Endoscopic ultrasound-guided fine needle tissue acquisition biopsy samples do not allow a reliable proliferation assessment of gastrointestinal stromal tumours

Endoscopic management of subepithelial lesions including neuroendocrine neoplasms: European Society of Gastrointestinal Endoscopy (ESGE) Guideline

1: ESGE recommends endoscopic ultrasonography (EUS) as the best tool to characterize subepithelial lesion (SEL) features (size, location, originating layer, echogenicity, shape), but EUS alone is not able to distinguish among all types of SEL.Strong recommendation, moderate quality evidence. 2: ESGE suggests providing tissue diagnosis for all SELs with features suggestive of gastrointestinal stromal tumor (GIST) if they are of size > 20 mm, or have high risk stigmata, or require surgical resection or oncological treatment.Weak recommendation, very low quality evidence. 3: ESGE recommends EUS-guided fine-needle biopsy (EUS-FNB) or mucosal incision-assisted biopsy (MIAB) equally for tissue diagnosis of SELs ≥ 20 mm in size.Strong recommendation, moderate quality evidence. 4: ESGE recommends against surveillance of asymptomatic gastrointestinal (GI) tract leiomyomas, lipomas, heterotopic pancreas, granular cell tumors, schwannomas, and glomus tumors, if the diagnosis is clear.Strong recommendation, moderate quality evidence. 5: ESGE suggests surveillance of asymptomatic esophageal and gastric SELs without definite diagnosis, with esophagogastroduodenoscopy (EGD) at 3-6 months, and then at 2-3-year intervals for lesions < 10 mm in size, and at 1-2-year intervals for lesions 10-20 mm in size. For asymptomatic SELs > 20 mm in size that are not resected, ESGE suggests surveillance with EGD plus EUS at 6 months and then at 6-12-month intervals.Weak recommendation, very low quality evidence. 6: ESGE recommends endoscopic resection for type 1 gastric neuroendocrine neoplasms (g-NENs) if they grow larger than 10 mm. The choice of resection technique should depend on size, depth of invasion, and location in the stomach.Strong recommendation, low quality evidence. 7: ESGE suggests considering removal of histologically proven gastric GISTs smaller than 20 mm as an alternative to surveillance. The decision to resect should be discussed in a multidisciplinary meeting. The choice of technique should depend on size, location, and local expertise.Weak recommendation, very low quality evidence. 8: ESGE suggests that, to avoid unnecessary follow-up, endoscopic resection is an option for gastric SELs smaller than 20 mm and of unknown histology after failure of attempts to obtain diagnosis.Weak recommendation, very low quality evidence. 9: ESGE recommends basing the surveillance strategy on the type and completeness of resection. After curative resection of benign SELs no follow-up is advised, except for type 1 gastric NEN for which surveillance at 1-2 years is advised.Strong recommendation, low quality evidence. 10: For lower or upper GI NEN with a positive or indeterminate margin at resection, ESGE recommends repeating endoscopy at 3-6 months and another attempt at endoscopic resection in the case of residual disease.Strong recommendation, low quality evidence.

Use of Artificial Intelligence in the Prediction of Malignant Potential of Gastric Gastrointestinal Stromal Tumors

BACKGROUND AND AIMS

This study aimed to investigate whether AI via a deep learning algorithm using endoscopic ultrasonography (EUS) images could predict the malignant potential of gastric gastrointestinal stromal tumors (GISTs).

METHODS

A series of patients who underwent EUS before surgical resection for gastric GISTs were included. A total of 685 images of GISTs from 55 retrospectively included patients were used as the training data set for the AI system. Convolutional neural networks were constructed to build a deep learning model. After applying the synthetic minority oversampling technique, 70% of the generated images were used for AI training and 30% were used to test AI diagnoses. Next, validation was performed using 153 EUS images of 15 patients with GISTs. In addition, conventional EUS features of 55 patients in the training cohort were evaluated to predict the malignant potential of GISTs and mitotic index.

RESULTS

The overall sensitivity, specificity, and accuracy of the AI system for predicting malignancy risk were 83%, 94%, and 82% in the training dataset, and 75%, 73%, and 66% in the validation cohort, respectively. When patients were divided into low-risk and high-risk groups, sensitivity, specificity, and accuracy increased to 99% in the training dataset and 99.7%, 99.7%, and 99.6%, respectively, in the validation cohort. No conventional EUS features were found to be associated with either malignant potential or mitotic index (P > 0.05).

CONCLUSIONS

AI via a deep learning algorithm using EUS images could predict the malignant potential of gastric GISTs with high accuracy.

Mitotic count of fine needle aspiration material of gastrointestinal stromal tumours of the stomach underestimates actual mitotic count

INTRODUCTION

A mitotic count is required for histological grading in resections of gastrointestinal stromal tumours (GISTs). However, no consensus on the utility of mitotic count in fine needle aspiration (FNA) GIST material currently exists. This study examines the relationship between mitotic counts of FNAs and subsequent resections of GISTs of the stomach.

MATERIALS AND METHODS

We identified 39 cases of GISTs of the stomach diagnosed via FNA at our institution between January 1, 2014, and December 31, 2019, with subsequent resection. We noted if rapid on-site evaluation (ROSE) was performed. Cell block (CB) material from FNAs was analysed for total area, percentage containing neoplastic cells, and number of mitoses. We compared the mitotic counts in CBs and subsequent resections with t tests.

RESULTS

ROSE was performed in 82% of cases and called adequate every time. Mean values for total CB area, neoplastic material percentage, and area of neoplastic cells were 54.7 mm² (range 1-986), 45% (range 10%-90%), and 19.2 mm² , respectively; 27 cases (69%) had greater than 50 high powered fields of GIST material in the CB. Mean numbers of mitoses per 5 mm² were 0.38 (range 0-11) for CBs versus 5.92 (range 0-70) for resections (P < 0.05).

CONCLUSION

At our institution, ROSE adequacy of spindle cell lesions focuses on diagnosing GIST rather than obtaining adequate material for histological grading. Mitotic figures were statistically lower in FNA CB material than subsequent resections, and using mitotic counts from CB material may underestimate the histological grade of GISTs of the stomach.

Correlation of Endoscopic Ultrasonography Features with the Mitotic Index in 2- to 5-cm Gastric Gastrointestinal Stromal Tumors

BACKGROUND

Predicting the malignancy potential of gastrointestinal stromal tumor (GIST) before resection could improve patient management strategies as gastric GISTs with a low malignancy potential can be safely treated endoscopically, but surgical resection is required for those tumors with a high malignancy potential. This study aimed to evaluate endoscopic ultrasound (EUS) features of 2- to 5-cm gastric GISTs that might be used to predict their mitotic index using surgical specimens as the gold standard.

PATIENTS AND METHODS

Forty-nine patients (30 females and 19 males; mean age 55.1 ± 12.7 years) who underwent EUS examinations, followed by surgical resections of 2- to 5-cm gastric GISTs, were retrospectively reviewed.

RESULTS

The mean tumor size was 3.44 ± 0.97 (range 2.1-5.0) cm. A univariate analysis revealed no significant differences in age, sex, and tumor location in the low mitotic index and high mitotic index groups (all p > 0.05). In terms of EUS features, there were no significant differences in the mitotic indexes with respect to the shape, surface lobulation, border regularity, echogenicity, homogeneity, growth patterns, presence of mucosal ulceration, hyperechogenic foci, anechoic spaces, and hypoechoic halos (all p > 0.05). However, the tumor size was larger in the high mitotic index group than that in the low mitotic index group (3.97 ± 1.05 vs. 3.27 ± 0.9 cm, p = 0.03).

CONCLUSION

Conventional EUS features are not reliable for predicting the mitotic index of 2- to 5-cm gastric GISTs. Further modalities for predicting the mitotic index are needed to prevent unnecessary surgical resections in patients with a low risk of malignancy.

Evaluation of Ki67 Index in Endoscopic Ultrasound-Guided Fine Needle Aspiration Samples for the Assessment of Malignancy Risk in Gastric Gastrointestinal Stromal Tumors

BACKGROUND

The risk of malignancy in resected gastrointestinal stromal tumors (GISTs) depends on tumor size, location, and mitotic index. Reportedly, the Ki67 index has a prognostic value in resected GISTs. We aimed to analyze the accuracy of endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) samples with reference to Ki67 index, using surgical specimens as the gold standard.

METHODS

Fifty-five patients who underwent EUS-FNA followed by surgical resection for gastric GISTs were retrospectively analyzed. Patients' age and sex; tumors' size and location; mitotic index, cell type, cellularity, pleomorphism, presence of ulceration, hemorrhage, necrosis, mucosal or serosal invasion, growth pattern, and Ki67 index based on pathology were investigated.

RESULTS

Location in fundus, ulceration, hemorrhage, mucosal invasion, and Ki67 index in surgical specimens were significant in predicting high-risk groups (p < 0.05) on univariate analysis. Frequency of bleeding (p = 0.034) and the Ki67 index (p = 0.018) were the only independent significant factors in multivariate analysis. The optimal cutoff level of Ki67 was 5%, with 88.2% sensitivity and 52.8% specificity (p = 0.021). The mean Ki67 index was lower in EUS-FNA samples than in surgical specimens (2% [1-15] versus 10% [1-70], p = 0.001). The rank correlation coefficient value of Ki67 was 0.199 (p = 0.362) between EUS-FNA and surgical samples and showed no reliability for EUS-FNA samples.

CONCLUSION

The Ki67 index in resected specimens correlated with high-risk GISTs, although it had no additive value to the current criteria. The Ki67 index in EUS-guided FNA samples is not a reliable marker of proliferation in GISTs.

Gastric gastrointestinal stromal tumor with predominant cystic formation diagnosed by endoscopic ultrasound-fine needle aspiration

A 69-year-old woman who had no symptoms was found to have an intraperitoneal tumor on abdominal ultrasonography in a medical checkup. Thereafter, she was referred to our hospital for a further detailed examination. Contrast-enhanced computed tomography revealed a thin-walled cystic tumor with a diameter of 8 cm and with a hypervascular solid masses in the cystic wall, along with intraperitoneal multiple nodules. The cystic tumor was contiguous with the stomach wall. For solid mass of cystic lesions, endoscopic ultrasound-fine needle aspiration was performed transgastrically with a 25-gauge Franseen needle. Pathologically, the cells in the tumor were spindle shaped with atypical nucleus and were positive for c-kit, CD34, and smooth muscle actin. The tumor was diagnosed as gastrointestinal stromal tumor (GIST). With the diagnosis of gastric GIST with peritoneal dissemination, imatinib chemotherapy was initiated.

Atypical presentation of a gastric stromal tumor masquerading as a giant intraabdominal cyst: A case report

Gastrointestinal stromal tumors (GISTs) are mesenchymal neoplasms that arise in the gastrointestinal tract, accounting for ~1% of gastric malignancies. The present study reports the case of a GIST of the stomach in a 75-year-old man who presented with abdominal distension and anorexia for 1 month. Gastroscopy was unremarkable. Ultrasound and computed tomography (CT) scans showed a giant intraabdominal cystic lesion of unknown origin. The lesion was initially believed to be a duplication cyst, a pancreatic pseudocyst or a liver cyst in the pre-operative diagnosis. Exploratory laparotomy revealed a cystic lesion of the lesser sac originating from the lesser curvature of the stomach. A distal gastrectomy with en bloc resection of the lesion was performed. The intraoperative frozen section showed a spindle-cell GIST and microscopically negative margins. The patient was treated with imatinib for 1 year. The latest CT scan at 14 months post-surgery did not show any recurrence. Although GISTs presenting as predominantly cystic lesions are very rare, they should be considered in the differential diagnosis of cystic lesions of the upper abdomen.

Syndromic gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of gastrointestinal tract. They feature heterogeneous triggering mechanisms, implying relevant clinical differences. The vast majority of GISTs are sporadic tumors. Rarely, however, GIST-prone syndromes occur, mostly depending on heritable GIST predisposing molecular defects involving the entire organism. These conditions need to be properly identified in order to plan appropriate diagnostic, prognostic and therapeutic procedures. Clinically, GIST-prone syndromes must be thought of whenever GISTs are multiple and/or associated with accompanying signs peculiar to the background tumorigenic trigger, either in single individuals or in kindreds. Moreover, syndromic GISTs, individually considered, tend to show distinctive features depending on the underlying condition. When applicable, genotyping is usually confirmatory. In GIST-prone conditions, the prognostic features of each GIST, defined according to the criteria routinely applied to sporadic GISTs, combine with the characters proper to the background syndromes, defining peculiar clinical settings which challenge physicians to undertake complex decisions. The latter concern preventive therapy and single tumor therapy, implying possible surgical and molecularly targeted options. In the absence of specific comprehensive guidelines, this review will highlight the traits characteristic of GIST-predisposing syndromes, with particular emphasis on diagnostic, prognostic and therapeutic implications, which can help the clinical management of these rare diseases.

Unusual focal keratin expression in plexiform angiomyxoid myofibroblastic tumor: A case report and review of the literature

BACKGROUND

Plexiform angiomyxoid myofibroblastic tumor (PAMT), also known as plexiform fibromyxoma, is a rare distinctive benign intramural tumor, typical of gastric antrum, commonly causing mucosal ulceration with upper gastrointestinal bleeding and anemia, effectively treated by complete surgical resection usually accomplished by distal gastrectomy.

METHODS AND RESULTS

We herein report a 47-year-old man presenting with a syncopal episode, regurgitation and epigastric discomfort, bearing a gastric antral myxoid plexiform tumor positive for α-smooth muscle actin, vimentin and, partially, for caldesmon, desmin, and CD10; CD117, DOG1, CD34, S100, CAM5.2, CK20, CK7, EMA, p53, CDX2, chromogranin A, synaptophysin, anaplastic lymphoma kinase, Melan-A, and HMB-45 were all negative. All these features are typical of PAMT. Of note, focal positivity for AE1/AE3 and pan-CK KL1 was also present.

CONCLUSIONS

The finding of a focal keratin expression in PAMT contributes to enlarge the immunophenotypic spectrum of this tumor type and is relevant for avoiding presurgical misdiagnoses which could ultimately lead to inappropriate overtreatment of patients with PAMT.

Feasibility and Diagnostic Yield of Endoscopic Ultrasonography-Guided Fine Needle Biopsy With a New Core Biopsy Needle Device in Patients With Gastric Subepithelial Tumors

As treatment decisions for patients with gastric subepithelial tumors (SETs) largely depend on the histopathologic diagnosis, noninvasive and effective tissue acquisition methods are definitely required for proper management of gastric SETs. Recently, a new endoscopic ultrasonography-guided fine needle biopsy (EUS-FNB) device with ProCore reverse bevel technology was developed. We aimed to elucidate the feasibility and diagnostic yield of EUS-FNB with this new core biopsy needle device in patients with gastric SETs. A prospectively maintained database was retrospectively reviewed to identify consecutive patients who underwent EUS-FNB with a 22-gauge ProCore needle for gastric SETs 2 cm or larger. The main outcome measurement was the diagnostic yield of EUS-FNB. Procedure results were categorized into diagnostic, suggestive, or nondiagnostic. Of the 43 patients, needle punctures were successful in all cases irrespective of tumor location. EUS-FNB procedure results were diagnostic in 86.0%, suggestive in 4.7%, and nondiagnostic in 9.3% of cases, respectively. The diagnostic yield was the highest in fundus (100.0%), followed by body (89.5%), cardia (83.3%), and antrum (50.0%). All 18 patients with cardiac SET were finally diagnosed to have leiomyoma, and 16 patients with diagnostic or suggestive results avoided surgery. A heterogeneous echo pattern on EUS was found in 33.3% of cases with nondiagnostic or suggestive results and in 5.4% with diagnostic results. In multivariate analysis, no independent predictor of unsuccessful EUS-FNB with nondiagnostic or suggestive results was identified. Agreement between EUS-FNB and surgical pathology was 100% with respect to the diagnosis of gastrointestinal stromal tumor. However, there was a significant discrepancy in mitotic counts observed between the EUS-FNB and surgical specimens in patients with gastrointestinal stromal tumor. There were no significant procedure-related adverse events during and after the procedures. EUS-FNB with a 22G ProCore needle is a technically feasible, safe, and effective procedure for pathologic diagnosis of gastric SETs. This procedure can help refine surgical indications and facilitate a proper treatment decisions for gastric SETs, especially in the cardia.