Gastrointestinal Mesenchymal Tumors Research Articles

The maximum transverse diameter: an effective indicator for predicting peroral en bloc retrieval rate of mesenchymal tumors after endoscopic resection.

Gastrointestinal mesenchymal tumors (GIMTs) are being increasingly resected under endoscopy. Large GIMTs cannot be completely retrieved through the mouth, but the cut-off diameter of peroral en bloc retrieval (PEBR) for GIMTs completely resected is still unknown. This study aimed to investigate the ability of maximum transverse diameter (MTD) to predict the PEBR rate of GIMTs after endoscopic resection (ER). We retrospectively reviewed all patients who underwent ER for upper GIMTs from January 2009 to August 2023. The MTD was measured according to the maximum transverse diameter of specimen immediately retrieved after ER. For the PEBR rate, the independent predictors and optimal cut-off value of MTD were determined by logistic regression analysis and the receiver operating characteristic (ROC) curve analysis. The potential significance of preoperative CT for the evaluation of MTD was also clarified. A total of 2032 patients were diagnosed with upper GIMTs after en bloc resection under endoscopy. The overall PEBR rate was 98.72% (2006/2032). The PEBR rate was 100% for 1943 GIMTs with MTD < 2.5cm, 85.71% (60/70) for GIMTs with 2.5cm but ≤ 3.0cm, and 15.79% (3/19) for GIMTs with MTD > 3.0cm, and these rates were significantly different (P < 0.01). In terms of the PEBR rate of GIMTs, the ROC curve revealed that the optimal cut-off MTD value was 3.0cm, and logistic regression analysis revealed that MTD > 3.0cm was an independent predictive factor (OR 71.07, 95% CI 9.14-552.43; P < 0.001). The MTD of CT was related to that of the resected specimen (r = 0.7149, P < 0.01), and CT underestimated the mean MTD of upper GIMTs by 0.17cm (95% CI 0.09-0.24, P < 0.01). MTD is an effective indicator for predicting the PEBR rate of GIMTs after ER. Resected specimens with MTD > 3.0cm could not be routinely retrieved en bloc. Preoperative CT is suitable for evaluating the MTD of GIMTs, but underestimates the mean MTD of upper GIMTs by 0.17cm.

Construction of an electrochemical aptamer-based sensors for rapid quantification of the anticancer drug imatinib in blood to improve drug bioavailability at microdoses

Imatinib (Ima), as a commonly used anticancer drug for the clinical treatment of leukemia and gastrointestinal mesenchymal stromal tumour, requires timely monitoring of patients' blood concentration to ensure efficacy while reducing complications and achieving precision medicine due to its narrow therapeutic window (1–5 μM) and the varying sensitivity and resistance of different patients to Ima. However, traditional assays are slow and cumbersome, so improved and innovative platforms for monitoring Ima in the clinic are necessary. In this work, a nanoporous electrochemical aptamer-based (E-AB) sensor was designed for the detection of Ima and imatinib mesylate (Ima-Mes) in blood. Apt-37, a high-affinity and conformationally variable aptamer, was screened by molecular docking simulation calculations and circular dichroism (CD) for the construction of the E-AB sensor. The sensor detected Ima and Ima-Mes in the range of 0.1 μM-1 mM, and the recoveries in spiked blood samples were in the range of 70.7 %-104.6 % and 74.8 %-113.9 %, respectively. The precision and accuracy of the E-AB sensor for measuring Ima-Mes concentration in blood was similar to the standard LC-MS method. These results demonstrate that the developed E-AB sensor is an effective tool for rapid monitoring of Ima and Ima-Mes in blood.

Exploring the heterogeneity of interstitial cells of Cajal and their properties in gastrointestinal mesenchymal tumors applying single-cell RNA sequencing analysis

BackgroundGastrointestinal mesenchymal stromal tumors (GISTs) are a group of intramural tumors that exhibit a wide range of morphologies. Dysfunction or loss of interstitial cells of Cajal (ICCs) is correlated with the disorders of gastrointestinal motility. At present, the characterization and molecular mechanisms underlying the role of ICCs in GIST are still not clear.MethodsThe GSE162115 dataset from Gene Expression Omnibus database was processed using Seurat package for quality control, data normalization, and cell clustering. Differential expression and functional enrichment analyses were performed using the FindAllMarkers function and clusterProfiler package. Cellular heterogeneity was assessed by CytoTRACE and potential regulatory mechanisms of ICCs in GISTs were investigated using SCENIC. Cellular communication was inferred and analyzed applying the CellChat package.ResultsEight clusters were identified based on 34,861 cells. Intra-tumor samples had a higher proportion of ICCs than peri-tumor. ICCs were related to cell cycle and glycolytic activity in intra-tumor samples, while those in peri-tumor samples were involved in immune response. Further analysis identified four ICC subgroups (subcluster 1–4), of which subcluster 3 showed the most typical stem cell properties and interacted with the rest of the cells through the MIF-CD74 (CD44) protein.ConclusionThis study analyzed the heterogeneity and stem cell properties of ICCs in GISTs, revealing the molecular mechanisms and potential therapeutic targets for GISTs.

A case of gastric granulosa cell tumor resected by endoscopic submucosal dissection.

Granular cell tumors, uncommon soft tissue growths, predominantly manifest in the subcutaneous and tongue areas, while those in the gastrointestinal tract are scarce and develop slowly. Patients typically show no distinct clinical symptoms and are hard to differentiate from gastrointestinal mesenchymal tumors, smooth muscle tumors, neural sheath tumors, and rhabdomyosarcomas using endoscopy. This paper details a case of a granular cell tumor in the stomach addressed through endoscopic submucosal dissection, focusing on its endoscopic attributes and clinicopathological traits.

Autologous liver transplantation for unresectable hepatobiliary malignancies in enhanced recovery after surgery model.

Ex vivo liver resection combined with autologous liver transplantation offers the opportunity to treat otherwise unresectable hepatobiliary malignancies and has been applied in clinic. The implementation of enhanced recovery after surgery (ERAS) program improves the outcome of surgical procedures. This is a retrospective single-center study including 11 cases of patients with liver cancer that underwent autologous liver transplantation and received ERAS: cholangiocarcinoma of the hilar region (n = 5), intrahepatic cholangiocarcinoma (n = 3), gallbladder cancer (n = 1), liver metastasis from colorectal cancer (n = 1), and liver metastasis from gastrointestinal mesenchymal tumor (n = 1). There were no deaths within 30 days and major complications occurred in two patients, and four patients were readmitted upon the first month after the surgery. Median hospital stay was 20 days (range 13-44) and median open diet was Day 4 (range 2-9) after surgery and median early post-operative activity was Day 5 (range 2-9) after surgery. In conclusion, autologous liver transplantation is feasible in the treatment of otherwise unresectable hepatobiliary malignancies, and our study showed favorable results with autologous liver transplantation in ERAS modality. ERAS modality provides a good option for some patients whose tumors cannot be resected in situ and offers a chance for rapid recovery.

Abstract 1767: Molecular subclassification of gastrointestinal stromal tumors by genomic backgrounds

Abstract Gastrointestinal stromal tumors (GISTs) are the most common gastrointestinal mesenchymal tumors. While about 10% of GISTs are known to be developed from the KIT or PDGFRA gain-of-function mutations, the rest, which is the majority of GISTs, is so-called as wild-type GISTs. There are attempts to make subclassification of wild-type GISTs in syndromic or non-syndromic group as promising for understanding of heterogeneity or treatment strategy. Genomic states of succinate dehydrogenase B (SDHB) and neurofibromatosis type 1 (NF1) have been raised as candidates for subclassification of wild-type GISTs. In this presentation, we will discuss our recent three cases of wild-type GISTs, carrying germline pathogenic variants in SDHB or NF1. Two cases with SDHB germline pathogenic variants showed stomach GISTs with good clinical course, the maintained performance status and long survival nevertheless of the recurrence. The other case with an NF1 germline pathogenic variant showed multiple GISTs in small intestine which was controlled surgically and the late onset of other clinical symptoms of NF1. These cases might clinically suggest potential prognostic and predictive markers in genomic alterations of SDHB or NF1 for the cases with wild-type GISTs. Citation Format: Hideki Yamamoto, Eiji Nakada, Seiji Kawano, Fumino Kato, Chika Fukano, Mashu Futagawa, Yusaku Urakawa, Risa Ohsumi, Sayaka Ueno, Hiroyuki Yanai, Akira Hirasawa. Molecular subclassification of gastrointestinal stromal tumors by genomic backgrounds [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1767.

Analysis of the diagnostic value of CT radiomics models in differentiating GIST and other mesenchymal tumors.

To analyze the diagnostic value of computed tomography (CT) radiomics models in differentiating gastrointestinal stromal tumors (GIST) and other mesenchymal tumors. A retrospective analysis of clinical data from 153 patients with pathologically confirmed gastrointestinal mesenchymal tumors treated in our hospital from July 2019 to March 2024 was conducted, including 107 cases of GIST, 18 cases of leiomyoma, and 28 cases of schwannoma. LASSO regression was used for feature selection. Logistic regression and Random Forest (RF) models were established based on selected features using machine learning algorithms, with the dataset divided into training (107 cases) and validation sets (46 cases) at a 7:3 ratio. The diagnostic performance of the models was evaluated using receiver operating characteristic (ROC) curves. In the training set, there were significant differences between GIST and non-GIST in terms of enhancement degree, age, maximum diameter, and tumor location distribution (P<0.05). A total of 180 radiomics features were extracted using A.K software. LASSO regression reduced the high-dimensional data to 13 radiomics features. Logistic regression and RF models were established based on these 13 features. The AUC for the Logistic regression model was 0.753 in the training set and 0.582 in the validation set, while the AUC for the RF model was 0.941 in the training set and 0.746 in the validation set. The RF model showed higher diagnostic performance than the Logistic regression model (P<0.05). Decision curve analysis showed that the net benefit of the RF model in differentiating GIST was superior to classifying all patients as either GIST or non-GIST and also superior to the Logistic regression model within a probability threshold range of 20%-90%. The machine learning models based on radiomics features have good diagnostic value in predicting the pathological classification of GIST and other mesenchymal tumors, with the RF model showing superior diagnostic value compared to the Logistic regression model.

KIT-SNAP-tag/cell membrane chromatography model coupled with liquid chromatography-mass spectrometry for anti-GIST compound screening from Evodia rutaecarpa.

Gastrointestinal mesenchymal tumors, as the most common mesenchymal tumors in the gastrointestinal tract, are adjuvantly treated with multi-targeted tyrosine kinase inhibitors, such as imatinib and sunitinib, but there are problems of drug resistance and complex methods of monitoring therapeutic agents. The pathogenesis of this disease is related to mutations in tyrosine kinase (KIT) or platelet-derived growth factor receptor α, an important target for drug therapy. In recent years, the screening of relevant tyrosine kinase inhibitors from traditional Chinese medicine has become a hotspot in antitumor drug research. In the current study, the KIT-SNAP-tag cell membrane chromatography (KIT-SNAP-tag/CMC) column was prepared with satisfying specificity, selectivity, and reproducibility by chemically bonding high KIT expression cell membranes to thesilica gel surface using the SNAP-tag technology. The KIT-SNAP-tag/CMC-HPLC-MS two-dimensional coupling system was investigated using the positive drug imatinib, and the results showed that the system was a reliable model for screening potential antitumor compounds from complex systems. This system screened and identified three potential active compounds of evodiamine (EVO), rutaecarpin (RUT), and dehydroevodiamine (DEVO), which possibly target the KIT receptor, from the alcoholic extract of the traditional Chinese medicine Evodia rutaecarpa. Then, the KD values of the interaction of EVO, RUT, and DEVO with KIT receptors measured using nonlinear chromatography were 7.75 (±4.93) × 10-6, 1.42 (±0.71) × 10-6, and 2.34 (±1.86) × 10-6 mol/L, respectively. In addition, themethyl thiazolyl tetrazolium assay validated the active effects of EVO and RUT in inhibiting the proliferation of high KIT-expressing cells in the ranges of 0.1-10 µmol/L and 0.1-50 µmol/L, respectively. In conclusion, the KIT-SNAP-tag/CMC could be a reliable model for screening antitumor components from complex systems.

Surgery plus TKIs therapy for gastrointestinal stromal tumors

Abstract Introduction In this era of tyrosine kinase inhibitors (TKIs), the clinical benefit of surgery for patients with metastatic or recurrent gastrointestinal mesenchymal tumor (GIST) is not well defined. The aim of our study was to demonstrate the survival advantage of adding surgery in patients with recurrent or metastatic GIST. Methods A systematic search of PubMed, Web of Knowledge, Ovid’s database was conducted. Relevant studies published by 31 July 2022 on the role of surgery in recurrent or metastatic GIST were identified. Research quality was assessed using the Newcastle-Ottawa Quality Assessment Scale. Results Eight studies involving 842 patients were included. The four included studies covered 3-year survival and included 441 patients, of whom 302 received TKIs, and 139 received TKIs plus surgery. 3-year overall survival was significantly higher in the TKIs plus surgery group than in the TKIs group (OR=2.37, 95% CI 1.45–3.88, P = 0.001). The 5-year overall survival was 69.0% in the TKIs plus surgery group compared with 49.1% in the TKIs only group. Survival was significantly higher in TKIs plus surgery group (OR = 2.69, 95%Cl 1.49–4.86, P=0.001). Four studies, including 453 patients, indicated 3-year progression-free survival (PFS). The pooled analysis revealed the TKIs plus surgery group did have a better PFS than the TKIs only group (OR = 4.02, 95% CI: 1.45–11.16, P=0.008). Three included studies focused on gastrointestinal stromal tumor liver metastasis (GLM). The role of surgery plus TKIs had statistically significant better 5-year overall survival as compared with TKI treatment alone (OR = 2.34, 95% Cl 1.30–4.22, P=0.005). Conclusions Treatment with surgical resection and TKIs could significantly improve the prognosis of patients with recurrent or metastatic GIST.

Factors associated with gastrointestinal stromal tumor rupture and pathological risk: A single-center retrospective study.

Gastrointestinal stromal tumor (GIST) is a rare gastrointestinal mesenchymal tumor with potential malignancy. Once the tumor ruptures, regardless of tumor size and mitotic number, it can be identified into a high-risk group. It is of great significance for the diagnosis, treatment, and prognosis of GIST if non-invasive examination can be performed before surgery to accurately assess the risk of tumor. To identify the factors associated with GIST rupture and pathological risk. A cohort of 50 patients with GISTs, as confirmed by postoperative pathology, was selected from our hospital. Clinicopathological and computed tomography data of the patients were collected. Logistic regression analysis was used to evaluate factors associated with GIST rupture and pathological risk grade. Pathological risk grade, tumor diameter, tumor morphology, internal necrosis, gas-liquid interface, and Ki-67 index exhibited significant associations with GIST rupture (P < 0.05). Gender, tumor diameter, tumor rupture, and Ki-67 index were found to be correlated with pathological risk grade of GIST (P < 0.05). Multifactorial logistic regression analysis revealed that male gender and tumor diameter ≥ 10 cm were independent predictors of a high pathological risk grade of GIST [odds ratio (OR) = 11.12, 95% confidence interval (95%CI): 1.81-68.52, P = 0.01; OR = 22.96, 95%CI: 2.19-240.93, P = 0.01]. Tumor diameter ≥ 10 cm, irregular shape, internal necrosis, gas-liquid interface, and Ki-67 index ≥ 10 were identified as independent predictors of a high risk of GIST rupture (OR = 9.67, 95%CI: 2.15-43.56, P = 0.01; OR = 35.44, 95%CI: 4.01-313.38, P < 0.01; OR = 18.75, 95%CI: 3.40-103.34, P < 0.01; OR = 27.00, 95%CI: 3.10-235.02, P < 0.01; OR = 4.43, 95%CI: 1.10-17.92, P = 0.04). Tumor diameter, tumor morphology, internal necrosis, gas-liquid, and Ki-67 index are associated with GIST rupture, while gender and tumor diameter are linked to the pathological risk of GIST. These findings contribute to our understanding of GIST and may inform non-invasive examination strategies and risk assessment for this condition.

Newly developed endoscopic retrieval device: funnel-shaped overtube formed by air inflation-deflation.

Techniques for endoscopic retrieval require further development. Traditional measures using nets, grasping forceps, and overtubes [1] are sometimes inadequate for retrieval of large, endoscopically resected specimens or sharp foreign bodies with a potential risk of perforation. Although new alternatives include plastic [2], laparoscopic [3], and commercially available bags [4], reliable retrieval of solid gastrointestinal mesenchymal tumors (GIMTs) during endoscopic full-thickness resection is still being investigated. Based on our previously published concept [5], we have developed a novel retrieval device, a funnel-shaped overtube formed by air inflation–deflation (Fuji Systems, Tokyo, Japan). We here report a successful animal experiment in which the device achieved retrieval of press-through package (PTP) sheets and simulated gastric GIMTs ([Video 1]).

Prevalence of CKIT and PDGFRA Mutation in Gastrointestinal Stromal Tumors among Filipinos

Background: Gastrointestinal stromal tumors (GIST) is defined as specific, typically kit (CD117)-positive and CKIT or platelet-derived growth factor receptor alpha (PDGFRA) mutation-driven mesenchymal tumors that can occur anywhere in the GI tract. GIST diagnosis relies heavily on immunohistomorphology. However, with the advent of molecular testing, the classification, diagnosis and targeted-therapy for gastrointestinal mesenchymal tumors have been greatly improved. In the Philippines, molecular testing is not yet readily available as in other countries. The local molecular profile of gastrointestinal stromal tumors is a point of investigation as treatment may be more tailored to the patients’ needs. Objective: This study aims to determine the prevalence of CKIT and PDGFRA mutations among formalin-fixed and paraffin embedded gastrointestinal stromal tumors and other gastrointestinal mesenchymal tumors in St. Luke’s Medical Center – Quezon City. Methods: A retrospective cross-sectional study of formalin fixed and paraffin embedded tumor samples diagnosed as Gastrointestinal Stromal Tumor from January 1, 2009 to December 31, 2017 will be analyzed for KIT and PDGFRA mutations. Result: The epidemiology of GIST remains constant in that mean age group is the 5th to 6th decade, with equal gender distribution, and stomach followed by small bowel are the most common sites. Mutational analysis of the GISTs showed predominantly KIT Exon 11 (47.83%) followed by CKIT Exon 9 (13.04%) and PDGFRA Exon 18 (10.87%). For KIT Exon 11, deletion is the most common mutations followed by point mutations. No mutation is detected in 47.83% of GISTs. Conclusion:&nbsp;Mutational analysis for CKIT-PDGFRA is warranted among GIST patients, as it may significantly influence treatment protocol in our patients.

S3609 Gastric Schwannoma in a Patient With Early Satiety

Introduction: Schwannomas are an uncommon subtype of benign gastrointestinal mesenchymal tumor found most frequently in the stomach originating from the Auerbach myenteric nerve plexus. Gastric schwannoma is frequently mistreated as it shares many similarities with GIST. We present the case of a patient with early satiety and iron deficiency anemia who was found to have gastric schwannoma on upper endoscopy. Case Description/Methods: A 59-year-old female with endometriosis and iron deficiency anemia on oral iron supplementation presented to our clinic with complaints of fatigue, frequent post-prandial cough, early satiety, and dark stools. She reported chronic NSAID use and denied abdominal pain, dysphagia, nausea, and unexplained weight loss. Initial CBC demonstrated a hemoglobin of 9.2 g/dL with positive stool guaiac testing. Cessation of NSAIDs led to hemoglobin improvement within normal limits. EGD revealed a roughly 5 cm smooth submucosal mass in the distal gastric body along the greater curvature with firm consistency and a central depression (Figure A). Colonoscopy was unremarkable. Abdominal CT demonstrated an exophytic mass within the gastric wall with relatively homogenous attenuation and enhancement (Figure B). Endoscopic ultrasound with FNA of the mass revealed pathology suspicious for a stromal cell neoplasm and elective laparoscopic partial gastrectomy was performed with findings of a 4.7 x 3.7 x 3.6 cm submucosal mass consistent with schwannoma with Sox10/S100 positivity and DOG-1/c-KIT negativity. The patient resumed a normal diet 2 days after surgery without complications. Discussion: Gastric schwannoma is frequently misdiagnosed as GIST due to similar prevalence, clinical symptoms, and appearance. Some studies suggest a misdiagnosis rate of up to 96.7%. Key to the diagnosis is the presence of S-100 positivity in schwannoma as GIST is negative for this marker. Additionally, DOG-1 and c-KIT are markers positive in GIST but negative in schwannoma. Most gastrointestinal schwannomas are solitary with sizes ranging from < 1 cm to 28 cm. Endoscopic ultrasound with FNA biopsy is recommended to increase chances of preoperative diagnosis by approximately 10%. Treatment modalities vary based on tumor size, with endoscopic resection suggested for tumors < 3 cm in diameter and surgical excision for larger sized masses. Malignant transformation is extremely rare occurring in roughly 2% of cases with S-100 expression decreasing as dedifferentiated Schwann cells form.Figure 1.: A. Endoscopic appearance of schwannoma as a smooth exophytic submucosal mass with central depression seen along the greater curvature of distal gastric body. B. Abdominal CT demonstrating luminal compression of the gastric body by a schwannoma with relatively homogenous attenuation and enhancement.

S3595 Gastric Glomus Tumors: Silent Until Ulcerated

Introduction: Glomus tumors are rare and mostly benign mesenchymal neoplasms comprising fewer than 2% of all soft tissue tumors. They arise from the modified smooth muscle cells (glomus cells) of the glomus body, an arteriovenous shunt typically found in peripheral soft tissue of the extremities. Rarely, glomus tumors can occur in the gastrointestinal (GI) tract, where they arise from the submucosa or muscularis propria. We present two interesting cases of gastric glomus tumor (GGT) with different clinical outcomes. Case Description/Methods: A 46-year-old female presented with shortness of breath and fatigue for 3 months. Labs showed iron deficiency anemia with a hemoglobin of 4.4 gm/dl. Esophagogastroduodenoscopy (EGD) revealed a large, ulcerated, partially circumferential mass in the gastric (Figure 1A, 1B) Imaging showed a solid 7.8 cm mass in the gastric antrum with multiple hepatic metastases. Gastric biopsy showed glomus tumor, with a positive smooth muscle actin (SMA) stain and abundant background necrosis. Liver biopsy also confirmed metastasis of the glomus tumor. Patient is currently undergoing chemotherapy to downsize the primary tumor before surgical intervention. A 72-year-old female with a history of breast cancer was admitted with hematemesis and melena. EGD revealed a large submucosal ulcerated gastric mass with signs of bleeding. Endoscopic ultrasound (EUS) showed the mass was arising from the muscularis propria, in the antrum of the stomach (Figure 2A, 2B) Fine needle aspiration was performed which expressed only synaptophysin (Syn), suggestive of gastric neuroendocrine tumor. Patient underwent an exploratory laparotomy and distal gastrectomy for continued GI bleeding. The tumor was sent for surgical pathology, which expressed both smooth muscle actin and Syn, confirming glomus tumor. The patient was stable following gastrectomy. Discussion: GGTs account for approximately 1% of all GI mesenchymal tumors and are difficult to differentiate from other richly vascularized tumors, such as gastrointestinal stromal tumor (GIST). The definitive diagnosis relies on EGD, histopathologic examination with immunohistochemical staining and EUS-guided fine-needle aspiration. Glomus tumor cells stain positive for SMA and vimentin, while Syn and CD34 can be positive in some cases. Surgical resection is the treatment of choice and offers a favourable prognosis. Metastatic spread as seen in one of our cases is extremely rare. There are no standard of care chemotherapeutic regimens for treatment of GGTs.Figure 1.: Two gastric glomus tumors seen on esophagogastroduodenoscopy (EGD) and endoscopic ultrasound (EUS).

An Unusual Stomach Tumour: Plexiform Angiomyxoid Fibroma Stomach-A Case Report.

Plexiform angiomyxoid myofibroblast tumour (PAMT) is a rare mesenchymal tumour of the stomach. To date, about 45 cases of PAMT have been reported in the literature. This is an extremely rare mesenchymal gastric tumour with definite histological pattern and is a tumour typified by spindle cells with myofibroblast characteristics. A 70-year-old woman was admitted with vague upper abdominal pain and dyspepsia and on OGD was found to have a polypoidal lesion with ulceration on the posterior wall of the body of the stomach towards the greater curvature. The endoscopy biopsy suggested the above diagnosis. The patient was investigated with CT scan and CT showed a large nodular growth 10 × 8cm with pancreatic tail involvement and splenic involvement. The patient was treated with multi-visceral resection and favourable outcome was achieved. This entity of PAMT was a histological rarity anda technically challenging case and hence was analysed and presented. PAMT is a rare mesenchymal tumour of the stomach and is characterised by spindle cells with myofibroblast characteristics with a potential to differentiate towards smooth muscle cells. These tumours have a benign course and rarely can have an infiltrative behaviour. PAMT of the stomach is a very rare mesenchymal tumour with a unique histological appearance, and it needs to be distinguished from GIST and other gastrointestinal mesenchymal tumours, although extra gastric extension and vascular invasion are sometimes observed. Here, we are reporting this case as a case of PAMT arising from the body of the stomach which required multi-visceral resection.

Giant Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors in interstitial Cajal cells of myenteric plexus of the muscularis propria are the commonest gastrointestinal mesenchymal tumors, not exclusively, appearing in the stomach. This case report documents management of a giant gastric stromal tumor of a 75 year-old female patient presented with generalized, vague, constant abdominal pain and melena, both of a week’s duration. She had early satiety with dizziness, feeling weak, and fatigue. She had a good appetite and no weight loss, hematemesis, or vomiting. She was apyrexial, with normal vital signs. The abdomen was soft, with a palpable large mass in epigastrium and central abdomen; an abdominal CT showed a heterogeneous mass lesion of antrum of stomach. Subtotal gastrectomy with roux-en-y gastrojejunostomy was performed. Histopathology showed epithelioid high grade gastrointestinal stromal tumor. The cornerstone therapy is a full operative removal of the tumor, with adjuvant therapy with selective receptor tyrosine kinase inhibitors.

Circularity Is a Potential Noninvasive Diagnostic Indicator to Differentiate Gastric Submucosal Tumors

Background and Aims: Noninvasive, imaging diagnosis of gastrointestinal mesenchymal tumors (GIMTs) is still difficult. This study aimed to develop a novel diagnostic method of GIMTs via endoscopic ultrasonography (EUS) using circularity. Methods: In a derivation series, we retrospectively collected 50 GIMTs 2–5 cm in diameter of two institutions. After selecting one EUS still image showing the maximal area per lesion, two endoscopists who were blind to the histological diagnosis assessed circularity, a surrogate indicator of roundness (range, 0–1; 1 = a true circle), with an image-analyzing software. Median circularity of three types of GIMT was compared, and the cutoff value to differentiate a group from other groups was presented by drawing a receiver operating characteristic curve. Subsequently, we assessed the diagnostic ability of circularity in 91 GIMTs which were retrospectively collected from the other two institutions by using the optimal cutoff value presented in the derivation series. Results: The circularity in leiomyomas indicated 0.70 and was significantly lower than that of gastrointestinal stromal tumors (0.89), schwannomas (0.90), and their combined group. When leiomyomas were diagnosed as the circularity of <0.8305, which was presented as the optimal cutoff value, the diagnostic accuracy, sensitivity, and specificity in the validation series were 73.6%, 80.0%, and 72.4%, respectively. Conclusion: The data demonstrated that leiomyomas significantly exhibited more distortion than other GIMTs. That implies that the difference in shape, which is objectively determined as circularity, is useful to noninvasively discriminate leiomyomas from other GIMTs.

Value of 18F-FDG PET/CT for differentiating diagnosis between malignant and benign primary gastric gastrointestinal mesenchymal tumors: a single-center retrospective study.

Malignant primary gastric gastrointestinal stromal tumors (gGISTs) without treatment with imatinib are prone to bleeding and peritoneum implantation during operation. Therefore, preoperative assessment of the malignant potential of gGIST is essential. The use of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) combined with computed tomography (PET/CT) as a non-invasive tool for diagnosis, staging and prognosis evaluation in oncology, may also be useful for gGISTs. In the present study, we analyzed the value of 18F-FDG PET-CT in assessing the malignant potential of gGISTs before treatment. Patients who were diagnosed with gGIST by pathology and underwent 18F-FDG PET/CT at the same time were collected. The clinicopathological features of 26 patients with gGISTs were retrospectively analyzed at last. The gGIST risk classification was graded according to the US National Institutes of Health (NIH) GIST risk classification criteria [2008]. Lesions were classified as malignant group (moderate- or high-risk category) and benign group (low- or very low-risk category) according to pathology. The relationship between the maximal standard uptake value (SUVmax) and GIST risk category, tumor diameter, Ki-67 index, and mitotic count was analyzed. The cut-off level of SUVmax for the diagnosis of malignant gGIST with the highest sensitivity was calculated based on the receiver-operating characteristic (ROC) curve. The SUVmax, tumor diameter, Ki-67 index, and mitotic count of the 26 gGIST patients were 5.90±4.49, 7.40±4.92 cm, 7.62%±11.76%, (5.96±3.19)/50 high-power field (HPF), respectively. SUVmax was significantly correlated with GIST risk category, Ki-67 index, and mitotic count (r=0.855, 0.860, and 0.690, all P<0.01) but not with tumor diameter (r=0.383, P=0.054). The SUVmax of gGIST was 7.00±4.57 in the malignant group (moderate or high NIH risk category in 20 patients), which was significantly different from that (2.25±0.77) in the benign group (low or extremely low NIH risk category in 6 patients) (t=4.566, P<0.01). ROC curve analysis showed that a SUVmax cut-off of 2.60 was most sensitive for predicting malignant gGIST. When the area under the curve was 0.967, the sensitivity was 100% and the specificity was 83.3%. SUVmax may be used as a complementary indicator for predicting the malignant potential of gGISTs before treatment.

Laparoscopic treatment of a series of rare tumors, gastric schwannoma with chronic iron deficiency anemia: A case report.

Introduction and importanceGastric schwannoma is a rare and slow-growing gastrointestinal mesenchymal tumor. Gastric neurilemmoma accounts for less than 1% of all gastric tumors. Without specific clinical manifestations, it is easy to be misdiagnosed before the operation, and rupture and bleeding will lead to persistent anemia in patients. The diagnosis can only be confirmed by pathological examination.Case presentationA 55-year-old woman was admitted to The Second Hospital of Lanzhou University due to abdominal distension, pain, acid regurgitation, and belching. The tumor was completely removed by laparoscopy. The postoperative specimens were diagnosed as gastric neurilemmoma by pathological examination.Clinical discussionSchwannoma is a benign neurogenic tumor. Complete surgical resection with a negative cutting edge is an effective method for the treatment of gastric schwannoma. Because the lesion is benign, the prognosis of the patient is good.ConclusionLaparoscopic tumor resection is a choice for the treatment of gastric schwannoma, and the therapeutic effect is good.

Differentiating Gastrointestinal Stromal Tumors from Leiomyomas Using a Neural Network Trained on Endoscopic Ultrasonography Images

Background: Endoscopic ultrasonography (EUS) is crucial to diagnose and evaluate gastrointestinal mesenchymal tumors (GIMTs). However, EUS-guided biopsy does not always differentiate gastrointestinal stromal tumors (GISTs) from leiomyomas. We evaluated the ability of a convolutional neural network (CNN) to differentiate GISTs from leiomyomas using EUS images. The conventional EUS features of GISTs were also compared with leiomyomas. Patients and Methods: Patients who underwent EUS for evaluation of upper GIMTs between 2010 and 2020 were retrospectively reviewed, and 145 patients (73 women and 72 men; mean age 54.8 ± 13.5 years) with GISTs (n = 109) or leiomyomas (n = 36), confirmed by immunohistochemistry, were included. A total of 978 images collected from 100 patients were used to train and test the CNN system, and 384 images from 45 patients were used for validation. EUS images were also evaluated by an EUS expert for comparison with the CNN system. Results: The sensitivity, specificity, and accuracy of the CNN system for diagnosis of GIST were 92.0%, 64.3%, and 86.98% for the validation dataset, respectively. In contrast, the sensitivity, specificity, and accuracy of the EUS expert interpretations were 60.5%, 74.3%, and 63.0%, respectively. Concerning EUS features, only higher echogenicity was an independent and significant factor for differentiating GISTs from leiomyomas (p < 0.05). Conclusions: The CNN system could diagnose GIMTs with higher accuracy than an EUS expert and could be helpful in differentiating GISTs from leiomyomas. A higher echogenicity may also aid in differentiation.