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BACKGROUND: Mesenchymal neoplasms of the uterus encompass a diverse group of tumors, with varying characteristics and origins, collectively accounting for 8% of uterine malignancies. The most common variants include uterine leiomyosarcoma, low-grade and high-grade endometrial stromal sarcoma, adenosarcoma, and undifferentiated sarcoma. Clinical presentation is often nonspecific and can lead to delayed diagnosis. Uterine sarcomas are generally aggressive, resulting in poorer prognosis compared to carcinomas. Recent advances in molecular techniques, such as next-generation sequencing (NGS), have led to the identification of new subtypes of uterine sarcomas, including COL1A1::PDGFB fusion-associated fibrosarcoma, which has a specific chromosomal translocation t(17;22)(q22;q13). Imatinib, a tyrosine kinase inhibitor (TKI), is an effective treatment for dermatofibrosarcoma protuberans (DFSP), marked by this translocation. CASE: We present the case of a 42-year-old woman diagnosed with COL1A1::PDGFB fusion-associated uterine fibrosarcoma. The patient underwent total hysterectomy and excision of the tumor, initially misdiagnosed as a low-grade leiomyosarcoma. Subsequent histological examination, immunohistochemistry, and fluorescence in situ hybridization (FISH) confirmed the diagnosis. After 10 months, disease recurrence was detected, and Imatinib therapy was initiated at a dose of 400 mg daily. An allergic reaction led to a temporary discontinuation, but upon resumption with appropriate medication, a positive radiological response was observed. The patient achieved a complete remission after 2 years and is still on Imatinib treatment. CONCLUSIONS: COL1A1::PDGFB fusion-associated uterine fibrosarcoma is an extremely rare mesenchymal neoplasm. In a case we present herein, we treated a patient with imatinib as first-line medical therapy. The patient is currently in complete remission after 37 months from treatment start. To the best of our knowledge, this represents a unique observation. We also provide a detailed literature review of the published cases so far. Prospective case series are needed to further understand the natural history of these tumors and optimize treatment strategies.

Background: Leiomyosarcoma (LMS) of vascular origin is a rare entity of soft tissue sarcomas. Although they arise mostly from retroperitoneal major vascular structures, some encountered cases may arise from the smaller vascular structures of the thigh as the femoral vein. Due to their origin from the vascular structures, they represent a diagnostic challenge as they may be misdiagnosed as deep vein thrombosis (DVT). Case presentation: We present a case of a 45-year-old woman with left femoral and iliac vein LMS that was previously described in the vascular ultrasound (US) report as extensive DVT involving the femoral and external iliac veins. The patient did not improve after receiving the prescribed anticoagulants. Seven months later, the patient underwent computerized tomography (CT) with contrast, revealing a soft tissue mass in the anatomical site of the left common femoral and external iliac veins. The patient underwent both US-guided tru-cut biopsy and incisional biopsy from the iliac lymph nodes which revealed leiomyosarcoma. Materials and methods: The patient underwent both vascular ultrasound and magnetic resonance imaging of the pelvis and the left thigh at the time of the first presentation. Seven months later, she underwent contrast-enhanced CT of the abdomen and pelvis. Outcome: The patient was referred to the oncology department to receive the appropriate chemotherapy protocol as the tumor was inoperable. Conclusions: Although leiomyosarcoma of vascular origin is a rare entity of neoplasms, it is usually underestimated. A high index of suspicion would help the clinician to suspect such a neoplasm and save time for early diagnosis and management. Special caution should be taken for patients with venous thrombosis not improving on anticoagulants. When there is suspicion, other modalities such as computerized tomography and magnetic resonance imaging help confirm the diagnosis. [ABSTRACT FROM AUTHOR]

Background: Perivascular epithelioid cell tumor (PEComa) is usually a benign perivascular tumor that expresses both melanocytic and myogenic cell markers. We report 2 cases of advanced malignant uterine perivascular epithelioid cell tumor (PEComa) in a 74-year-old woman and a 50-year-old woman undergoing surgery in our center. Case Reports: Case 1: A 74-year-old woman presented with a painful and massive abdominal mass. The imaging revealed a 19-cm necrotic mass close to the mesentery, a suspicious lesion in the uterus, and a probable liver metastasis. The pathological diagnosis was quite difficult with mixed features of leiomyosarcoma and PEComa with an uncommon immunohistochemistry staining pattern. Therefore, we gave a diagnosis of sarcoma with PEComalike features. Case 2: A 50-year-old woman with metrorrhagia and abdominal pain. Imaging revealed a 7-cm mass in the uterus and suspicious metastatic lesions in the lung and the liver. The immunohistochemistry pattern was typical, with a strong positivity of Human Melanoma Black-45 (HMB-45) and focal positivity of H-Caldesmon. The patient benefited from targeted adjuvant therapy (MTOR inhibitor-based), with 8-month a follow-up showing no recurrence for this Grade IV PEComa mutated for TP53, ATRX, and TSC1. Conclusions: We have report 2 cases of metastatic PEComa with different clinicopathological features. An overlap remains between characteristics of PEComas and smooth-muscle tumors. At present, there are no known pathognomonic findings or specific diagnostic markers. [ABSTRACT FROM AUTHOR]

Introduction: Leiomyosarcoma (LMS) is a malignancy with smooth muscle differentiation. Metastatic LMS is associated with poor prognosis and limited efficacy of systemic treatment. Novel treatment modalities are desperately needed for this entity. Case Presentation: We report the first use of pembrolizumab plus pharmacologic ascorbate in 3 patients with metastatic LMS. All cases resulted in persistent objective responses and disease control significantly better than has been reported with chemotherapy or other immunotherapeutic approaches. Three patients with metastatic LMS, one each of uterine, vascular, and soft tissue origin, were treated with pembrolizumab plus pharmacologic ascorbate. The patient with uterine LMS received combination therapy at presentation and had persistent response for 12 months, which is ongoing. The patient with metastatic LMS of the inferior vena cava received combination therapy at presentation and had persistent response for 12 months, at which time new metastases were found. The patient with soft tissue LMS had disease progression on pembrolizumab monotherapy prior to the addition of ascorbate, after which she had a 17-month response, which is ongoing. No side effects attributed to treatment were reported. Conclusion: Pembrolizumab plus pharmacologic ascorbate is a novel immunotherapeutic approach and warrants further study in LMS. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate outcomes following percutaneous image‐guided ablation of soft tissue sarcoma metastases to the liver. Materials and Methods: A single‐institution retrospective analysis of patients with a diagnosis of metastatic soft tissue sarcoma who underwent percutaneous image‐guided ablation of hepatic metastases between January 2011 and December 2021 was performed. Patients with less than 60 days of follow‐up after ablation were excluded. The primary outcome was local tumor progression‐free survival (LPFS). Secondary outcomes included overall survival, liver‐specific progression‐free survival. and chemotherapy‐free survival. Results: Fifty‐five patients who underwent percutaneous ablation for 84 metastatic liver lesions were included. The most common histopathological subtypes were leiomyosarcoma (23/55), followed by gastrointestinal stromal tumor (22/55). The median treated liver lesions was 2 (range, 1–8), whereas the median size of metastases were 1.8 cm (0.3–8.7 cm). Complete response at 2 months was achieved in 90.5% of the treated lesions. LPFS was 83% at 1 year and 80% at 2 years. Liver‐specific progression‐free survival was 66% at 1 year and 40% at 2 years. The overall survival at 1 and 2 years was 98% and 94%. The chemotherapy‐free holiday from the start of ablation was 71.2% at 12 months. The complication rate was 3.6% (2/55); one of the complications was Common Terminology Criteria for Adverse Events grade 3 or higher. LPFS subgroup analysis for leiomyosarcoma versus gastrointestinal stromal tumor suggests histology‐agnostic outcomes (2 years, 89% vs 82%, p =.35). Conclusion: Percutaneous image‐guided liver ablation of soft tissue sarcoma metastases is safe and efficacious. Image‐guided ablation of sarcoma metastasis is a promising modality for treating sarcoma metastases to the liver, with a local tumor progression‐free survival of 83% and 80% at 1 and 2 years. Subgroup analysis demonstrated no significant differences between the local tumor progression‐free survival of gastrointestinal stromal tumor versus leiomyosarcoma, suggesting a histology‐agnostic treatment paradigm. [ABSTRACT FROM AUTHOR]

Up to half of patients with leiomyosarcoma (LMS) present with distant metastases, most commonly in the lungs. Despite guidelines around managing metachronous oligometastatic disease, limited evidence exists for synchronous isolated lung metastases (SILMs). Our histology-specific study describes management patterns and outcomes for patients with LMS and SILM across disease sites. We used the National Cancer Database to analyze patients with LMS of the retroperitoneum, extremity, trunk/chest/abdominal wall, and pelvis with SILM. Patients with extra-pulmonary metastases were excluded. We identified factors associated with primary tumor resection and receipt of metastasectomy. Outcomes included median, 1-year, and 5-year overall survival (OS) across treatment approaches using log-rank tests, Kaplan–Meier curves, and Cox proportional hazard models. We identified 629 LMS patients with SILM from 2004 to 2017. Patients were more likely to have resection of their primary tumor or lung metastases if treated at an academic center compared to a community cancer center. Five year OS for patients undergoing both primary tumor resection and metastasectomy was 20.9% versus 9.2% for primary tumor resection alone, and 2.6% for nonsurgical patients. Median OS for all-comers was 15.5 mo. Community treatment site, comorbidity score, and larger primary tumors were associated with worse survival. Chemotherapy, primary resection, and curative intent surgery predicted improved survival on multivariate Cox regression. An aggressive surgical approach to primary LMS with SILM was undertaken for select patients in our population and found to be associated with improved OS. This approach should be considered for suitable patients at high-volume centers. [ABSTRACT FROM AUTHOR]

Key Clinical Message: LMS of IVC needs a multidisciplinary approach. Surgical excision with free margin is the cornerstone of management. Upon case‐by‐case selection, adjuvant chemotherapy may play a role in better oncologic outcome. Leiomyosarcoma (LMS) of the inferior vena cava (IVC) is a rare form of mesenchymal origin malignancy with less than 400 cases reported to date. Surgery is the mainstay of management but it requires vast experience in vascular and visceral surgery to attain a free tumor margin. Subsequent adjuvant treatment with chemotherapy and radiation remains as an area of gray zone. We report the case of a 61‐year‐old man with an 8‐month history of abdominal pain. Upon physical examination, an ill‐defined mass over the right side of the lower abdomen and bilateral lower extremity edema were detected. Abdominal ultrasound with Doppler revealed a right‐side retroperitoneal mass invading the IVC with extensive venous thrombosis for which anticoagulation was initiated. Computed Tomography of the abdomen revealed a huge heterogeneously enhancing mass involving the whole length of the infrarenal IVC obstructing the IVC lumen with collateral veins draining through the paralumbar veins and inferior epigastric veins bilaterally. With a top differential of primary IVC LMS, a midline longitudinal laparotomy was performed with an intraoperative finding of a tumor arising from the infra‐renal IVC which was excised. Gore‐Tex graft was used to reconstruct the IVC. There was an injury to the right common iliac artery and it was repaired by end‐to‐end anastomosis. Histopathology confirmed a high‐grade LMS of the IVC and surgical margin status was unknown. He was given adjuvant Chemotherapy consisting of Doxorubicin and Dacarbazine. He has been on follow‐up at the Oncology side with a good performance status. [ABSTRACT FROM AUTHOR]

Myristoylation, the N-terminal addition of the fatty acid myristate to proteins, regulates membrane-bound signal transduction pathways important in cancer cell biology. This modification is catalyzed by two N-myristoyltransferases, NMT1 and NMT2. Zelenirstat is a first-in-class potent oral small molecule inhibitor of both NMT1 and NMT2 proteins. Patients with advanced solid tumors and relapsed/refractory (R/R) B-cell lymphomas were enrolled in an open label, phase I dose escalation trial of oral daily zelenirstat, administered in 28-day cycles until progression or unacceptable toxicity. The endpoints were to evaluate dose-limiting toxicities (DLT) to establish a maximum tolerated dose (MTD), pharmacokinetic parameters, and anticancer activity. Twenty-nine patients were enrolled (25 advanced solid tumor; 4 R/R B-cell lymphoma) and 24 were DLT-evaluable. Dosing ranged from 20 mg once daily (OD) to 210 mg OD without DLT, but gastrointestinal DLTS were seen in the 280 mg cohort. MTD and recommended phase 2 dose were 210 mg OD. Common adverse events were predominantly Gr ≤ 2 nausea, vomiting, diarrhea, and fatigue. Plasma concentrations peaked at 2 h with terminal half-lives averaging 10 h. Steady state was achieved by day 15, and higher doses achieved trough concentrations predicted to be therapeutic. Stable disease as best response was seen in eight (28%) patients. Progression-free survival and overall survival were significantly better in patients receiving 210 mg OD compared to those receiving lower doses. Zelenirstat is well-tolerated, achieves plasma exposures expected for efficacy, and shows early signs of anticancer activity. Further clinical development of zelenirstat is warranted. [ABSTRACT FROM AUTHOR]

Background: Leiomyosarcoma is a tumor that can develop in any organ that contains smooth muscles. Although leiomyosarcoma is common, its epididymal localization is quite rare. Case presentation: A 79-year-old male Chinese Han patient presented with mild pain in the right groin and scrotum for 3 years concomitant with right scrotal swelling. Ultrasonography and magnetic resonance imaging of the scrotum showed a irregular and heterogeneous mass that was extratesticular. Right high orchiectomy was performed, and pathological examination of the resected specimen confirmed the diagnosis of leiomyosarcoma of the epididymis with surgical margins clear of tumor. Conclusion: Epididymal leiomyosarcoma is rare and difficult to diagnose preoperatively. The final diagnosis of epididymal leiomyosarcoma requires histologic examination. Resection must be extensive and complete. The effect of chemotherapy and radiation on the epididymal leiomyosarcoma remains unclear. Recurrence is common, so follow-up is necessary. [ABSTRACT FROM AUTHOR]

The primary hepatic leiomyosarcoma is a rare malignant tumor arising from the smooth muscle cells in the hepatic vessels, bile ducts, and ligamentum teres. It is considered a subtype of hepatic sarcomas. We report awkward 18F-FDG PET-CT findings of a primary hepatic leiomyosarcoma masquerading as a benign hepatic tumor, which were confirmed by histopathological and immunohistochemical examinations in a 78-year-old woman. [ABSTRACT FROM AUTHOR]

Simple Summary: While sun exposure and associated tissue changes stemming from ultraviolet radiation are closely associated with the most common forms of skin cancer, far less is known regarding rare types of skin cancer. In this study, for the first time, we used a light microscopy technique to evaluate connective tissue changes in samples from patients with six different types of rare skin cancers, assessing the relationship between these changes, patient age, and whether tumors arose on sun-exposed parts of the body. We found that these tissue changes were most pronounced for patients with specific cancers known to be linked to chronic sun damage and tumors arising on sun-exposed parts of the body. We also noted tumor type-specific trends in terms of sex ratios, sites of tumor presentation, and the relationship between the development of particular tumors and patient immunosuppression. Our results are important and novel as they expand the available data associated with these rare skin cancers while also offering insight into the value of differentiating among these tumor types based on their relationship with sun exposure, potentially informing preventative, diagnostic, and/or therapeutic approaches. (1) Background: Rare skin cancers include epithelial, neuroendocrine, and hematopoietic neoplasias as well as cutaneous sarcomas. Ultraviolet (UV) radiation and sunburns are important drivers for the incidence of certain cutaneous sarcomas; however, the pathogenetic role of UV light is less clear in rare skin cancers compared to keratinocyte cancer and melanoma. In this study, we compared the degree of actinic elastosis (AE) as a surrogate for lifetime UV exposure among selected rare skin cancers (atypical fibroxanthoma [AFX], pleomorphic dermal sarcoma [PDS], dermatofibrosarcoma protuberans [DFSP], Kaposi sarcoma [KS], Merkel cell carcinoma [MCC], and leiomyosarcoma [LMS]) while taking into account relevant clinical variables (age, sex, and body site). (2) Methods: We newly established a semi-quantitative score for the degree of AE ranging from 0 = none to 3 = total loss of elastic fibers (basophilic degeneration) and multiplied it by the perilesional vertical extent (depth), measured histometrically (tumor-associated elastosis grade (TEG)). We matched the TEG of n = 210 rare skin cancers from 210 patients with their clinical variables. (3) Results: TEG values were correlated with age and whether tumors arose on UV-exposed body sites. TEG values were significantly higher in AFX and PDS cases compared to all other analyzed rare skin cancer types. As expected, TEG values were low in DFSP and KS, while MCC cases exhibited intermediate TEG values. (4) Conclusions: High cumulative UV exposure is more strongly associated with AFX/PDS and MCC than with other rare skin cancers. These important results expand the available data associated with rare skin cancers while also offering insight into the value of differentiating among these tumor types based on their relationship with sun exposure, potentially informing preventative, diagnostic and/or therapeutic approaches. [ABSTRACT FROM AUTHOR]

Background: Primary ureteral neoplasms are extremely rare in dogs, and ureteral involvement usually occurs owing to the invasion of renal and bladder tumors. Case Description: This case report describes a 12-year-old intact male mixed-breed dog referred to a private clinic with a six-month history of abdominal distention. A physical examination revealed mild abdominal pain. Hematological tests detected normocytic-normochromic anemia (hematocrit 33.6% [reference interval-RI: 37%-55%], red blood cells 4.93 M/µl [RI: 5.5-8.5 M/µl], and hemoglobin 12.4 g/dl [RI: 12-18.0 g/dl]). The results from the leukogram, thrombogram, renal, and hepatic panels were within the reference intervals for dogs. Abdominal ultrasonography revealed a cavitary mass measuring approximately 12 cm in diameter as the largest tumor in the left abdominal region over the left hepatic lobe or mesenteric site. Chest radiography did not reveal any metastasis. Therefore, the patient underwent exploratory laparotomy, during which the left ureter was found to be affected by a 12-cm mass that adhered to the left kidney. A unilateral left ureteronephrectomy was performed, and histology and immunohistochemistry (IHC) confirmed well-differentiated primary ureteral leiomyosarcoma. The patient survived for 130 days but died of lung metastasis. Conclusion: Ureteral leiomyosarcoma should be investigated and included in the list of differential diagnoses for primary ureteral neoplasms. Regardless of the therapeutic modality, the prognosis of ureteral leiomyosarcoma may be unfavorable, as shown in this report. [ABSTRACT FROM AUTHOR]