal STUMP metastasis, 14 years after having undergone a total hysterectomy with bilateral salpingo-oophorectomy. A successful left pneumonectomy was performed and the mass weighing 1570 g was histologically confirmed as a STUMP metastasis.

DISCUSSION

Only three cases of pulmonary metastasis from STUMP have been reported in the recent literature and no robust information exists about the metastatic nature of STUMP. No cases exist in the literature of a successful pneumonectomy performed for a STUMP metastasis of such large dimensions presenting after many years from the diagnosis of the primary uterine lesion. Physicians should keep in mind that the finding of a smooth muscle tumour in the lung of a woman should promptly raise the suspicion of a metastatic uterine malignancy, even several years after diagnosis of the primary lesion.

CONCLUSION

Despite the size, invasiveness and late presentation of the STUMP metastasis, the surgery was successful and the patient no longer requires oxygen therapy.

Risk of Recurrence in Uterine Leiomyoma with Bizarre Nuclei: a Systematic Review and Meta-Analysis

Objective Leiomyoma with bizarre nuclei (LBN) is a variant of uterine leiomyoma, which has replaced the previous category of “atypical leiomyoma” and must be distinguished from smooth muscle tumors of uncertain malignant potential (STUMP). However, previously published series of “atypical leiomyoma” might have included both LBN and STUMP, due to the lack of strict diagnostic criteria. Based on such hypothesis, we aimed to define the risk of recurrence in LBN.

Study Design A systematic review and meta-analysis was performed by searching 4 electronic databases for all studies assessing the outcome of patients with “atypical leiomyoma” or LBN. The pooled absolute risk of recurrence was calculated. The included studies were subdivided into two subgroups based on the criteria used: “LBN + STUMP” or “LBN-only”.

Results Twelve studies with 433 patients were included. The pooled risk of recurrence was 5.5% overall. The funnel plot showed two cluster of studies which superimposed to the two subgroups. In the LBN + STUMP cluster/subgroup, the pooled risk of recurrence was 7.7%. In the LBN-only cluster/subgroup, the pooled risk of recurrence was 1.9%. Statistical heterogeneity was null in all analyses.

Conclusion Our results show a risk of recurrence of 1.9% for LBN; higher recurrence rates in older studies are likely due to the inclusion of STUMPs.

Rare Case of Smooth Muscle Tumor of Uncertain Malignant Potential - Clinical Case

Introduction: Smooth muscle tumor of uncertain malignant potential (STUMP) still represents a medical and surgical challenge, being rare and hard to diagnose. Normally STUMP consists in a multitude of uterine tumors that do not meet the current histologic criteria for a specific malignant or benign tumor. Clinical, imagistic and laboratory investigations seem to only raise the presumptive diagnosis in these cases, the diagnosis being confirmed during histological examination of the post hysterectomy/myomectomy specimen. Case report: We present the case of a 50-year-old female patient who was examined for the first time for pelvic pain and sensation of increased pressure in the lower abdomen in June 2020. A gynecology consultation was performed, during which a large uterine mass was felt on vaginal digital examination combined with pelvic palpation. Further pelvic ultrasound examination revealed a voluminous tumor of the left ovary. Then, a magnetic resonance imaging was performed, which showed a large pelvi-abdominal tumor of probable ovarian origin with a mixt tissue type and cystic structure, the presence of pathological abdominal and pelvic lymph nodes, ascites with a suspicion of peritoneal carcinomatosis. The patient was referred to a tertiary center and the multidisciplinary team recommended surgical treatment. A total hysterectomy with bilateral oophorectomy and stadial lymphadenectomy was performed. After surgery, the patient had a favorable evolution and was discharged five days after the intervention in a good health condition. Macroscopic and histological examinations of the biopsy pieces showed morphological aspects of uterine smooth muscles tumors with uncertain malignancy potential/STUMP and multiple uterine leiomyomas. Discussion:Due to the rarity of these tumors, the scientific literature needs to be constantly updated in order to help physicians to correctly identify and treat this pathology. It is highly recommended to identify tumors with a high malignancy potential, so that the follow up will be sufficient to discover and treat recurrences before they become life-threatening. Conclusion:Smooth muscle tumor of uncertain malignant potential remains a difficult diagnosis due to uncertainty between malignancy and benign features. Treatment approaches are difficult in these cases and must always be in accordance with the patients' desire to maintain their reproductive functions and fertility. Recurrence of STUMP has been reported, therefore a close follow up of these patients must always be performed.

p53, p16 and ki67 as immunohistochemical prognostic markers in uterine smooth muscle tumors of uncertain malignant potential (STUMP)

The risk stratification in gynecologic smooth muscle tumors of uncertain malignant potential (STUMP) is a crucial issue, but at present there are no validated prognostic markers. We aimed to assess p53, p16 and ki67 as immunohistochemical prognostic markers in STUMP through a systematic review and meta-analysis. Electronic databases were searched from their inception to July 2020. All studies assessing p53, p16 and/or ki67 immunohistochemistry in gynecologic STUMP series were included. Immunohistochemical patterns were categorized as "abnormal" vs "wild-type" for p53, "diffuse" vs "focal/negative" for p16, ≥ 10% vs 10% for ki67. The prognostic value for recurrence was assessed through Cox regression analysis; a p-value 0.05 was considered significant. Markers that resulted significant were assessed for prognostic accuracy with calculation of area under the curve (AUC) and post-test probability of recurrence. Seven studies with 171 patients were included. Significant association with disease-free survival was found for p53 (p 0.0001) and p16 (p 0.0001), but not for ki67 (p = 0.911). p53 showed sensitivity= 83%, specificity= 86%, AUC= 0.89, and post-test recurrence probabilities of 54% and 7% in the case of abnormal and wild-type expression, respectively. p16 showed sensitivity= 84%, specificity= 88%, AUC= 0.91 and post-test recurrence probabilities of 56% and 7% in the case of diffuse and focal/negative expression, respectively. In conclusion, p53 and p16 might be useful in the risk assessment of STUMP, despite not being suitable as stand-alone prognostic markers.

Uterine smooth muscle tumors of uncertain malignant potential (STUMP): A retrospective study in a single center

OBJECTIVE

Uterine smooth muscle tumors of uncertain malignant potential (STUMP) is a heterogeneous group of tumors with histological and biological diversity that cannot be defined as a benign leiomyoma or malignant leiomyosarcoma. The study aims to investigate the diagnostic methods, treatment management and prognosis of STUMP patients in a 13-year period.

STUDY DESIGN

We retrospectively reviewed the clinicopathologic information of 31 STUMP patients in Peking University People's Hospital. Statistical analyses were conducted to compare the difference of clinical characteristics between the women in myomectomy group and those in hysterectomy group.

RESULTS

The most common clinical presentation was menstrual disorder. The tumors were mainly manifested as hypoechoic, non-cystic nodules with low blood flow signal by pelvic doppler ultrasonography. Most tumors carried Ki-67 index ranging from 10% to 30%. Immunohistochemical markers such as ER, PR, p16 and Desmin was positively expressed in tumors. At the first operation, 21 cases underwent myomectomy and 10 cases underwent hysterectomy. The patients in myomectomy group were younger than those in hysterectomy group. In the follow-up period, two cases experienced a relapse in the form of STUMP within 36 months. One case died of cardiovascular accident while the other cases were alive. Six of 21 women in myomectomy group desired pregnancy and two healthy live births were recorded.

CONCLUSION

The diagnosis of STUMP primarily depends on histopathologic features. Fertility-sparing surgery may be a treatment selection for patients with fertility desire. Patients with STUMP, especially in the case of myomectomy, should be informed of recurrence risk and monitored closely.

Intraoperative Frozen Section Biopsy of Uterine Smooth Muscle Tumors: A Clinicopathologic Analysis of 112 Cases With Emphasis on Potential Diagnostic Pitfalls

Frozen sections of uterine smooth muscle tumors are infrequently required, and related diagnostic difficulties are seldom discussed. We analyzed the clinicopathologic features of 112 frozen sections of uterine smooth muscle tumors and determined the accuracy, reasons for deferrals, and causes of interpretational errors. Most patients (median age, 45 y) presented with pelvic mass symptoms (53%). The main reasons for a frozen section examination were an abnormal gross appearance including loss of the usual whorled pattern of leiomyoma (36 cases, 32.1%), and intraoperative discovery of an abnormal growth pattern and extrauterine extension of a uterine tumor (28 cases, 25%). There were 9 leiomyosarcomas and 103 leiomyomas, including 18 benign histologic variants. An accurate diagnosis of malignancy was achieved in all leiomyosarcomas, with the exception of a myxoid leiomyosarcoma. In 99 cases (88%), the frozen section diagnosis concurred with the permanent section diagnosis (false positives, 0.9%; false negatives, 0%). Misinterpretation of stromal hyalinization as tumor cell necrosis in a leiomyoma with amianthoid-like fibers was a major discrepancy. Two minor discrepancies did not lead to a change in management. The diagnosis was deferred in 10 cases (8.9%) because of stromal alterations, unusual cellular morphology, uncertain type of necrosis, and abnormal growth patterns. Thus, although various stromal and cellular alterations can cause diagnostic uncertainty, leading to deferrals, frozen section diagnosis of uterine smooth muscle tumors has a high accuracy rate. While a definitive frozen section diagnosis of malignancy may be made when there is unequivocal atypia, indisputable mitotic figures, and tumor cell necrosis, it is important to remember that nonmyogenic mesenchymal tumors may also mimic uterine smooth muscle tumors. In a frozen section setting, it would be sufficient to issue a diagnosis of "malignant mesenchymal tumor." For tumors that do not meet the criteria for malignancy, issuing a frozen section diagnosis of "atypical mesenchymal tumor and defer the histologic subtyping to the permanent sections" is appropriate.

Development of a Multi-Institutional Prediction Model for Three-Year Survival Status in Patients with Uterine Leiomyosarcoma (AGOG11-022/QCGC1302 Study)

Simple Summary

Uterine leiomyosarcoma is an aggressive tumor and the current staging system cannot differentiate the patients into different prognostic groups. This leads to difficulty in predicting the patients’ outcomes and planning for adjuvant therapy. We aimed to develop a prediction model that can predict the chance of survival by the third year. In this article, we had used different statistical tests to identify five readily available clinicopathologic parameters to build the prediction model. Internal validation was performed with satisfactory accuracy. Such a prediction model might help to predict survival outcome, and guide future research on the treatment modality.

Abstract

Background: The existing staging systems of uterine leiomyosarcoma (uLMS) cannot classify the patients into four non-overlapping prognostic groups. This study aimed to develop a prediction model to predict the three-year survival status of uLMS. Methods: In total, 201 patients with uLMS who had been treated between June 1993 and January 2014, were analyzed. Potential prognostic indicators were identified by univariate models followed by multivariate analyses. Prediction models were constructed by binomial regression with 3-year survival status as a binary outcome, and the final model was validated by internal cross-validation. Results: Nine potential parameters, including age, log tumor diameter, log mitotic count, cervical involvement, parametrial involvement, lymph node metastasis, distant metastasis, tumor circumscription and lymphovascular space invasion were identified. 110 patients had complete data to build the prediction models. Age, log tumor diameter, log mitotic count, distant metastasis, and circumscription were significantly correlated with the 3-year survival status. The final model with the lowest Akaike’s Information Criterion (117.56) was chosen and the cross validation estimated prediction accuracy was 0.745. Conclusion: We developed a prediction model for uLMS based on five readily available clinicopathologic parameters. This might provide a personalized prediction of the 3-year survival status and guide the use of adjuvant therapy, a cancer surveillance program, and future studies.

Clinical and reproductive outcomes of uterine smooth muscle tumor of uncertain malignant potential: a single-center retrospective study

OBJECTIVE

To evaluate the clinical outcomes, histopathological features, and obstetric and oncological outcomes of uterine smooth muscle tumor of uncertain malignant potential (STUMP).

METHODS

We conducted a single-center, database review of patients with STUMP between January 2001 and December 2015. We investigated the clinical, operative, histopathologic, recurrence, and fertility outcomes of the included cases.

RESULTS

Nineteen patients with STUMP were studied. Three were reclassified as sarcoma after slide review, and 16 patients were finally included in the study. The mean age was 45 years. Ki-67 expression was ≥10% in 25.0% of cases and 30% in the only recurrent case. Recurrence occurred 52 months after a diagnosis of STUMP in a 56-year-old female patient who underwent hysterectomy. Two of six patients who underwent myomectomy had fertility requirements, and both successfully delivered babies without recurrence. Recurrence was not related to mitosis, degree of atypia, or necrosis. There was also no relationship between type of surgery or surgical approach and recurrence.

CONCLUSIONS

Patients with STUMP warrant a pathological review process in centers with experience. Fertility-preservation is worth attempting, but young patients must be followed-up closely. Ki-67 might be a valuable marker predicting recurrence.

P16, Ki67, P53, and WT1 Expression in Uterine Smooth Muscle Tumors: An Adjunct in Confirming the Diagnosis of Malignancy in Ambiguous Cases

The diagnosis of uterine smooth muscle tumors is sometimes difficult, as these tumors may show worrisome features, suspicious for but not diagnostic of malignancy. The recommended immunohistochemical panel in this setting is currently under debate. In this study, we aimed to find a panel of immunohistochemical stains that would be helpful in determining the correct diagnosis in ambiguous uterine smooth muscle tumors, with an emphasis on investigating the possible usefulness of the WT1 antibody. Uterine leiomyomas were found to be immunoreactive with WT1. Since a previous study reported on the lack of immunoreactivity of uterine leiomyosarcomas with WT1, we speculated that WT1 might be useful in this setting. We retrospectively reviewed the medical charts and slides of 91 patients: 22 with leiomyosarcoma, 15 with smooth muscle tumor of uncertain malignant potential, and 54 with leiomyoma. Immunohistochemical stains for WT1, p16, p53, and Ki67 were performed on each case. We found that immunoreactivity with p16 and Ki67 (>40% and >10% of the tumor cells, respectively) and loss of nuclear expression of WT1 (<10% of the tumor cells) were significantly more common in leiomyosarcomas (all P<0.001). Mutated p53 immunohistochemical staining pattern was significantly more prevalent in leiomyosarcomas than in leiomyomas (P<0.001). Thus, in diagnostically challenging uterine smooth muscle tumors, we recommend using an immunohistochemical panel composed of Ki67, p16, p53, and WT1. A positive result in either of the former 2 (p16 >40% and/or Ki67 >10%) has the strongest association with leiomyosarcoma (sensitivity: 95.5%, specificity=88.9%, positive predictive value=77.8%, negative predictive value=98.0%).

Smooth Muscle Tumor of Uncertain Malignant Potential Arising from Renal Vein

Smooth muscle tumors (SMTs) typically fall under either benign leiomyoma or malignant leiomyosarcomas based on histologic characteristics. SMTs that cannot be diagnosed as benign or malignant are then labeled as smooth muscle tumors of uncertain malignant potential (STUMP). A 31-year-old male presented with the right abdominal pain for 6 months. Imaging showed an enhancing soft-tissue mass arising from the right renal vein. A pre-operative biopsy confirmed STUMP of renal vein, and the patient underwent surgical resection of the mass with partial nephrectomy. Imaging and pathologic findings play a crucial role in an accurate pre-procedural diagnosis of unusual SMTs.

An Emerging Anti-p16 Antibody-BC42 Clone as an Alternative to the Current E6H4 for Use in the Female Genital Tract Pathological Diagnosis: Our Experience and a Review on p16ink4a Functional Significance, Role in Daily-Practice Diagnosis, Prognostic Potential, and Technical Pitfalls

Background: To date, useful diagnostic applications of p16 IHC have been documented in gynecological pathology both for HPV-related and non-HPV-related lesions. In the present article, we reported our experience with the novel anti-p16 INK4a antibody (clone BC42), whose expression was tested across all different gynecologic neoplasms; we also compared it to the traditional E6H4 clone. Moreover, we discussed and explored all the diagnostic applications of p16 IHC in gynecologic pathology. Methods: Consultation cases covering a 5-year period (2016–2020) regarding gynecological neoplastic and non-neoplastic lesions in which immunohistochemistry for p16, clone E6H4 was originally performed, were retrospectively retrieved from the files of our institution. Immunohistochemical staining for p16ink4a (BC42) [Biocare Medical group-Paceco USA; Bioptica Milan] and p16ink4a (E6H4) [Ventana Medical Systems-Arizona USA; Roche] was performed by using the Ventana automated immunostainer (Ventana Medical Systems, Tucson, AZ, USA). The immunostaining pattern was defined as negative, focal/patchy, or diffuse. Results: A total of 196 cases, represented by 36 high-grade SIL/CIN3 of the uterine cervix, 30 cervical adenocarcinomas, 22 cervical squamous cell carcinoma, 70 endometrial carcinomas, 25 high grade serous ovarian carcinomas, 6 uterine adenomatoid tumors, and 10 uterine leiomyosarcomas were included in this study. Results showed concordant staining quality of both clones on all tested neoplastic tissues. Conclusions: The novel anti-p16 antibody (BC42 clone) appeared as an alternative to the current E6H4 for use in gynecological neoplasms, offering similar levels of positivity and equally reliable staining results.

Stanford parameters stratify the risk of recurrence in gynecologic smooth muscle tumors of uncertain malignant potential

Smooth muscle tumor of uncertain malignant potential (STUMP) is an ill-defined category of neoplasms, which represent a diagnostic challenge. We aimed to assess whether the Stanford parameters, that is, high mitotic index (≥10/10HPF), significant atypia (moderate-to-severe), and coagulative tumor cell necrosis (CTCN), even when focal or ambiguous, may be used to stratify the risk of recurrence in gynecological smooth muscle tumor of uncertain malignant potential (STUMP). Electronic databases were searched from their inception to October 2019. All studies assessing the Stanford parameters in gynecological STUMP series were included. STUMPs were subdivided according to the presence of the three Stanford parameters: high mitotic index, significant atypia, and CTCN. A Kaplan-Meier survival analysis was performed for recurrence-free survival; hazard ratio (HR) was calculated in each category. Fourteen studies with 219 STUMPs were included. In 15.5% of cases, none of the three Stanford parameters were present, with a recurrence risk of 5.9%; 2.7% of cases showed high mitotic index alone, with a recurrence risk of 0% (HR = not calculable); 43.8% of cases showed significant atypia alone, with a recurrence risk of 18.7% (HR = 3.3; p = 0.012); 26.5% of cases showed CTCN alone, with a recurrence risk of 17.2% (HR = 3.1; p = 0.029); and 11.4% of cases showed at least two Stanford parameters, with a recurrence risk of 32% (HR = 7.5; p = 0.003). Stanford parameters may stratify the risk of recurrence of STUMP. Significant atypia and CTCN, but not high mitotic index, may be stand-alone risk factors for recurrence in STUMP. The presence of at least two Stanford parameters, even if equivocal (e.g., uncertain or focal CTCN, focal significant atypia, mitotic index around 10/10HPF), might still be enough to support a diagnosis of leiomyosarcoma. Further studies are necessary in this field.

Genomic and Epigenomic Profile of Uterine Smooth Muscle Tumors of Uncertain Malignant Potential (STUMPs) Revealed Similarities and Differences with Leiomyomas and Leiomyosarcomas

Uterine smooth muscle tumors of uncertain malignant potential (STUMPs) represent a heterogeneous group of tumors that cannot be histologically diagnosed as unequivocally benign or malignant. For this reason, many authors are working to obtain a better definition of diagnostic and prognostic criteria. In this work, we analyzed the genomic and epigenomic profile of uterine smooth muscle tumors (USMTs) in order to find similarities and differences between STUMPs, leiomyosarcomas (LMSs) and leiomyomas (LMs), and possibly identify prognostic factors in this group of tumors. Array-CGH data on 23 USMTs demonstrated the presence of a more similar genomic profile between STUMPs and LMSs. Some genes, such as PRKDC and PUM2, with a potential prognostic value, were never previously associated with STUMP. The methylation data appears to be very promising, especially with regards to the divergent profile found in the sample that relapsed, characterized by an overall CGI hypomethylation. Finally, the Gene Ontology analysis highlighted some cancer genes that could play a pivotal role in the unexpected aggressive behavior that can be found in some of these tumors. These genes could prove to be prognostic markers in the future.

Prognostic significance of atypical mitotic figures in smooth muscle tumors of uncertain malignant potential (STUMP) of the uterus and uterine adnexa

We aimed to assess whether the presence of atypical mitotic figures (AMF) in smooth muscle tumors of uncertain malignant potential (STUMP) of the uterus and uterine adnexa is associated with increased risk of recurrence, and the association of AMF with the Stanford criteria, that is, significant cytologic atypia, mitotic index ≥ 10/10HPF, and coagulative tumor cell necrosis (CTCN). A systematic review was performed to identify all studies reporting the presence of AMF and oncologic outcomes in STUMP series. Fisher's exact test was used to assess the association of AMF with the three Stanford parameters. Kaplan-Meier and Cox regression survival analyses with hazard ratio (HR) calculation were performed to assess the association between AMF and STUMP recurrence. A p-value < 0.05 was considered significant. Five studies with 80 STUMPs were included, out of which 23.8% had AMF. AMF were significantly associated with the presence of significant atypia (p = 0.023), but not with the presence of a mitotic index ≥ 10/10HPF (p = 0.769), CTCN (p = 1), or more than one Stanford parameter (p = 0.171). AMF was not significantly associated with the risk of STUMP recurrence at both univariate (HR = 0.366; p = 0.188) and multivariate analyses (HR = 0.528; p = 0.463). In STUMP of the uterus and uterine adnexa, AMF are more common in the case of significant cytologic atypia, but do not seem to increase the risk of recurrence. Further studies are necessary in this regard.

[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 prognostication of uterine smooth muscle neoplasms: From CGH array to CINSARC signature and beyond

Uterine leiomyoma and leiomyosarcoma are located at the ends of the spectrum of smooth muscle lesions. Leiomyosarcoma belongs to the complex genomic sarcomas characterized by complex karyotypes. In contrast, leiomyoma, has a low level of chromosomal complexity. The analysis of genomic profiles of uterine smooth muscle tumors shows that genomic complexity, which is an expression of chromosomal instability, correlates with the metastatic potential and malignity of tumors: the more genetically complex a smooth muscle tumor is, the more malignant is its progression. In uterine tumors with uncertain malignant potential, the assessment of genomic index by CGH array, that is, counting the genomic complexity of a tumor, allows tumors with a risk of recurrence such as leiomyosarcomas to be distinguished from benign tumors like leiomyomas. The prognosis of leiomyosarcoma is poor and the most powerful prognostic factor so far is stage, as the histologic grade is not informative. In the quest to find efficient molecular prognostic factors, the transcriptomic signature CINSARC Nanocind, a mirror of chromosomic complexity and instability, outperforms stage, in both overall and recurrence-free survival. Genomic index and the CINSARC signature will contribute to improving diagnoses, therapeutic strategies, and randomization in future clinical trials. The biological understanding of the links between the CINSARC signature and metastatic mechanisms may lead to the development of new drugs. Furthermore, ctDNA is a promising new technique to detect residual disease and early recurrence.

Giant uterine mass with uterine smooth muscle tumor of uncertain malignant potential: A case report

•

STUMP is a rare disease histologically, and giant STUMP is extremely rare.

•

To our knowledge, present case represents the largest STUMP reported.

•

After successful surgery, the patient is alive without evidence of recurrence.

Background

Uterine smooth muscle tumor of uncertain malignant potential (STUMP) is a rare tumor belonging to a group of smooth muscle tumors that possess both benign and malignant features, complicating the diagnosis.

Case report.

We present the case of a 41-year-old primiparous woman who complained of heavy menstrual bleeding and severe pressure symptoms in the lower abdomen for 3 months. Magnetic resonance imaging revealed a large intramural myoma measuring 35 × 25 cm in the lower uterine corpus. A laparotomy including total hysterectomy was performed. Grossly, the uterine mass measured 38.5 × 35.4 × 20.4 cm in the largest diameter and weighed 18.3 kg. Pathological analysis revealed a uterine mass diagnosed as a smooth muscle tumor of uncertain malignant potential. The patient was normally discharged 7 days after surgery and decided to follow up without further treatment. At the time of this report, the patient had been followed up as an outpatient for 18 months without recurrence.

Conclusion

Giant uterine STUMP is extremely rare and difficult to diagnose on physical examination and imaging findings alone. It is important to consider the possibility of an underlying malignancy when performing a preoperative examination and to perform frozen biopsy if malignancy is suspected. During follow-up, patients should undergo consultation with a gynecologic oncologist and should be surveilled closely because of the possibility of recurrence or metastasis.

Uterine smooth muscle tumours of uncertain malignant potential: single-centre experience and review of the literature

Introduction

Uterine smooth muscle tumours of uncertain malignant potential (STUMPs) are a rare histologically heterogeneous group of uterine smooth muscle tumours (SMTs). Their malignant potential and clinical differentiation between leiomyoma and leiomyosarcoma remain uncertain prior to surgical removal.

Aim of the study

To investigate the patients and tumour characteristics of patients with STUMPs and to propose algorithms for optimal diagnosis, treatment, and follow-up management.

Material and methods

This was a single-centre retrospective cohort study of all patients who underwent surgery for a preoperative diagnosis of uterine myoma at the University Hospital “Dr. Georgi Stranski”, Pleven, Bulgaria during a period of 33 months (from January 2013 until October 2015). Data were obtained from the medical history records. We performed descriptive analysis to characterise the patient population (e.g. demographics, age, contraceptive use, and complaints that led to the diagnosis) and the tumour characteristics. Last data were obtained prior May 2019.

Results

A total of 320 medical records were retrospectively evaluated. The preoperative diagnosis of myoma was confirmed in 279 of the cases (89.4%). In 27 (8.3%) cases the final histological result was completely different. In 14 (2.3%) a histological postoperative diagnosis of STUMP was identified. All 14 STUMP lesions were intramural with a median size of 7.5 cm (range 3.5 to 15 cm). The median age at diagnosis of STUMP was 45.4 years (range 36 to 52 years), and 92.9% (n = 13) of the patients were premenopausal. Ultrasound data of a rapidly growing myoma were a reason for diagnosis in only three patients (25%), whereas 92.9% of the patients (n = 13) presented with heavy menstrual bleeding with or without anaemia. After surgery, none of the patients with STUMP experienced a relapse of the disease within the median follow-up time of 48 months (R = 40-78).

Conclusions

STUMP tumours are rare tumours, predominantly diagnosed in premenopausal women. They define a group of patients with very good long-term prognosis. Therefore, longer follow-up is needed to allow for conclusions on recurrence rate and survival.

Unexpected uterine smooth muscle tumor of uncertain malignant potential and sarcoma: A single center cohort study in South Korea

OBJECTIVE

To evaluate the risk of encountering unexpected uterine smooth muscle tumors of uncertain malignant potential (STUMPs) or sarcomas during surgical treatment of mesenchymal tumors of the uterus using morcellation.

MATERIAL AND METHODS

Data were collected retrospectively from subjects who were pathologically diagnosed with uterine leiomyoma or its variants, STUMP or other premalignant mesenchymal tumors of uterus, or sarcoma during surgical treatment between July 2014 and June 2017.

RESULTS

A total of 3785 women were investigated; 2824 laparoscopic procedures (74.6%) were performed, and an electronic power morcellator was used in 1636 patients (43.2%). Sixteen women (0.42%) were diagnosed with STUMP and 14 (0.37%) were diagnosed with uterine sarcoma. The incidence rate of unexpected STUMP or uterine sarcoma was 0.61% (23 of 3785 women); unexpected STUMP in 13 (0.34%), and unexpected sarcoma was in 10 (0.26%). Moreover, the unexpected leiomyosarcoma rate was 0.08% (3 in 3785). The rate of unintended morcellation of STUMPs was relatively high at 0.26% (10 in 3785), however, that for uterine sarcomas was 0.05% (2 in 3785).

CONCLUSION

The risks of unintended morcellation were very low for sarcomas and STUMPs, although the risk of the latter was approximately 5-fold that of the former. To reduce the unintended dissemination of tumors, patients suspected of having malignancies should be provided adequate information regarding their treatment options as well as their associated risks. Meanwhile, improved preoperative screening methods for STUMP and sarcoma should be established.

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.

Mass lesions of the myometrium: interpretation and management of unexpected pathology

PURPOSE OF REVIEW

Uterine leiomyomas are the most common benign uterine smooth muscle tumors. On the basis of imaging, these masses are often presumed to be benign conventional leiomyomas and surgical excision is a common treatment choice. After myomectomy or hysterectomy for presumed leiomyomas, the surgical pathology report may reveal an unexpected diagnosis of another type of mesenchymal tumor. These can range from a variant of benign smooth muscle tumors to smooth muscle tumors of uncertain malignant potential to malignant sarcomas. This review describes these variant pathologies and reviews data on recurrence risk and postoperative management.

RECENT FINDINGS

The majority of benign smooth muscle tumors will be classified as leiomyomas. Cellular, bizarre nuclei, mitotically active, epitheliod, myxoid, and dissecting are all terms that describe pathologic variants of benign leiomyomas. Smooth muscle tumors of uncertain malignant potential contain both benign and malignant features and should be referred to Gynecologic Oncology for follow-up. Leiomyosarcomas and low-grade endometrial stromal sarcomas may present preoperatively as benign tumors but are malignant with a high risk of recurrence and should be referred to Gynecologic Oncology.

SUMMARY

We advocate for the continued benefits of minimally invasive procedures in appropriately selected patients. Despite these measures, unexpected pathologic diagnoses can occur and should be managed appropriately.

How to differentiate uterine leiomyosarcoma from leiomyoma with imaging

Uterine leiomyomas, the most frequent benign myomatous tumors of the uterus, often cannot be distinguished from malignant uterine leiomyosarcomas using clinical criteria. Furthermore, imaging differentiation between both entities is frequently challenging due to their potential overlapping features. Because a suspected leiomyoma is often managed conservatively or with minimally invasive treatments, the misdiagnosis of leiomyosarcoma for a benign leiomyoma could potentially result in significant treatment delays, therefore increasing morbidity and mortality. In this review, we provide an overview of the differences between leiomyoma and leiomyosarcoma, mainly focusing on imaging characteristics, but also briefly touching upon their demographic, histopathological and clinical differences. The main indications and limitations of available cross-sectional imaging techniques are discussed, including ultrasound, computed tomography, magnetic resonance imaging (MRI) and positron emission tomography/computed tomography. A particular emphasis is placed on the review of specific MRI features that may allow distinction between leiomyomas and leiomyosarcomas according to the most recent evidence in the literature. The potential contribution of texture analysis is also discussed. In order to help guide-imaging diagnosis, we provide an MRI-based diagnostic algorithm which takes into account morphological and functional features, both individually and in combination, in an attempt to optimize radiologic differentiation of leiomyomas from leiomyosarcomas.

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.