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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. [ABSTRACT FROM AUTHOR]

Smooth muscle tumors of unknown malignant potential (STUMP) represent a group of heterogeneous uterine neoplasms showing worrisome histological features, raising concerns for a malignant behavior, but do not satisfy the diagnostic criteria for leiomyosarcoma. The existing literature remains scarce due to its rarity; therefore, there is no consensus regarding diagnostic criteria, malignant potential, treatment of choice, and follow-up. The authors report their case series to analyze the heterogeneous features of this poorly understood neoplasm. A retrospective, monocentric cohort study of all patients who underwent surgery diagnosed with STUMP at the Garibaldi-Nesima Hospital in Catania from February 2018 to August 2021 was conducted. Each patient's age at diagnosis, symptoms, surgical treatment, tumor features, postoperative management, and follow-up were recorded. Nine STUMP cases were included. All patients reported menometrorrhagia and pelvic pain. In all women, the tumor lesion was single and intramural, and the mean diameter was 7.5 cm. Four women underwent laparotomic conservative surgery. The mean postoperative follow-up time was 36 months, and recurrences were observed in two patients. In conclusion, STUMP cases should be systematically discussed by tumor boards, pathologists with good expertise in gynecological diseases should examine the histological samples, and close surveillance is mandatory because of the possibility of recurrence or metastasis. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

BACKGROUND Uterine smooth muscle tumors (USMTs) constitute a group of histologic, genetic, and clinical heterogeneous tumors that include at least 6 major histologically defined tumor types: leiomyoma (ULM), mitotically active leiomyoma (MALM), cellular leiomyoma (CLM), atypical leiomyoma (ALM), uncertain malignant potential (STUMP), and leiomyosarcoma (LMS). Apart from ULM and LMS, the nature of these variants is not well defined. METHODS A total of 167 cases of different USMT variants were collected, reviewed, and diagnostically confirmed based on the World Health Organization and Stanford schemes. These included 38 cases of LMS, 18 cases of STUMP, 42 cases of ALM, 22 cases of CLM, 7 cases of MALM, and 40 cases of ULM. Molecular analysis included selected microRNAs (miRNAs), oncogenes, and tumor suppressors that are highly relevant to USMT. RESULTS Overall, 49% (17/35) of LMS cases and 7% (1/14) of STUMP cases died due to their USMT, but no deaths were attributed to ALM. miRNA profiling revealed that ALM and LMS shared similar miRNA signatures. P53 mutations and PTEN deletions were significantly higher in LMS, ALM, and STUMP compared with other USMT variants ( P < .01). In contrast, MED12 mutations were extremely common in ULM and MALM (>74%) but were significantly less common (<15%) in CLM, ALM, STUMP, and LMS ( P < .01). CONCLUSION Six types of USMT have different gene mutation fingerprints. ALM shares many molecular alterations with LMS. Our findings suggest that ALM may be a precursor lesion of LMS or have similar genetic changes during its early stage. Cancer 2014;120:3165-3177. © 2014 American Cancer Society. [ABSTRACT FROM AUTHOR]

Background: The diagnosis of uterine smooth muscle tumors depends on a combination of microscopic features. However, a small number of these tumors still pose difficult diagnostic challenges. Aim: To investigate progesterone receptor (PR) and p53 expression in leiomyomas (LMs), atypical leiomyomas (ALMs), smooth muscle tumors of uncertain malignant potential (STUMP), and leiomyosarcomas (Lass) and to evaluate the potential utility of the selected immunohistochemical markers in differentiating these tumors. Materials and methods: Immunohistochemical expression of PR and p53 was investigated in 41 uterine smooth muscle tumors comprising: 15 LMS, 4 STUMP, 6 ALM and 16 LM. Quantitative evaluation of PR and p53 expression was graded on a scale from 0 to 3+. Results: Leiomyosarcomas showed reduced PR expression. All LMs as well as ALMs and STUMP were stained intensely for PR. Conversely, LMS was strongly stained with p53, while the three non-sarcomatous groups (STUMP, ALM, LM) were either entirely negative or weakly stained for p53. Regarding both PR and p53 expression, the difference between the LMS group and the three non-sarcomatous groups was highly significant (p < 0.001). Combined high PR - low p53 expression was seen in all the 26 examined cases of the non-sarcomatous group including the STUMP cases and none of the LMS cases. Therefore, it represents a "benign" profile with 100% specificity in diagnosis of a non-sarcomatous tumor. Conclusion: Immunohistochemistry for PR and p53 is valuable as an adjunct tool to morphological assessment of problematic uterine smooth muscle tumors. [ABSTRACT FROM AUTHOR]