Retrospective analysis of extra-gastrointestinal stromal tumors

Clinicopathological characteristics and long-term prognosis of peritoneal and retroperitoneal gastrointestinal stromal tumors

BACKGROUND

Peritoneal and retroperitoneal gastrointestinal stromal tumors (PRGISTs) are exceedingly uncommon, and their clinicopathological characteristics and long-term prognosis remain unreported. Therefore, our objective is to analyze these aspects of patients with PRGISTs using the Surveillance, Epidemiology, and End Results (SEER) database.

METHODS

Patients diagnosed with PRGISTs and small intestine stromal tumors (SISTs) between 2000 and 2019 were included in the study. Differences between groups were compared using Chi-square tests. Kaplan-Meier analysis and Cox proportional hazards models were used to evaluate overall survival (OS) and cancer-specific survival (CSS).

RESULTS

A total of 3817 patients were enrolled, with 3513 diagnosed with SISTs and 304 with PRGISTs. Compared to SISTs, PRGISTs patients were older, with larger tumors, higher mitotic rates, and greater risk of lymph node (5.3%) and distant (30.6%) metastasis (P < 0.001). Multivariate analysis identified N stage and mitotic rate as risk factors for distant metastasis in PRGISTs. In comparison to SISTs, PRGISTs patients exhibited a significantly worse OS (hazard ratio [HR] 1.83, 95% confidence interval [CI] 1.57-2.15, P < 0.001) and CSS (HR 2.11, 95% CI 1.73-2.58, P < 0.001). Subgroup analyses by age, sex, surgical status, chemotherapy, and marital status consistently demonstrated poorer OS and CSS for PRGISTs patients compared to SISTs patients (P < 0.05). The 1-, 3-, 5-, and 10-year OS rates for PRGISTs patients were 77.9%, 61.6%, 51.6%, and 32.8%, respectively, with corresponding CSS rates of 84.5%, 71.7%, 63.3%, and 49.0%. Multivariate Cox regression analysis identified age, race, surgical status, and mitotic rate as risk factors influencing OS, while race, surgical status, and mitotic rate were identified as risk factors affecting CSS.

CONCLUSIONS

In comparison to SISTs, PRGISTs patients exhibit distinct clinicopathological features and have a worse prognosis. However, surgical intervention can improve the prognosis of PRGISTs patients.

Establishment and validation of a prognostic nomogram for extra-gastrointestinal stromal tumors

Background

Extra-gastrointestinal stromal tumor (EGIST) is a rare subtype of gastrointestinal stromal tumor, with limited information on its clinical characteristics and prognostic factors. This study aims to identify the risk factors affecting survival in EGIST patients and to develop a prognostic nomogram for predicting EGIST-specific survival (TSS).

Methods

Patients diagnosed with EGIST, aged 18 to 80, were enrolled from the Surveillance, Epidemiology, and End Results (SEER) Research Plus database, covering the years 2000 to 2019. Univariate and multivariate analyses were conducted to identify risk factors for developing a nomogram. The predictive accuracy of the nomogram was evaluated using time-dependent receiver operating characteristic curves, calibration plots, and the concordance index. Decision curve analysis (DCA) was performed to assess the nomogram's clinical utility and net benefit for application in clinical practice. Additionally, the nomogram's performance was compared with the tumor SEER stage.

Results

A total of 389 patients were included in this study. Univariate and multivariate analyses identified age, household income, surgery, tumor grade, tumor size, and tumor SEER stage as significant predictors of TSS (all P<0.05). These factors were incorporated into the prognostic nomogram. The nomogram demonstrated superior prognostic value compared to the tumor SEER stage alone, as evidenced by the area under the curve and concordance index. The calibration plot indicated a high level of accuracy in forecasting survival probabilities. Furthermore, DCA highlighted the nomogram's clinical applicability and positive net benefit. The nomogram also proved more effective than the tumor SEER stage alone in identifying patients with poorer prognoses.

Conclusions

Age, household income, surgery, tumor grade, tumor size, and tumor SEER stage were identified as risk factors for TSS in patients with EGIST. We have developed and validated a prognostic nomogram to predict TSS in EGIST patients, which may improve patient management and guide personalized medical treatment for EGIST.

Extragastrointestinal Gastrointestinal Stromal Tumor Presenting as Paratesticular Mass - A Diagnostic Conundrum

Extragastrointestinal gastrointestinal stromal tumors are uncommon in the paratesticular region and pose a diagnostic challenge. A 47-year-old man presented with a painless testicular mass for three months. Ultrasonography showed a solid lesion in the right distal spermatic cord region. Excision of the mass showed an encapsulated solid, firm tumor of size 5 cm. Microscopic examination showed a spindle cell tumor arranged in fascicles, nodular and storiform patterns. The mitotic rate was 17-19/5 mm². The mesothelial lining of the tunica vaginalis was noted. Using immunohistochemistry, the tumor cells were positive for KIT, DOG1, and CD34, while negative for SMA, desmin, S100, STAT6, and EMA. H3K27me3 was retained in the tumor cells. The MIB-1 labeling index was 25% in the area of greatest labeling. We report an additional example of paratesticular EGIST and discuss the diagnostic approach and literature review. Knowledge about this tumor at rare sites and the clinicopathological features are needed for the definitive diagnosis and prognosis.

Case report: Clinical and molecular features of renal gastrointestinal tumor

While gastrointestinal stromal tumors (GISTs) often arise within the GI tract, it is well known that GISTs may also rarely emanate outside of the digestive system. Prior case reports have documented various primary sites in non-GI organs [extra-intestinal GIST (EGIST)], yet only one report has described a localized GIST of renal origin. Here, we describe a patient who presented with bilateral renal masses who was found to have a large unresectable renal GIST tumor treated with imatinib. We discuss treatment experience and response with systemic therapy and describe molecular data to contextualize this ultra-rare presentation within the landscape of EGIST tumors.

Trends and Financial Burden of Gastrointestinal Stromal Tumors in the United States: A Comprehensive Analysis of United States Hospitalizations

Background

Gastrointestinal stromal tumors (GISTs) are associated with a substantial economic burden to the healthcare system despite their relatively low incidence and prevalence compared to other more common malignancies. This study aimed to evaluate trends in GIST-related hospitalizations, inpatient mortality, and the financial burden of GISTs in the United States.

Methods

The National Inpatient Sample (NIS) database from 2016 to 2020 was used to identify adult hospitalizations (age > 18 years) with a primary diagnosis of GIST. A multivariate logistic regression along with Chi-square and t-tests was performed using SAS 9.4 software to analyze inpatient GIST-associated mortality, inflation-adjusted total hospital charge (THC), and length of stay (LOS) during the study period.

Results

The study analyzed 48,690 hospitalizations (49.2% female, mean age 64.2 years, 38.2% elective admissions) with a primary diagnosis of GIST between 2016 and 2020. Annual GIST-related hospitalizations increased from 2,645 in 2016 to 11,565 in 2020 (P = 0.1208). The most common tumor location was stomach (48.5%), followed by small intestine (18.7%), large intestine (3.6%), and rectum (1.6%). There was a non-significant reduction in inpatient mortality from 4.16% in 2016 to 3.29% in 2020 (P = 0.807). Overall, 36.2% of patients had THC between $10,000 and $20,000 (36.5% in 2016 vs. 34.7% in 2020, P = 0.0001), and 9.8% of patients had a THC > $40,000 (8.3% in 2016 vs. 12.6% in 2020, P = 0.0001). Furthermore, 61.5% of patients had LOS of fewer than 5 days (59.16% in 2016 vs. 61.39% by 2020, P = 0.0001), and 38.5% had LOS of 5 days or more (40.84% in 2016 vs. 38.61% in 2020, P = 0.0001). The proportion of GISTs treated with endoscopic resection has remained stable with 13.02% in 2016 and 13.01% in 2020 (P = 0.08). Additionally, the proportion of surgical excisions decreased from 26.8% in 2016 to 21.4% in 2020 with a statistically significant trend (P = 0.004).

Conclusions

GIST-related inpatient mortality between 2016 and 2020 has remained stable, and endoscopic and surgical interventions have become more common for the management of GISTs. This has been accompanied by a significant rise in overall inflation-adjusted hospitalization costs in the study period. These findings highlight the need for continued optimization of care and resource allocation for GIST management.

Laparoscopic-Assisted Resection for an Extra-gastrointestinal Stromal Tumor Arising From the Mesentery of the Small Intestine: A Case Report

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors that arise in the muscular or submucosal layers of the gastrointestinal tract. Extra-gastrointestinal stromal tumors (EGISTs) are rare primary entities that develop outside the digestive tract which are histologically and immunologically similar to GISTs. We present the case of a 52-year-old female diagnosed with a primary EGIST arising in the small bowel mesentery four months after undergoing hormone therapy for multiple uterine myomas. Transvaginal ultrasonography and MRI revealed a pelvic mass suspected to be a GIST. The patient was treated with laparoscopic-assisted partial resection of the small bowel. Histopathological examination of the surgical specimen confirmed the diagnosis of an EGIST. Imatinib treatment was initiated, and no clinical evidence of recurrence or metastasis was detected postoperatively. Because EGISTs are extremely rare, the differences between EGISTs and GISTs, the degree of malignancy, and prognosis have not been fully investigated. Further studies are needed to accumulate additional cases. The present case shows that laparoscopic-assisted excision can be successfully used to manage EGISTs.

Primary EGIST of the greater omentum - a rare presentation

Extragastrointestinal stromal tumors (EGISTs) are rare mesenchymal neoplasms, which develop in the retroperitoneum, mesentery, and omentum, lacking continuity to the stomach or intestines. Authors hereby present a female patient with a large heterogeneous abdominal mass as a case of an omental EGIST. A 46-year-old woman was referred to our hospital due to an insidious enlargement and colicky pain in the right iliac fossa. Abdominal palpation revealed a voluminous, freely mobile, and non-pulsatile mesoabdominal bulge expanding to the hypogastrium. On exploratory midline laparotomy, the tumor was densely fused to the greater omentum, not connected to the stomach, without gross involvement of adjacent structures. The large mass was completely excised after adequate mobilization. Immunohistochemical techniques showed strong and diffuse expression of WT1, actin and DOG-1, as well as multifocal c-KIT marking. Mutational study concluded a double mutation of KIT exon 9 and a mutation of PDGFRA exon 18. The patient was submitted to adjuvant treatment with imatinib mesylate 800 mg/day. Despite an extremely diverse presentation, omental EGISTs often remain clinically silent for a long time having enough space to grow before becoming symptomatic. These tumors have a consistent pattern of metastasis that typically spares lymph nodes unlike epithelial gut neoplasms. Surgery remains the preferred treatment for non-metastatic EGISTs of the greater omentum. It is possible that DOG-1 will supplant KIT as the leading marker in the future. The scarcity of knowledge on omental EGISTs implies a close monitoring of these patients to detect local relapse or distant metastasis.

Pancreatic Extragastrointestinal Stromal Tumor: A Case Report

Gastrointestinal stromal tumors (GISTs) are soft tissue sarcomas that originate from the mesenchymal cells of the gastrointestinal tract. Extra-GISTs (EGISTs) are caused by sites outside the gastrointestinal tract. We reported a case of EGIST of the pancreas in a 51-year-old woman. Enhanced CT scan showed a rounded, slightly hypointense focus in the head of the pancreas and the right pars compacta of the descending duodenum. Routine laboratory and endocrine tests were unremarkable. The patient underwent laparoscopic surgery. The diagnosis of EGIST was confirmed through histopathological and immunohistochemical examination. The tumor was found to be CD117+, CD34+, and DOG+ with a high risk of malignancy. No recurrence was observed during the nine-month postoperative follow-up.

Primary vulvar extragastrointestinal stromal tumor in a 77-year-old woman

Extragastrointestinal stromal tumors (EGISTs) carry the same morphological, immunohistochemical and molecular features as gastrointestinal stromal tumors (GISTs) and involve extragastrointestinal tract soft tissue. The majority of reported EGIST cases arise from intraabdominal, retroperitoneal, or pelvic soft tissue. A significant subset of such tumors originates from the gastrointestinal muscle layer, grows in an exophytic manner, then loses attachment to the gastrointestinal tract. Consequently, true EGISTs are exceedingly rare. Herein, we are reporting a case of a vulvar EGIST. A 77-year-old woman presented with a painless subcutaneous nodule on the right perineum. An excisional biopsy showed a fairly circumscribed bland spindle cell lesion in the dermis. The tumor cells were positive for CD117 and ANO1/DOG-1 and negative for smooth muscle myosin, smooth muscle actin, STAT6, low- and high-molecular-weight cytokeratins, SOX10, MART-1, CD10, S-100 protein, and estrogen and progesterone receptors. A diagnosis of EGIST was made and complete excision was recommended. Superficial/subcutaneous EGISTs are extremely rare, and it is important for dermatopathologists to be aware of this entity as it can be misdiagnosed as more common spindle cell neoplasms, both benign and malignant, including but not limited to smooth muscle neoplasms (leiomyoma/leiomyosarcoma), spindle cell melanoma, and sarcomatoid squamous cell carcinoma.

Extragastrointestinal stromal tumour of the transverse mesocolon mimicking giant ovarian cystic neoplasm

Gastrointestinal stromal tumours (GISTs) are mesenchymal tumours which are most commonly found along the gastrointestinal tract. They are more rarely found in an extragastrointestinal location and typically present late due to only vague symptoms from mass effect. There are very few case reports of GIST arising within the transverse mesocolon. We report a case of a large cystic transverse mesocolic GIST which preoperative imaging concluded was likely of ovarian origin. This resulted in an abrupt change in the surgical management intraoperatively, but fortunately, an R0 resection was still achieved. This serves as an important lesson to keep the differential diagnosis broad when dealing with large cystic abdominal masses. The tumour was found to be KIT wild type, with a platelet-derived growth factor receptor alpha D842V mutation identified, conferring intrinsic resistance to imatinib.

Multiple Metastatic Extra-gastrointestinal Stromal Tumors with Plasmoid Differentiation: A Case Report and Review of Literature

Extra-gastrointestinal stromal tumors (EGISTs) are rare mesenchymal tumors that arise from the abdominal, pelvic or retroperitoneal region, unrelated to the gastrointestinal tract. However, cases with a plasmoid morphology are extremely rare. we hererin report a 49-year-old man with abdominal pain who underwent magnetic resonance imaging that revealed an irregular tumor (103×71 mm) in size, in the space between stomach and pancreas, diagnosed as an EGISIT, we also reviewed the clinicopathological characteristics and immunohistochemical characteristics, molecular genetic features and differential diagnoses previously reported in the literature.

KIT (CD117) Positive Huge Primary Malignant Extra Gastrointestinal Stromal Tumors (EGISTs) Arising From Jejunal Mesentery: A Rare Case Report

Tumors arising outside gastrointestinal systems are known as extra gastrointestinal stromal tumors (EGISTs). Outside gastrointestinal sites include the mesentery, omentum, peritoneum, pancreas, and liver. Our case highlights a rare occurrence of an EGIST in jejunal mesentery in a 45-year-old male with an asymptomatic large abdominal growth and weight loss. A contrast-enhanced multi-dimensional computed tomography scan showed a large heterogeneous mass in the left hypochondrium. lumbar, and paraumbilical regions. Later, the patient underwent surgical resection of the tumor along with the involved jejunal segment and small tumor masses in the mesentery. Histopathological examination reported a malignant EGIST of mesentery and invasion into the jejunum, further confirmed by immunohistochemistry (IHC) markers like CD117 and smooth muscle actin with a high proliferative index (Ki67). One should be aware that these are different from other malignancies arising from the mesentery. Their cell of origin is different and needs a specific type of treatment. The clinical history, radiological findings, histopathology, and IHC help in diagnosing especially when they are arising from unusual areas like jejunal mesentery. Surgical intervention and chemotherapy are mainstay treatments.

Clinical Features of Extragastrointestinal Stromal Tumor Compared with Gastrointestinal Stromal Tumor: A Retrospective, Multicenter, Real-World Study

Objective

This study aimed to compare the tumor characteristics and long-term outcomes between EGIST and GIST. The confounding function was applied to improve the result credibility in the case of small sample size. Design, Setting, and Participants. This cohort study enrolled 55 patients with EGIST who underwent surgery and were selected from four high-volume hospitals in China and 221 GIST patients who were collected from one of the four hospitals between January 2006 and September 2017. We used propensity score matching (PSM) and subgroup analysis to compare EGIST with GIST in terms of prognosis. The confounding function was used for sensitivity analysis to reduce unmeasured confounding.

Results

We matched 43 patients in each of the GIST and EGIST groups by PSM. We compared EGIST data with GIST data to explore the prognostic factors between them. In the multivariate Cox regression model, tumor location of EGIST was negatively correlated with overall survival (after PSM: HR, 4.32; 95% CI, 1.22–15.26) or disease-free survival (after PSM: HR, 9.79; 95% CI, 2.22–43.31), which was also intuitively shown in the Kaplan–Meier survival curves (all P values < 0.05). In the subgroup analysis, EGIST with high risk factors had a worse prognosis than GIST. In unmeasured confounding analysis, the overall curve tends to show all combinations of c(0) of c(1) up to 2.0, none of which would bring the corrected relative risk to 1 for OS and DFS. Conclusions and Relevance. EGIST was associated with worse prognosis compared with GIST patients, particularly in EGIST patients with high risk factors, while there was a similar prognosis without those high risk factors.

Primary Extragastrointestinal Stromal Tumor of Greater Omentum with Intraperitoneal Bleeding

Gastrointestinal stromal tumors (GISTs) develop in the digestive tract, mainly in the stomach, small intestine, colon, or esophagus. However, primary tumors with the same pathologic features as GISTs have been reported to occur outside of the digestive tract and are called extragastrointestinal stromal tumor (EGIST). We herein report a rare case of EGIST arising from the greater omentum in a patient with abdominal pain caused by intraperitoneal bleeding from the tumor.

Curative intent treatment of late presented extragastrointestinal stromal tumor: two identical case reports with literature review

Gastrointestinal stromal tumors (GISTs) occurring outside the gastrointestinal tract are known as extragastrointestinal stromal tumors (EGIST). They share some common histopathologic and molecular characteristics. This report describes two female patients who were suspected of having a mesenteric GIST, but opted for surveillance rather than definitive treatment. Upon reassessment, both patients demonstrated increased tumor mass with no evidence of distant metastasis. The intraoperative findings confirmed the conclusion of clinical and imaging studies performed preoperatively and radical excisions were performed. Histopathological examination (spindle cell neoplasm) and immunohistochemistry (CD117) confirmed EGIST. Both patients underwent Imatinib therapy following surgery with no evidence of disease recurrence or metastasis upon follow up. Although sharing histologic features with GIST, EGIST frequently demonstrates distinct characteristics that facilitate the proper diagnosis and management of EGIST. Since it is a rare and aggressive disease with a poor outcome, early detection and curative surgical resection remains the mainstay of treatment.

Current knowledge of primary prostatic extra-gastrointestinal stromal tumor: a case report and review of the literature

The patient was a 62-year-old man diagnosed as having prostatic extra-gastrointestinal stromal tumor (EGIST) who was treated with imatinib. No recurrence or metastasis was found after a 6-month follow-up. We identified 14 cases of prostatic primary EGIST in PubMed and summarized these cases with our case. The patients' ages ranged from 31 to 78 years (average: 53.6 years), and most patients' prostate-specific antigen (PSA) concentrations were within normal limits (92.9%, 13/14). All patients underwent imaging examinations; prostatic masses measured 6 to 14.2 cm (mean: 9.43 cm), and imaging excluded secondary prostatic masses from the intestinal tract. By immunohistochemical staining, the tumors were positive for cluster of differentiation (CD)117 (71.4%, 10/14), DOG1 (100%, 7/7), and CD34 (100%, 14/14), and negative for smooth muscle actin (SMA) (71.4%, 10/14), desmin (100%, 11/11), and S100 (100%, 12/12). Treatment depended on the results of the gene mutation detection as well as the risk estimation according to tumor size and microscopic mitotic rates (>5 per 50 high-power fields: 60%, 6/10). Among the 12 patients with reported outcomes, nine achieved good results (no recurrence or metastasis), one achieved reduced mass volume, one experienced recurrence, and one died.

Primary retroperitoneal GIST: Case report and review of literature

Extraintestinal gastrointestinal stromal tumors (EGISTs) are mesenchymal tumor with no connection to tubular gastrointestinal system. They commonly arise from omentum and mesentry. Retroperitoneum is a rare primary site. We herein report a case of a 33 year old woman who underwent upfront surgery for primary retroperitoneal gastrointestinal stromal tumor and is now disease-free on adjuvant Imatinib.

Perianal extragastrointestinal stromal tumor

An extragastrointestinal stromal tumor (EGIST) is a gastrointestinal stromal tumor that arises outside of the gastrointestinal tract. Most EGISTs are located in the omentum, mesentery, and retroperitoneum. The occurrence of an EGIST at the perianal region is very rare. Herein, we report our experience with EGISTs in the perianal area and review the literature. A 70-year-old man presented to our hospital with a 2-year history of anal discomfort. A pelvic magnetic resonance imaging scan showed a homogenous, well-defined, soft tissue density mass. The patient underwent mass excision, and the pathological examination confirmed that the mass was an EGIST. The size of the tumor was 4.3×3.2 cm, and the mitotic count was 1 per 50 high-power fields. The tumor cells were immunohistochemically positive for KIT and CD34 but were negative for S-100 and alpha-smooth muscle actin. There were no other abnormal findings in the gastrointestinal tract; upon pathological review, this case was confirmed as perianal EGIST. Therefore, EGIST should be considered as a differential diagnosis of perianal masses.

Metachronous extragastrointestinal stromal tumor (EGIST) in utero: Report of an unusual case

INTRODUCTION

The gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor in the digestive tract. Currently, GIST is the name given to CD117 positive mesenchymal tumors, primary of the digestive tract, mesentery, and retroperitoneum. Nevertheless, they have been reported in the mesentery, omentum, gallbladder, bladder wall, and few cases in the uterus; known as extragastrointestinal stromal tumors (EGIST).

PRESENTATION OF CASE

Seventy-six-year-old woman with a history of the third recurrence of pelvic tumor located in the uterus initially diagnosed as uterine leiomyosarcoma. CT and MRI showed a tumor in the uterine corpus of approximately 10 cm. It was decided to perform the surgical rescue. The immunohistochemistry and anatomic pathology report revealed a tumor compatible with a uterine EGIST. It was decided to perform adjuvant treatment with imatinib. Currently, the patient continues to be disease-free 20 months after the surgery.

DISCUSSION

For years, GIST has often been confused with leiomyosarcoma, given that they are histologically almost indistinguishable. The IHC analysis for KIT (CD117) has become essential in the GIST diagnosis. On the other hand, stromal tumors arising outside the gastrointestinal tract are rare (5%), which have a histological and biological behavior similar to that of GISTs.

CONCLUSION

EGISTs are extremely rare and often incidentally detected. Currently, evidence about this location is scarce. According to the literature, this is the first case of uterine EGIST with a metachronous presentation.

Primary extra-gastrointestinal stromal tumor (EGIST) of the mesentery: Case report and review of literature

Introduction

Gastrointestinal stromal tumors (GISTs) represent <1% of all gastrointestinal (GI) tumors. Extra-gastrointestinal stromal tumors (EGISTs) are mesenchymal tissue neoplasm arising outside the GI tract. This rare group comprises only 5% of all GISTs. This case demonstrates a rare entity in a patient with non-specific symptoms, a large tumor size and unremarkable past personal and family history.

Presentation of case

We present a 45-year old man with non-specific symptoms who was diagnosed with a primary EGIST arising in the small bowel mesentery after surgery. The tumor was not compromising the GI tract and it was completely resected. The tumor was sent for pathological examination that confirmed the diagnosis. Histological examination revealed a 15 cm in diameter mass, comprised of spindle cells and high mitotic activity. Treatment with imatinib mesylate was initiated.

Discussion

There have been only a few previous reports of EGISTs arising from the small bowel mesentery. It is believed that EGISTs originate from cells with similar pathological characteristics and biological behaviour as the intestinal cells of Cajal. Such tumors are associated with poorer prognosis, lager tumor size and younger presentation than their GI counterparts. The preferred treatment is complete surgical resection. The addition of specific tyrosine kinase inhibitors such as imatinib mesylate is recommended for high risk patients. Even though morphological and immunohistochemical similarities between GISTs and EGISTs are described, their pathogenesis, incidence, genetic background, complications and prognosis are not completely known because they are extremely rare.

Conclusion

EGISTs are very rare tumors which originate from cells outside the GI tract and are associated with a more aggressive biological behavior than their GI counterparts. These tumors may grow without any clinical implications and should be kept in mind in the differential diagnosis for patients presenting with an abdominal mass. Further studies are needed due to lack of large patient cohort studies and long-term follow-up regarding the prognosis and management of this rare pathology.

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EGISTs are extremely rare. They represent only 5% of all GISTs, which comprises only <0.05% of all GI tumors.

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High index of suspicion in patients with nonspecific symptoms and the presence of an abdominal mass is necessary.

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The preferred treatment is a complete surgical resection in low-risk patients.

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Clinicopathologic parameters and clinical implications are not yet described in literature.

Imaging in gynecological disease (19): clinical and ultrasound features of extragastrointestinal stromal tumors (eGIST)

OBJECTIVE

To describe the clinical and sonographic characteristics of extragastrointestinal stromal tumors (eGISTs).

METHODS

This was a retrospective multicenter study. The data of patients with a histological diagnosis of eGIST who had undergone preoperative ultrasound examination were retrieved from the databases of nine large European gynecologic oncology centers. One investigator from each center reviewed stored images and ultrasound reports, and described the lesions using the terminology of the International Ovarian Tumor Analysis and Morphological Uterus Sonographic Assessment groups, following a predefined ultrasound evaluation form. Clinical, surgical and pathological information was also recorded.

RESULTS

Thirty-five women with an eGIST were identified; in 17 cases, the findings were incidental, and 18 cases were symptomatic. Median age was 57 years (range, 21-85 years). Tumor marker CA 125 was available in 23 (65.7%) patients, with a median level of 23 U/mL (range, 7-403 U/mL). The vast majority of eGISTs were intraperitoneal lesions (n = 32 (91.4%)); the remaining lesions were retroperitoneal (n = 2 (5.7%)) or preperitoneal (n = 1 (2.9%)). The most common site of the tumor was the abdomen (n = 23 (65.7%)), and less frequently the pelvis (n = 12 (34.3%)). eGISTs were typically large (median largest diameter, 79 mm) solid (n = 31 (88.6%)) tumors, and were less frequently multilocular-solid tumors (n = 4 (11.4%)). The echogenicity of solid tumors was uniform in 8/31 (25.8%) cases, which were all hypoechogenic. Twenty-three solid eGISTs were non-uniform, either with mixed echogenicity (9/23 (39.1%)) or with cystic areas (14/23 (60.9%)). The tumor shape was mainly lobular (n = 19 (54.3%)) or irregular (n = 10 (28.6%)). Tumors were typically richly vascularized (color score of 3 or 4, n = 31 (88.6%)) with no shadowing (n = 31 (88.6%)). Based on pattern recognition, eGISTs were usually correctly classified as a malignant lesion in the ultrasound reports (n = 32 (91.4%)), and the specific diagnosis of eGIST was the most frequent differential diagnosis (n = 16 (45.7%)), followed by primary ovarian cancer (n = 5 (14.3%)), lymphoma (n = 2 (5.7%)) and pedunculated uterine fibroid (n = 2 (5.7%)).

CONCLUSIONS

On ultrasound, eGISTs were usually solid, non-uniform pelvic or abdominal lobular tumors of mixed echogenicity, with or without cystic areas, with rich vascularization and no shadowing. The presence of a tumor with these features, without connection to the bowel wall, and not originating from the uterus or adnexa, is highly suspicious for eGIST. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Retroperitoneal Extragastrointestinal Stromal Tumors Have a Poor Survival Outcome: A Multicenter Observational Study

Purpose

Gastrointestinal stromal tumors (GISTs) are commonly known to be derived from the gastrointestinal (GI) tract, but recently there have been more and more literature describing lesions with similar pathological and immunohistochemical resembling GISTs but located outside the GI tract, and they have been termed as extra-GISTs (eGISTs). However, due to the rare incidence of eGISTs, its association with survival outcomes is poorly understood, especially in the Chinese population. Here, we aimed to identify the risk factors of eGISTs and to assess their association with overall survival (OS) and disease-free survival (DFS).

Patients and Methods

Data of pathologically confirmed eGISTs cases, without radiological and perioperative evidence of other primary lesions, and with no microscopically identified adhesion between the tumor and the gastrointestinal serosa, which were surgically treated between January 2006 and September 2017 were retrieved from the database of four high-volume hospitals. Immunohistochemical and genetic testing were performed on the postoperative lesions and were staged using the National Institutes of Health (NIH) criteria.

Results

A total of 55 cases were retrieved. eGISTs were identified from the retroperitoneum (36.4%), mesocolon (25.5%), small bowel mesentery (12.7%), abdominopelvic cavity (12.7%), lesser omental sac (5.5%), ovary (3.6%), pancreatic capsule (1.8%), or urinary bladder (1.8%). Based on the NIH risk classification, majority of the lesion were classified as high risk (85.5%). KIT 11 was the most common mutation site (76.5%) and 25.0% of the cases were wild-type eGISTs. Multivariate analyses showed that tumor location and size were independent factors affecting prognoses. Patients with tumors in the retroperitoneum had significantly poorer OS and DFS as compared to those in the non-retroperitoneum (HR [95% CI] for OS and DFS: 2.546 [1.023–6.337] [P = 0.037] and 2.475 [0.975–6.273] [P = 0.049], respectively). Similar findings were found for tumors of size >15 cm, compared to ≤15 cm (HR [95% CI] for OS and DFS: 5.350 [2.022–14.156] [P < 0.001] and 3.861 [1.493–9.988] [P = 0.003], respectively).

Conclusion

eGISTs were predominantly found from the retroperitoneum and mostly classified as high risk. Those located in the retroperitoneum and of size >15 cm had the poorer OS and DFS as compared to those in the non-retroperitoneum and of size <15 cm.

Prevalence, diagnosis, and treatment of primary hepatic gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GIST), which is the most common mesenchymal tumor of the digestive tract, account for 1%-3% of gastrointestinal tumors. Primary stromal tumors outside the gastrointestinal tract are collectively referred to as extra GISTs, and stromal tumors in different regions often have different prognoses. A primary hepatic GIST is a rare tumor with an unknown origin, which may be related to interstitial Cajal-like cells. Although primary hepatic GIST has certain characteristics on imaging, it lacks specific symptoms and signs; thus, the final diagnosis depends on pathological and genetic evidence. This review summarizes all cases of primary hepatic GIST described in the literature and comprehensively analyzes the detailed clinical data of all patients. In terms of treatment, local resection alone or with adjuvant therapy was the prioritized choice to obtain better disease-free survival and longer survival time. For advanced unresectable cases, imatinib mesylate was applied as the first-line chemotherapy agent. Moreover, transcatheter arterial chemoembolization, radiofrequency ablation, and microwave ablation were shown to improve overall survival for selected patients. Liver transplantation was a final treatment option after resistance to chemotherapy developed.

Retroperitoneal gastrointestinal stromal tumor: A case report and literature review

Retroperitoneal gastrointestinal tumor is the rarest subtype among 3 subtypes of extragastrointestinal tumors, which are uncommon stromal tumors. We herein report a case of a 55-year-old man with retroperitoneal gastrointestinal tumor detected by magnetic resonance imaging and confirmed by postoperative histology and immunohistochemistry.

Extra-gastrointestinal stromal tumor arising in the lesser omentum with a platelet-derived growth factor receptor alpha (PDGFRA) mutation: a case report and literature review

BACKGROUND

Gastrointestinal stromal tumors (GIST) arising from sites other than the gastrointestinal (GI) tract, termed extra-gastrointestinal stromal tumors (EGIST), are rare. Among EGIST, those with platelet-derived growth factor receptor alpha (PDGFRA) mutations are even rarer, with only a few cases reported. About 80% of GIST has KIT mutations, and 10% of GIST have PDGFRA mutations, which commonly affect the TK2 domain (exon 18). Among the exon 18 mutations, the D842V substitution is limited to gastric GIST. In EGIST, the degree of KIT and PDGFRA mutations varies on where the location of the tumor is, and it is suggested that omental EGIST is similar to gastric GIST. Adjuvant imatinib therapy is recommended for high-risk GIST; however, it is known that imatinib is less effective against GIST with a PDGFRA D842V mutation.

CASE PRESENTATION

A 75-year-old man was referred to our hospital with an extrinsic tumor of the lesser curvature of the gastric body. Intraoperative findings showed a tumor located outside of the lesser omentum with no connection between the tumor and the gastric wall. The tumor was subsequently resected. Pathological examination indicated a GIST arising in the lesser omentum measuring 70 mm in its longer dimension. Because the tumor had a PDGFRA mutation (D842V substitution), imatinib was suspected to lack efficacy to the tumor. Thus, although the tumor was considered clinically to have a high risk of recurrence, adjuvant imatinib therapy was not indicated. The patient has been free of recurrence for 29 months since the surgery.

CONCLUSION

We described a case of EGIST with a PDGFRA mutation arising in the lesser omentum. And we reviewed 57 cases of omental EGIST and showed that the clinicopathological characteristics and mutation status in omental EGIST were very similar to gastric GIST. In particular, PDGFAR D842V mutation rate in omental EGIST seemed as high as that in gastric GIST. These results suggested that omental EGIST is strongly related to gastric GIST, so the behavior of omental EGIST might be akin to gastric GIST. However, further studies are required to determine the prognosis and the necessity of adjuvant therapy for EGIST with a PDGFRA mutation.

Extragastrointestinal stromal tumour (EGIST) presented as a mesenteric and retroperitoneal mass

Extragastrointestinal stromal tumour (EGIST) occurs outside the gastrointestinal tract and has histopathological and molecular characteristics similar to gastrointestinal stromal tumour (GIST). This tumour is rare and aggressive. A male patient was admitted with anaemia and lower limb oedema. CT scan showed a tumour in the mesentery and retroperitoneum, suspected to be a small bowel GIST. During laparotomy an unresectable mass was found compressing the retroperitoneal structures. Pathology and immunohistochemistry (CD117) confirmed an EGIST. EGIST arises from Cajal-like cells or from pluripotent stem cells outside the gastrointestinal tract. It is aggressive and has a worse prognosis than GIST. Immunohistochemistry is crucial for diagnosis. Surgery aimed at debulking as much of a tumour mass as possible is the cornerstone of treatment. The role of imatinib is not clear. EGIST is rare and has a bad prognosis, and there is no consensus on grading and management. A low threshold of suspicion is crucial for early diagnosis.

Extragastrointestinal Stromal Tumor: A Differential Diagnosis of Compressive Upper Abdominal Tumor

Introduction

Extragastrointestinal stromal tumors (EGIST) are rare mesenchymal tumor lesions located outside the gastrointestinal tract. A rare compressing tumor with difficult diagnosis is reported.

Presentation of the Case

A male patient, 63 years old, was admitted in the emergency room complaining of stretching and continuous abdominal pain for one day. He took Hyoscine, with partial improvement of symptoms, but got worse due to hyporexia, and the abdominal pain persisted. The patient also reported early satiety and ten-pound weight loss over the last month.

Discussion

EGIST could be assessed by CT-guided biopsy, leading to diagnosis and proper treatment with surgical resection or Imatinib.

Conclusion

This case report highlights the importance of considering EGIST an important differential diagnosis of compressing upper abdominal tumors.

Extragastrointestinal Stromal Tumor (EGIST): A 16-Year Experience of 13 Cases Diagnosed at a Single Center

Background

Gastrointestinal stromal tumor (GISTs) rarely occurs outside the GI tract as extragastrointestinal stromal tumor (EGIST). The aim of this study was to review the clinical presentation, diagnosis, and outcome of EGIST at a single center.

Material/Methods

The study was a retrospective study performed at Istanbul University Hospital in a 16-year period and included patients with a histopathological diagnosis of EGIST confirmed to arise outside the GI tract. The patients’ available medical records included patient demographics, imaging and surgical data, and diagnostic histopathology reports. Cases of EGIST underwent follow-up for several years and the medical files of patients were well maintained.

Results

Thirteen cases of EGIST included six women and seven men, with a mean age of 59.6 years (range, 33–83 years). Eleven patients had EGISTs located in the intra-abdominal cavity, one patient’s tumor was in the retroperitoneum, and in the jejunal mesentery in one patient. The mean diameter of the EGISTs was 15.6 cm (range, 4–30 cm). Immunohistochemistry showed that all cases were negative for desmin, with positive immunostaining for CD34 (n=6), smooth muscle actin (SMA) (n=3), and Ki67 (n=6), without specific diagnostic markers. Following surgical resection, tumor recurrence occurred in three patients, and metastasis in two patients. The mean overall survival (OS) was 45.66 months (56.44 months for women; 32.57 months for men); the 5-year survival rate of our patients was 38%.

Conclusions

EGIST presented with a large tumor size at diagnosis, was mainly intra-abdominal, and had a low mean patient survival time with no specific diagnostic tissue immunomarkers.

Mucinous Carcinomatosis: A Rare Association between an Ovarian Tumor and an E-GIST

Pseudomyxoma peritonei (PMP) and extragastrointestinal stromal tumors (E-GISTs) are both rare entities. Most of the time, PMP is associated with an appendiceal tumor. An ovarian mucinous tumor can mimic appendiceal metastases. E-GIST is a mesenchymal tumor that can arise from the omentum, retroperitoneum, mesentery, or pleura. We present a case of an 87-year-old woman with mucinous carcinomatosis and acute intestinal occlusion submitted to an emergency laparotomy. She has found to have a borderline mucinous tumor of the ovary from the intestinal type with several lesions of pseudomyxoma peritonei and an E-GIST from the epiploons retrocavity (intermediated risk). In the literature, no relation was found between these two rare tumors. E-GIST was an incidental finding in the context of a mucinous carcinomatosis.

Malignant Retroperitoneal Extra-Gastrointestinal Stromal Tumor: A Unique Entity

Extra-gastrointestinal stromal tumors (EGISTs) are a recently described group of tumors. A handful of less than 70 cases have been reported in English literature, so far, to the best of our knowledge. Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the alimentary canal. EGISTs are a unique entity, which require distinction from GISTs because, even though, they exhibit similar histology and immunohistochemistry to GISTs, they occur outside the gastrointestinal tract, i.e. in omentum, mesentery, retroperitoneum, etc. and have different behavior patterns as far as their prognosis and management are concerned. Retroperitoneal sub-group of EGISTs is extremely rare and we report such a case of primary malignant EGIST of the retroperitoneum which presented as a soft tissue mass on radiological evaluation. The tumor turned out to be a histopathological surprise, and could be distinctively labeled as EGIST only after morphological and immunohistochemical studies. It is imperative for radiologists, pathologists and oncologists, among other clinicians, to be able to recognize and understand the presentation of this group of tumors due to their rapid progression and poor prognosis, so that an early diagnosis and management may be able to improve the final disease outcome.

Extra-Gastrointestinal Stromal Tumor of the Greater Omentum: Unusual Case Report

Gastrointestinal stromal tumors are the most common mesenchymal tumors of the gastrointestinal tract, originating from the interstitial cells of Cajal and most frequently expressing CD-117, a C-kit proto-oncogene, which can be detected immunohistochemically. Extra-gastrointestinal stromal tumors are neoplasms with similar immunohistological features arising outside the gastrointestinal tract with no connection to the gastric or intestinal wall.We report the case of a 61-year-old Moroccan man who presented with chronic abdominal pain along with progressive abdominal distension for the past last year. The clinical examination demonstrated a large abdominal mass and an abdominal computed tomography scan revealed a voluminous intraperitoneal mass measuring 30 cm in its greatest diameter. At laparotomy, this mass seemed to be arising from the greater omentum without continuity to the gastrointestinal tract. The mass was completely removed with clear margins and pathological examination was suggestive for high-risk gastrointestinal stromal tumor of the greater omentum. Due to the aggressive nature of this patient's tumor, he was assigned to receive imatinib as adjuvant chemotherapy for 3 years. He remains alive without any sign of recurrence after 4 years of follow-up.Extra-gastrointestinal stromal tumors of the greater omentum can grow slowly and remain clinically silent despite the large size of the tumor. Complete surgical resection is the only effective treatment approach. Nevertheless, adjuvant therapy following resection with imatinib has become a standard of care in cases of high risk disease.

Expression of L1 protein correlates with cluster of differentiation 24 and integrin β1 expression in gastrointestinal stromal tumors

The present study examined 66 cases of gastrointestinal stromal tumors (GISTs), 20 cases of smooth muscle tumors, 20 cases of schwannomas and 20 cases of normal gastric tissues in order to analyze the expression of L1, cluster of differentiation (CD)24 and integrin β1 by immunohistochemical staining. Patients were subjected to follow-up, and survival data were evaluated. L1 expression was detected in 57.6% of GIST cases; this was a significantly higher percentage compared with that found in the smooth muscle tumor cases or the normal control group. CD24 and integrin β1 were also expressed at significantly higher levels in the GIST cases than in the normal control group, although no significant difference was found in the expression levels of these proteins in smooth muscle tumor or schwannoma cases. These higher levels of L1 and integrin β1 expression were associated with an increased risk of invasive GIST, and were significantly positively correlated with Ki-67 expression. CD24 expression was not associated with the risk of GIST invasion or Ki-67 expression. There were positive correlations between L1, CD24 and integrin β1 expression; however, these had no significant association with patient survival. Therefore, L1 alone or in conjunction with CD24 (L1 + CD24), or integrin β1 (L1 + integrin β1) can be considered a valuable indicator for the differential diagnosis of GIST. Furthermore, L1 and integrin β1 can be used alone or in combination to evaluate the biological behavior of GISTs. Future studies are required to evaluate the prognostic value of these markers.