Safety and efficacy of sirolimus in recurrent intravenous leiomyomatosis, pulmonary benign metastatic leiomyomatosis, and leiomyomatosis peritonealis disseminata: a pilot study.

BACKGROUND: Intravenous leiomyomatosis (IVL), pulmonary benign metastatic leiomyomatosis (PBML), and leiomyomatosis peritonealis disseminata (LPD) are leiomyomas with special growth patterns and high postoperative recurrence rates. We report the safety and efficacy of a pilot study of sirolimus in the treatment of recurrent IVL, PBML, and recurrent LPD. METHODS: This was a pilot study to evaluate the safety and efficacy of sirolimus in the treatment of leiomyomatosis (ClinicalTrials.gov identifier NCT03500367) conducted in China. Patients received oral sirolimus 2 mg once a day for a maximum of 60 months or until disease progression, intolerable toxicity, withdrawal of consent, or investigator decision to stop. The primary end point of this study was the objective response rate. Secondary end points included safety and tolerability, disease control rate, and progression-free survival. RESULTS: A total of 15 patients with leiomyomatosis were included in the study, including five with recurrent IVL, eight with PBML and two with recurrent LPD. The median follow-up time was 15 months (range 6-54 months), nine patients (60%) had treatment-related adverse events (including all levels), and two patients had treatment-related grade 3 or 4 adverse events. The objective response rate was 20.0% (95% CI, 7.1-45.2%), and the disease control rate was 86.7% (95% CI, 62.1-96.3%). Partial response was achieved in three patients. The median response time in the three partial response patients was 33 months (range 29-36 months), and the sustained remission time of these three patients reached 0, 18, and 25 months, respectively. CONCLUSIONS: Sirolimus was safe and effective in the treatment of recurrent IVL, PBML, and recurrent LPD. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT03500367. Registered on 18 April 2018.

The clinicopathologic and molecular features, and treatment outcome of fumarate hydratase-deficient renal cell carcinoma: a retrospective comparison with type 2 papillary renal cell carcinoma.

BACKGROUND: To compare clinicopathologic, molecular features, and treatment outcome between fumarate hydratase-deficient renal cell carcinoma (FH-dRCC) and type 2 papillary renal cell carcinoma (T2 pRCC). METHODS: Data of T2 pRCC patients and FH-dRCC patients with additional next-generation sequencing information were retrospectively analyzed. The cancer-specific survival (CSS) and disease-free survival (DFS) were primary endpoint. RESULTS: A combination of FH and 2-succino-cysteine (2-SC) increased the rate of negative predictive value of FH-dRCC. Compared with T2 pRCC cases, FH-dRCC cases displayed a greater prevalence in young patients, a higher frequency of radical nephrectomy. Seven FH-dRCC and two T2 pRCC cases received systemic therapy. The VEGF treatment was prescribed most frequently, with an objective response rate (ORR) of 22.2% and a disease control rate (DCR) of 30%. A combined therapy with VEGF and checkpoint inhibitor reported an ORR of 40% and a DCR of 100%. FH-dRCC cases showed a shortened CSS (P = 0.042) and DFS (P < 0.001). The genomic sequencing revealed 9 novel mutations. CONCLUSIONS: Coupled with genetic detection, immunohistochemical biomarkers (FH and 2-SC) can distinguish the aggressive FH-dRCC from T2 pRCC. Future research is awaited to illuminate the association between the novel mutations and the clinical phenotypes of FH-dRCC in the disease progression.

Different clinical diagnosis end up in the same pathological diagnosis of intravascular leiomyomatosis: Two case reports.

RATIONALE: Intravascular/intravenous leiomyomatosis (IVL) is a peculiar variant of uterine leiomyoma that is classified as a histologically benign smooth muscle tumor with a biological behavior similar to that of a malignant tumor. It is characterized by the proliferation of leiomyomas spreading along the uterine and extrauterine venous circulation. PATIENT CONCERNS: Herein, we present 2 cases of IVL who had completely different clinical manifestations to stress the need for constant vigilance of IVL diagnosis and the understanding of uterine leiomyoma heterogenicity. Case 1 was registered for fever without specific triggering factors, irregular menstruation and clinically diagnosed uterine diverticula, while no information about fibroids was mentioned. Case 2 was characterized by an aggressively growing abdominal mass. With a large space-occupying lesion in the right abdominopelvic cavity and no imaging evidence of involvement of the iliac vein or above vein, the patient was initially diagnosed with multiple myomata. DIAGNOSES: Both patients' diagnoses were confirmed as IVL by histopathology. To our knowledge, the mass of case 1 is the minimum IVL in the English literature. INTERVENTIONS: Subtotal hysterectomy with bilateral salpingectomy was performed on the former, while total hysterectomy with bilateral salpingectomy was performed on the latter. OUTCOMES: Both patients were comfortable, and no relapse occurred. LESSONS: Two cases in the study showed 2 different proceeding stages of the same disease and corroborated multiple pathogeneses, which have been mentioned in the available literature on IVL. Our work provides both supplement for clinical data to facilitate further research and better understanding of special types of fibroids to clinicians.

Genetic and clinical characterization of a novel FH founder mutation in families with hereditary leiomyomatosis and renal cell cancer syndrome.

BACKGROUND: Hereditary leiomyomatosis and renal cell cancer syndrome is a rare autosomal dominant hereditary syndrome. Previously, we published the largest cohort of FH mutation carriers in Spain and observed a highly recurrent missense heterozygous variant, FH(NM_000143.4):c.1118A > G p.(Asn373Ser), in 104 individuals from 31 apparently unrelated families. Here, we aimed to establish its founder effect and characterize the associated clinical phenotype. RESULTS: Haplotype analysis confirmed that families shared a common haplotype (32/38 markers) spanning 0.61-0.82 Mb, indicating this recurrent variant was inherited from a founder ancestor. Cutaneous and uterine leiomyomatosis were diagnosed in 64.6% (64/99) and 98% (50/51) of patients, respectively, and renal cell cancer was present in 10.4% (10/96). The pathogenic FH_c.1118A > G variant is a Spanish founder mutation that originated 12-26 generations ago. We estimate that the variant may have appeared between 1370 and 1720. Individuals carrying this founder mutation had similar frequency of renal cell cancer and a higher frequency of renal cysts and leiomyomas than those in other cohorts of this syndrome. CONCLUSIONS: In the Spanish province of Alicante there is a high prevalence of HLRCC because of the founder mutation FH c.1118A > G; p.(Asn373Ser). The characterization of founder mutations provides accurate and specific information regarding their penetrance and expressivity. In individuals with suspected HLRCC from the province of Alicante, genetic testing by direct analysis of the founder FH c.1118A > G; p.(Asn373Ser) mutation may be a faster and more efficient diagnostic tool compared with complete gene sequencing.

MR imaging findings of stage I intravenous leiomyomatosis: a retrospective single-center study in 19 cases.

OBJECTIVES: The aim was to explore the magnetic resonance imaging (MRI) features of stage-I intravenous leiomyomatosis (IVL). MATERIALS AND METHODS: From January 2019 to January 2023, clinical, pathological, and MRI data were collected from 19 cases confirmed by surgical pathology. Two radiologists retrospectively measured the tumor sizes, T1WIs, T2WIs, and ADC values and evaluated contrast-enhanced T1WIs, DWIs, complications and parauterine infiltrations. The number of tumor cells and the total nuclear area were measured. The percentage of tumor cell area out of the total area was used as the tumor cell density. RESULTS: Nineteen patients with stage-I IVL aged 33 to 66 years (mean age: 46 ± 7.6 years) were included in this study. All 19 cases were located in the myometrium or parametrium, with a mean diameter of 11.2 ± 4.8 cm. Among these cases, 14 (73.6%) were associated with leiomyoma, and six (31.6%) involved the broad ligament. Isointensity was observed in the T1WIs of 12 cases (63.2%), while slight hypointensity was seen in five patients (26.3%). Isointensity was observed in the on T2WIs of four cases (21.1%), and iso- or slight hyperintensity was observed in 15 cases (78.9%). A significant difference was detected between the normalized T2WIs of IVL and myometrium (p < 0.001). A Pearson correlation test showed demonstrated a negative correlation between the ADC and tumor cell density values (r = - 0.946, p < 0.001). Tortuous vessels were present in 17 cases (89.5%) within or next to the lesions, and multiple winding cord-like filling defects were seen in 11 cases (57.9%) within the tortuous vessels on the T2WIs. CONCLUSION: Identifying the characteristic MRI features of stage-I IVL helped improve the diagnostic accuracy achieves for this rare tumor. Stage-I IVL often presents as a large mass accompanied by leiomyoma, and it easily invades the broad ligament. TIWI signals exhibited isointensity, and T2WI signals contained iso- or slight hyperintensity. Tortuous vessels were present within or next to the lesions, and multiple winding cord-like filling defects were observed within the tortuous vessels on the T2WIs.

The use of Clinicopathological, immunohistochemistry and molecular detection in the diagnosis of fumarate hydratase-deficient uterine leiomyomas.

BACKGROUND: Fumarate hydratase-deficient uterine leiomyomas (FH-dUL) are rare, accounting for only 0.4-1.6% of uterine leiomyomas. FH germline mutation gene is associated with hereditary leiomyomatosis and renal cell carcinoma syndrome (HLRCC). METHODS: In this study, we aim to investigate Clinicopathological features and FH mutation in FH-dUL. We performed a retrospective analysis of 300 cases of uterine leiomyoma, diagnosed from January 2017 to December 2021, within the archives of the Department of Pathology at Peking University People's Hospital. In our review of the immunohistochemical(IHC) staining was performed on 300 uSMTs to detect FH deficiency. RESULTS: We identified 21cases (21/300,7%) of FH-dUL. Nineteen cases (6.33%) displayed negative FH. Twenty-one cases (7%) displayed 2SC diffuse plasma and nuclear staining. The most common FH-d morphological features included staghorn vasculature ( 100%,21/21), alveolar-pattern oedema (71.43%, 15/21), scattered bizarre nuclei (23.81%, 5/21), eosinophilic cytoplasmic (rhabdoid) inclusions (47.62%, 10/21), significant eosinophilic nucleolus with peri-nucleolus hollowing (23.81%, 5/21), ovoid nuclei sometimes arranged in chains (9.52%, 2/21). DNA sequencing for the 21 cases was performed using Next Generation Sequencing (NGS). 6 cases were detected significant variations for the FH gene, 11 cases were detected FH gene mutation forvariants of uncertain significance (VUS), and 2 cases were detected a TP53 gene mutation. No related mutations were detected in the other two cases. CONCLUSIONS: FH-dUL is rare. The combination of predictive Clinicopathological evaluation,FH and 2SC IHC test, and molecular test were helpful for the screening of FH-dUL from uSMTs,or even the screening of HLRCC.

Unraveling the challenges of intravenous leiomyomatosis: a retrospective analysis of 11 cases.

OBJECTIVE: This study provides a concise overview of diagnostic and treatment strategies for intravenous leiomyomatosis (IVL), a rare disease with nonspecific clinical manifestations, based on cases from a tertiary referral hospital in China. METHODS: We retrospectively analyzed 11 premenopausal patients with confirmed IVL between 2018 and 2022. Clinical data from Ultrasound, Enhanced CT, and MRI were studied, along with surgical details, postoperative pathology, and follow-up information. RESULTS: Premenopausal patients showed no disease-specific symptoms, with 90.9% having a history of gynecological or obstetric surgery, and 72.7% having prior uterine fibroids. Cardiac involvement was evident in two cases, with echocardiography detecting abnormal floating masses from the inferior vena cava. Pelvic ultrasound indicated leiomyoma in 90.9% of cases, with ≥ 50 mm size. Surgery was the primary treatment, and lesions above the internal iliac vein resulted in significantly higher intraoperative blood loss (median 1300 ml vs. 50 ml, p = 0.005) and longer hospital stays (median 10 days vs. 4 days, p = 0.026). Three patients with lesions above the inferior vena cava required combined surgery with cardiac specialists. Recurrence occurred in 2 out of 11 patients with incomplete lesion resection. CONCLUSIONS: IVL mainly affects premenopausal women with uterine masses, primarily in the pelvic cavity (Stage I). Pelvic ultrasound aids early screening, while Enhanced CT or MR assists in diagnosing and assessing venous lesions. Complete resection is crucial to prevent recurrence. Lesions invading the internal iliac vein and above pose higher risks during surgery. A multidisciplinary team approach is essential for patients with lesions above the inferior vena cava, with simultaneous surgery as a potential treatment option.

[Diagnosis and treatment of intravenous leiomyomatosis].

Intravenous leiomyomatosis is a rare type of tumor that is histologically benign but biologically invasive. It originates from the smooth muscle of the uterine or the uterine vein. It can grow through the uterus and extend into the pelvic cavity, or grow along the veins without invading the wall of the venous vessel itself. The tumors are estrogen-dependent and can metastasize through the bloodstream. Thus, in addition to continuous growth, some tumors exhibit isolated growths in the venous system and heart chambers or show disseminated growth in the lungs, although distant metastasis to other regions usually do not occur. Currently, there is limited research on this disease, the majority of which are case reports, surgical experience summaries, and differentiation from ordinary gynecological myomas in terms of pathogenesis and radiological diagnostic experience. There are two main theories on the origin of the disease: uterine smooth muscle and smooth muscle of the uterine veins. Some studies have verified the role of estrogen, progesterone receptor-related pathways, and angiogenesis in the development of the disease. The clinical symptoms of this disease are varied, depending on the affected area. In the early stages, when the tumor only affects the pelvic cavity, patients show mild symptoms resulting from pelvic organ compression. When it progresses to the inferior vena cava and heart, patients show more complex symptoms resulting from venous return obstruction, cardiac obstruction, and hemodynamics appearing. Different institutions have proposed different disease staging and classification strategies for different clinical purposes. Some are based on the affected area of the lesion; others are based on the size of the tumor. Although surgery remains the main treatment for this disease, the specific surgical approach, adjuvant drug therapy, and prognosis still need further exploration.

The Role of Morphology in Predicting Fumarate Hydratase-deficient Uterine Leiomyomas in Young Women.

Hereditary leiomyomatosis and renal cell carcinoma is caused by germline mutations in the fumarate hydratase (FH) gene and is associated with an increased incidence of leiomyomas and a potentially aggressive variant of renal cell carcinoma. Pathologic evaluation of uterine leiomyoma can provide an opportunity for early recognition of the syndrome. We reviewed all archived slides of the cases to identify the characteristic morphologic features described for FH-deficient leiomyomas. We performed immunohistochemistry on whole sections of patients with uterine leiomyoma to evaluate for both FH and 2-succinocysteine (2SC) expression. Of the 106 cases, 19 showed the characteristic eosinophilic nucleoli with perinuclear halos, and 24 revealed a characteristic eosinophilic cytoplasmic inclusion consisting of pink globules present within the cytoplasm. Both of these morphologic findings were present together in 15 cases, and hemangiopericytomatous vessels were detected in 23 cases. The loss of FH protein expression was detected in 14 out of 106 cases (13%), and 13 out of 106 cases (12%) were positive for 2SC. We detected 10 cases with both 2SC-positive and FH expression loss. The presence of eosinophilic nucleoli with perinuclear halos and eosinophilic cytoplasmic inclusion was associated with both loss of FH protein expression and 2SC positivity ( P < 0.001). These findings underscore the importance of hematoxylin and eosin-based predictive morphology in FH-deficient uterine leiomyomas. Therefore, morphologic assessment of uterine leiomyomas for features of FH deficiency can serve as a screening tool for hereditary leiomyomatosis and renal cell carcinoma syndrome, allowing patients to be divided according to their hereditary risk assessment.

Cryptic splice mutation in the fumarate hydratase gene in patients with clinical manifestations of Hereditary Leiomyomatosis and Renal Cell Cancer.

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is an autosomal dominant condition characterized by the development of cutaneous and uterine leiomyomas and risk for development of an aggressive form of papillary renal cell cancer. HLRCC is caused by germline inactivating pathogenic variants in the fumarate hydratase (FH) gene, which encodes the enzyme that catalyzes the interconversion of fumarate and L-malate. We utilized enzyme and protein mobility assays to evaluate the FH enzyme in a cohort of patients who showed clinical manifestations of HLRCC but were negative for known pathogenic FH gene variants. FH enzyme activity and protein levels were decreased by 50% or greater in three family members, despite normal FH mRNA expression levels as measured by quantitative PCR. Direct Nanopore RNA sequencing demonstrated 57 base pairs of retained intron sequence between exons 9 and 10 of polyadenylated FH mRNA in these patients, resulting in a truncated FH protein. Genomic sequencing revealed a heterozygous intronic alteration of the FH gene (chr1: 241498239 T/C) resulting in formation of a splice acceptor site near a polypyrimidine tract, and a uterine fibroid obtained from a patient showed loss of heterozygosity at this site. The same intronic FH variant was identified in an unrelated patient who also showed a clinical phenotype of HLRCC. These data demonstrate that careful clinical assessment as well as biochemical characterization of FH enzyme activity, protein expression, direct RNA sequencing, and genomic DNA sequencing of patient-derived cells can identify pathogenic variants outside of the protein coding regions of the FH gene.

Extrauterine leiomyomatosis, the great mimicker.

OBJECTIVES: Describe the radiographic features of the different forms of extrauterine leiomyomatosis. CONCLUSIONS: Leiomyomas with a rare growth pattern occur most often in women of reproductive age and with a history of hysterectomy. Extrauterine leiomyomas present a greater diagnostic challenge because they may mimic malignancies, and serious diagnostic errors may result.

In deep bioinformatic characterization of a novel fumarate hydratase variant FH c.199T > G; (p.Tyr67Asp) in hereditary leiomyomatosis and renal cell carcinoma.

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is a rare, autosomal dominant tumor predisposition syndrome characterized by variable development of multiple skin and uterus leiomyomas and aggressive forms of renal cell carcinoma (RCC). Mutations in fumarate hydratase (FH), one of the proteins in homologous recombination repair, precede the development of HLRCC with high penetrance. Considering the risk of early metastasis of RCC, FH has been included in mutation screening panels. The identification of a pathogenic FH variant guides the screening for tumors in the carriers. However, variants of uncertain significance (VUS) are frequent findings, limiting the clinical value of the mutation screening. Here, we describe the associated phenotype and an in-depth, multi-step Bioinformatic evaluation of the germline FH c.199T > G (p.Tyr67 > Asp) variant segregated in an HLRCC family. Evidence for FH c.199T > G; (p.Tyr67Asp) pathogenicity includes the variant segregation with the disease in three affected family members, its absence in populational databases, and the deep evolutionary conservation of the Tyr67 residue. At the protein level, this residue substitution causes the loss of molecular bonds and ionic interactions, affecting molecular dynamics and protein stability. Considering ACMG/AMP criteria, we propose the reclassification of the FH c.199T > G; (p.Tyr67Asp) variant to "likely pathogenic". In addition, the in-depth, in silico approach used here allowed us to understand how and why FH c.199T > G; (p.Tyr67Asp) could cause HLRCC. This could help in clinical management decisions concerning the monitoring of unaffected family members having this variant.

Intravenous leiomyomatosis of the uterus: Preoperative and intraoperative assessment.

OBJECTIVE: To assess factors influencing preoperative diagnosis and hemorrhage during surgery with uterine intravenous leiomyomatosis. METHODS: This retrospective single-institution study used univariate analysis and multivariate models to investigate potential factors contributing to preoperative diagnosis and hemorrhage during surgery associated with intravenous leiomyomatosis in 135 patients from January 2012 to April 2022. Risk factors for disease recurrence were also investigated. The SPSS statistical analysis package was used for data analysis. RESULTS: Previous myomectomy or fibroid ablation and tumor location on color Doppler were related to preoperative diagnosis (P = 0.031 and P = 0.003, respectively). Multivariate regression analysis demonstrated that lesions extending to the broad ligament were the only factors affecting preoperative diagnosis (odds ratio [OR] 5.383, 95% confidence interval [CI] 1.49-19.47). Univariate analysis showed that previous myomectomy or fibroid ablation (P = 0.017), tumor location (P = 0.027), and parauterine involvement (P = 0.014) were associated with intraoperative hemorrhage. Parauterine involvement was an independent risk factor for increased bleeding (OR 1.36, 95% CI 1.14-3.92). Six patients (4.4%) relapsed. The present study demonstrated that age (P = 0.031) and surgical type (P < 0.001) might be associated with disease recurrence. CONCLUSIONS: Treatment emphasis should focus on lesions extending to the broad ligament. Intraoperative bleeding associated with parauterine involvement should be stopped as effectively as possible.

Laterally extended endopelvic resection as part of the surgical management of disseminated retroperitoneal leiomyomatosis mimicking low-grade sarcoma in a patient with a solitary kidney.

Leiomyomas are common benign uterine smooth muscle tumours. Rarer subsets may demonstrate aggressive extrauterine growth which mimic metastatic disease. We discuss the case of a female patient in her 40s, with a long-standing atrophic right kidney, presenting with a 17 cm uterine mass demonstrating bilateral para-aortic and pelvic sidewall spread. Although biopsies favoured the diagnosis of a benign tumour, a leiomyosarcoma could not be excluded. The surgical complexity of the case was compounded by a tumour residing close to the only functioning kidney and engulfment of the inferior mesenteric artery. The surgical procedures indicated were a radical hysterectomy, the laterally extended endopelvic resection procedure to achieve clear margins in the pelvic sidewall and a left hemicolectomy. In the absence of formal guidelines, we present this challenging case to provide clarity into the histological assessment and surgical management of rare leiomyomas, as well as an overview of the current literature.

[Fumarate hydratase deficient uterine leiomyoma: a clinicopathological and molecular analysis of 80 cases].

Objective: To investigate the clinicopathologic and molecular characteristics of fumarate hydratase (FH) deficient uterine leiomyoma. Methods: Eighty cases of FH deficient uterine leiomyoma were diagnosed from April 2018 to September 2022 in Department of Pathology, Peking University Third Hospital. Sanger sequencing of FH gene exons (exon 1-10) were performed on tumor tissues and matched non-tumor tissues/peripheral blood for all cases. FH immunohistochemistry were performed in 74 cases; S-(2-succino)-cysteine (2SC) were also detected by immunohistochemistry in five cases. Results: Patients' age ranged from 18 to 54 (36.0±7.5) years, with more than 60% exhibiting clinical symptoms of multiple and large leiomyomas (the median diameter was 70 mm). More than four histologic features, including staghorn vasculature, alveolar-pattern edema, bizarre nuclei, oval nuclei arranged in chains, prominent eosinophilic nucleoli with perinucleolar haloes and eosinophilic intracytoplasmic globules were observed in 98.5% (67/68) patients. The immunohistochemical sensitivity of FH and 2SC were 97.3% and 100%, respectively. Based on the Sanger sequencing results, the cases were divided into germline variant group (31 cases), somatic variant group (29 cases) and no variant group (20 cases). Sixty-nine percent (20/29) of the patients with FH germline variation had clear family history. Conclusions: Clinical features, histological morphology, FH and 2SC immunohistochemistry and Sanger sequencing have their own significance and limitations in differential diagnosis of FH deficient uterine leiomyoma. In clinical practice, the above information should be fully integrated and studied for accurate pathologic diagnosis and selection of patients with FH germline variation.

Two oncomiRs, miR-182-5p and miR-103a-3p, Involved in Intravenous Leiomyomatosis.

Leiomyomas, also referred to as fibroids, belong to the most common type of benign tumors developing in the myometrium of the uterus. Intravenous leiomyomatosis (IVL) tends to be regarded as a rare type of uterine leiomyoma. IVL tumors are characterized by muscle cell masses developing within the uterine and extrauterine venous system. The underlying mechanism responsible for the proliferation of these lesions is still unknown. The aim of the study was to investigate the expression of the two epigenetic factors, oncomiRs miR-182-5p and miR-103a-3p, in intravenous leiomyomatosis. This study was divided into two stages: initially, miR-182-5p and miR-103a-3p expression was assessed in samples coming from intravenous leiomyomatosis localized in myometrium (group I, n = 6), intravenous leiomyomatosis beyond the uterus (group II; n = 5), and the control group, i.e., intramural leiomyomas (group III; n = 9). The expression level of miR-182-5p was significantly higher in samples coming from intravenous leiomyomatosis (group I and group II) as compared to the control group (p = 0.029 and p = 0.024, respectively). In the second part of the study, the expression levels of the studied oncomiRs were compared between seven samples delivered from one woman during a four-year observation. The long-term follow-up of one patient demonstrated significantly elevated levels of both studied oncomiRs in intravenous leiomyomatosis in comparison to intramural leiomyoma samples.

A Missense Mutation c.1132G > A in Fumarate Hydratase (FH) Leads to Hereditary Leiomyomatosis and Renal Cell Cancer (HLRCC) Syndrome and Insights into Clinical Management in Uterine Leiomyomata.

BACKGROUND: HLRCC syndrome is a hereditary cancer predisposition syndrome caused by heterozygous germline pathogenic variant of the fumarate hydratase (FH) gene and characterized by cutaneous leiomyomas (CL), uterine leiomyomas (UL), and renal cell carcinoma (RCC). Loss of function variant of FH gene inactivates the Kreb's cycle enzyme activity and predisposes individuals with such variant to the development of HLRCC. METHODS: Next-generation sequencing (NGS) and Sanger confirmation were given to family members accessible. Following that, a functional study in vitro was performed to further confirm the pathogenicity of the variant. FH-Wild type (FH-WT) and FH-mutant (FH-MUT) (E378K) plasmid were constructed and transfected into 293T and uterine leiomyoma cell lines, respectively. Proliferation assessment was executed to show how this mutation affects the growth of uterine leiomyoma. qPCR and Western blotting were performed to investigate the change of transcription and translation of FH with mutation (E378K), and FH enzyme assay activity were tested in 293T cells with mutation and wild-type plasmids. RESULTS: Here, we presented two families with the same missense variant (c.1132G > A) that has not been reported as a germline mutation in hereditary uterine leiomyomas before and classified as VUS in gene databases. Our in vitro experiments supported the pathogenicity of this missense variant, especially in uterine leiomyomata. CONCLUSIONS: According to the American College of Medical Genetics (ACMG) guideline, the E378K variant was classified as likely pathogenic (with evidence PS4_support, PS3_support, PM2_support, PP1, PP3 and PP4 evidence). Further insights into clinical management in uterine leiomyomata were discussed and should be practiced in gynecological clinical settings.