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

Abstract

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.

Case report: Spontaneous rupture of leiomyosarcoma uteri 8 months after primary laparoscopic surgery of STUMP

“…Ultrasound examination is the first step in the evaluation of uterine tumors; however, a limited field of view is a problem with large tumors. Some sonographic features, such as gross tumor size (>5 cm), highly vascularized mass, irregular outline, and necrotic areas, are more often linked to LMS and STUMP ( 11 ). Morphological uterine sonographic assessment (MUSA) has been proposed by consensus to describe the ultrasonographic features of the myometrium and uterine mass.…”

“…Morphological uterine sonographic assessment (MUSA) has been proposed by consensus to describe the ultrasonographic features of the myometrium and uterine mass. According to the MUSA, STUMP shows higher color Doppler enhancement than that in benign masses due to higher intralesional and perilesional vascularization ( 11 ).…”

“…There is no consensus on the use of adjuvant chemotherapy ( 10 ). The clinical symptoms and morphological characteristics of malignant and benign uterine tumors widely overlap, making preoperative diagnosis difficult ( 11 ). There is also a significant overlap in terminologies, such as STUMP, atypical leiomyoma, atypical leiomyoma with a low risk of recurrence, and atypical leiomyoma with low malignant potential, which contributes to confusion and unequivocal diagnosis ( 11 ).…”

“…The clinical symptoms and morphological characteristics of malignant and benign uterine tumors widely overlap, making preoperative diagnosis difficult ( 11 ). There is also a significant overlap in terminologies, such as STUMP, atypical leiomyoma, atypical leiomyoma with a low risk of recurrence, and atypical leiomyoma with low malignant potential, which contributes to confusion and unequivocal diagnosis ( 11 ). Usually, patients with symptom onset require surgical intervention that depends on the patient’s age, fertility requirements, tumor type, and surgical skill.…”

“…After patients undergo laparoscopy or laparotomy (myomectomy or hysterectomy) and a definitive histopathological STUMP diagnosis is made, further medical treatment depends on the requirements for fertility preservation ( 4 ). Myomectomy is an acceptable choice for patients who want to preserve fertility, but surgical radicalization should be proposed when childbearing is completed ( 3 , 11 ). The reported recurrence rate after primary surgical resection varies from 7 to 36.4%, and recurrence can present as STUMP or LMS ( 14 ).…”