Imaging gastrointestinal stromal tumors

Gastric gastrointestinal stromal tumor (GIST) with co-occurrence of pancreatic neuroendocrine tumor

Mesenchymal tumors make up only about 1% of primary GI tumors, with Gastrointestinal Stromal Tumors (GIST) being the most common nonepithelial GI neoplasms. They are derived from the Interstitial cells of Cajal (ICC), and occur predominantly in older individuals, with a mean age of diagnosis of 64 years. Here we discuss the case of a 39-year-old female with atypical thoracic back pain wrapping around to the front and migrating diffuse abdomen pain that sometimes radiates into the chest. Upon imaging, a gastric GIST of the greater curve of the stomach was found incidentally on investigation of a pancreatic mass that was revealed to be a co-occurring pancreatic neuroendocrine tumor. For management of the gastric GIST and pancreatic neuroendocrine tumor, this patient underwent partial gastrectomy with gastrojejunostomy, partial pancreatectomy, splenectomy, and cholecystectomy with no complications.

Small Bowel Neoplasms: A Pictorial Review

Small bowel tumors are rare and account for approximately 3% of all gastrointestinal tumors in the United States. The incidence of small bowel neoplasms is rising-in particular, there is a rising incidence of small bowel carcinoid tumors. This may in part be due to small bowel lesion identification in an increasing number of cross-sectional imaging studies performed for other indications as well as increased use of advanced imaging techniques to assess specifically for small bowel disease. Diagnosis is a challenge owing to nonspecific clinical manifestation, rare occurrence, and low index of clinical suspicion. Yet, various small bowel neoplasms have characteristic imaging features at CT and MRI when optimal distention of the small bowel is achieved, correlating well with features seen in gross specimens. Understanding the imaging features of small bowel neoplasms is important to improve the radiologist's ability to diagnose and characterize small bowel neoplasms. Most small bowel tumors are clinically silent for long periods, and nearly half of the benign tumors are found incidentally during surgery or at cross-sectional imaging performed for other reasons. The authors review the imaging features of common benign and malignant small bowel neoplasms to aid the radiologist in diagnosis of small bowel tumors. ^©RSNA, 2020.

Small bowel gastrointestinal stromal tumor: a retrospective study of 32 cases at a single center and review of the literature

Background

Gastrointestinal stromal tumor (GIST) is a rare tumor of the small bowel, which can be difficult to diagnose and has a varied clinical outcome.

Purpose

This is a retrospective review of the diagnosis, management, and clinical outcome of 32 patients diagnosed with primary small bowel GIST from a single center and a comparison of the findings with previously published cases.

Patients and methods

Retrospective review of data from patient clinical records, endoscopic and imaging findings, surgical procedures, tumor histology and immunohistochemistry, and clinical outcome was conducted.

Results

Data of 32 patients with a median age of 56 years including 50% men and women were reviewed. The majority (29/32) were symptomatic at presentation, with the main symptom being gastrointestinal bleeding (15/32). Imaging detection rates included ultrasound (0%), magnetic resonance imaging (0%), computed tomography (54.8%), computed tomography angiography (71.4%), and double-balloon enteroscopy (88.9%). The mean tumor diameter was 5.3 cm; 4 tumors were located in the duodenum, 21 in the jejunum, and 7 in the ileum. Based on the tumor size and mitotic index, 5 (15.6%), 15 (46.9%), 0 (0%), and 12 (37.5%) patients were classified into very low-risk, low-risk, intermediate-risk, and high-risk groups. Immunohistochemistry showed positive expression for CD117 (100%), CD34 (81.2%), DOG1 (93.8%), smooth muscle actin (37.5%), S100 (9.4%), and desmin (6.2%). Twenty-five patients (78.1%) were treated with open surgical tumor resection; seven patients (21.9%) underwent laparoscopic surgery. Postoperative complications that occurred in seven patients (21.9%) were resolved with conservative management. Four patients were treated with postoperative imatinib. At median follow-up of 30 months, two patients were died.

Conclusion

The findings from this case series, combined with the findings from previously published cases, provide an update on the current status of the diagnosis and the therapeutic approaches that might lead to improvement in prognosis for patients who present with primary small bowel GIST.

Clinicopathological and molecular characteristics of synchronous gastric adenocarcinoma and gastrointestinal stromal tumors

Synchronous gastric tumors that consist of both gastrointestinal stromal tumor (GIST) and adenocarcinoma are rare. We studied the clinicopathological and molecular characteristics of six cases containing both gastric adenocarcinoma and GIST. By means of immunohistochemical analysis, all GIST cells expressed CD117, CD34 and Dog1 in all six synchronous gastric adenocarcinomas with GIST, and in GIST alone. Sequencing analysis demonstrated that exon 11 c-kit mutations were present in two of six synchronous tumors and four of five GISTs. One of the two exon 11 c-kit mutations in synchronous adenocarcinomas with GISTs was an uncommon mutation of CTT > CCA at amino acid 576, and the other was a GTT deletion at amino acid 560. The mutation was a homozygous A > G mutation in exon 12 (amino acid 567) of PDGFR-α. We concluded that the exon 11 mutations were the most important in both cases of synchronous gastric adenocarcinoma with GIST and GIST alone. The mutation rate was higher in GIST alone than in synchronous adenocarcinoma with GIST.

Gastrointestinal stromal tumour of the stomach in an 8-year-old boy

We report a case of an 8-year-old boy who underwent an ultrasound for investigation of a left upper quadrant mass and who was subsequently diagnosed with gastrointestinal stromal tumour of his stomach. Abdominal ultrasound showed a large cystic mass in the left upper abdomen which was further characterised by magnetic resonance imaging. At laparotomy, a large cystic lesion was excised from his stomach, which was confirmed at histology to be a gastrointestinal stromal tumour. We briefly discuss the presentation and imaging findings of paediatric gastrointestinal stromal tumour and how it differs from the adult form of the disease and treatments.

MRI of the stomach: a pictorial review with a focus on oncological applications and gastric motility

The purpose of this pictorial review is to demonstrate gastric pathology seen on magnetic resonance imaging (MRI) and discuss the essential MRI sequences for the evaluation of benign and malignant gastric pathologies. Common tumors of the stomach, polyposis syndromes, iatrogenic conditions, as well as other conditions of the stomach will be reviewed. The utility of MRI in the evaluation of patients with gastric malignancies and disorders of gastric motility will also be discussed.

Small Bowel Stromal Tumors: Different Clinicopathologic and Computed Tomography Features in Various Anatomic Sites

Gastrointestinal stromal tumors (GISTs) can present with different clinical and immunohistochemical characteristics according to different anatomic sites. The aim of this study was to compare clinicopathologic and computed tomography (CT) features of small bowel stromal tumors located in the duodenum, jejunum, and ileum. In total, 197 patients (109 male, 88 female) with small bowel GISTs were retrospectively reviewed. All tumors had definite anatomic sites in the small bowel tract with surgical confirmation. The clinicopathologic variables included age, sex, onset of symptoms, and tumor risk category. CT variables included tumor size, degree enhancement, enhancement pattern (region of necrosis), adjacent tissue involvement, lymphadenopathy, and distant metastasis. We assessed any possible differences according to different GIST site of origin. Based on tumor size and mitotic count, the risk categories in different anatomic sites did not differ significantly between duodenal and jejunal GISTs. However, high risk ileum GISTs accounted for 66.0% of ileal cases, which was higher than duodenum cases (36.8%, P = 0.002) and jejunum cases (43.9%, P = 0.004). The mean size of GISTs in the ileum was 9.77 cm, which was significantly larger than in the duodenum (7.41 cm, P = 0.043), and in the jejunum (8.14 cm, P = 0.027). On CT images, enhancement degree appeared to gradually increase from the duodenum to the ileum in the portal phase, and the enhancement pattern presented a tendency for heterogeneity. In Conclusions, the clinicopathologic and CT features of small bowel GISTs can differ according to different primary anatomic sites.

Contrast-enhanced endoscopic ultrasonography can predict a higher malignant potential of gastrointestinal stromal tumors by visualizing large newly formed vessels

BACKGROUND

The aim of this study was to elucidate the histologic and clinical implications of detection of intratumoral vessels on contrast-enhanced endoscopic ultrasonography (CE-EUS) in gastrointestinal stromal tumors (GISTs).

METHODS

Thirteen patients with a GIST, all of whom were referred for surgery, underwent presurgical CE-EUS. The malignant potential, assessed according to the modified Fletcher risk classification system, and the histologic degree of angiogenesis were compared with the presence or absence of intratumoral vessels on CE-EUS.

RESULTS

Of the six tumors with intratumoral vessels observed on CE-EUS, five were intermediate- or high-risk GISTs, and the remaining seven negative cases were categorized as very low risk or low risk. The presence of intratumoral vessels on CE-EUS was significantly correlated with a higher-risk classification (p = 0.005). On histologic examination, all GISTs having visualized vessels incorporated vessels of more than 500 μm in diameter. The large intratumoral vessels of the five intermediate- or high-risk GISTs lacked elastic fibers, suggesting that they were neovascular in nature. These higher-risk tumors were also found, by immunohistochemical analysis, to have high expression of vascular endothelial growth factor.

CONCLUSIONS

Intratumoral vessels observed in GISTs on CE-EUS are correlated with a higher degree of angiogenesis, resulting in higher malignant potential.

A Pancreatic Head Tumor Arising as a Duodenal GIST: A Case Report and Review of the Literature

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal tumors of the gastrointestinal tract that originate from the intestinal cells of Cajal (ICC) (Fletcher et al., 2002). Only a few cases have been described with extragastrointestinal stromal tumors (Kim et al., 2012; Soufi et al., 2013; Meng et al., 2011). They are often diagnosed as a pancreatic head tumor as they are very difficult to relate to the duodenum with CT, MRI, or ultrasound. We present a case of a sixty-four-year-old woman who presented with abdominal pain and cardialgia for a follow-up examination after breast cancer surgery. On laparotomy there was a 3 × 5 cm hypervascular mass arising from the pancreatic head with macroscopically no attachment to the duodenum. The patient underwent pancreatoduodenectomy (PD) modified after Traverso-Longmire, histopathology proved a duodenal GIST. This case proves that duodenal GISTs can grow invasively into the pancreas and appear as solid pancreas head tumor; therefore, these tumors should be included into differential diagnosis.

18F-fluorodeoxyglucose positron emission tomography/computed tomography findings of gastric lymphoma: Comparisons with gastric cancer

The role of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in numerous malignant tumors, including gastric lymphoma, is well-established. However, there have been few studies with regard to the ¹⁸F-FDG PET/CT features of gastric lymphoma. The aim of the present study was to characterize the ¹⁸F-FDG PET/CT features of gastric lymphoma, which were compared with those of gastric cancer. Prior to treatment, ¹⁸F-FDG PET/CT was performed on 24 patients with gastric lymphoma and 43 patients with gastric cancer. The ¹⁸F-FDG PET/CT pattern of gastric wall lesions was classified as one of three types: Type I, diffuse thickening of the gastric wall with increased FDG uptake infiltrating more than one-third of the total stomach; type II, segmental thickening of the gastric wall with elevated FDG uptake involving less than one-third of the total stomach; and type III, local thickening of the gastric wall with focal FDG uptake. The incidence of the involvement of more than one region of the stomach was higher in the patients with gastric lymphoma than in those with gastric cancer. Gastric FDG uptake was demonstrated in 23 of the 24 patients (95.8%) with gastric lymphoma and in 40 of the 43 patients (93.0%) with gastric cancer. Gastric lymphoma predominantly presented with type I and II lesions, whereas gastric cancer mainly presented with type II and III lesions. The maximal thickness was larger and the maximal standard uptake value (SUV_max) was higher in the patients with gastric lymphoma compared with those with gastric cancer. A positive correlation between the maximal thickness and SUV_max was confirmed for the gastric cancer lesions, but not for the gastric lymphoma lesions. There was no difference in the maximal thickness and SUV_max of the gastric wall lesions between the patients without and with extragastric involvement, for gastric lymphoma and gastric cancer. Overall, certain differences exist in the findings between gastric lymphoma and gastric cancer patients on ¹⁸F-FDG PET/CT images, which may contribute to the identification of gastric lymphoma.

Optimizing surgical and imatinib therapy for the treatment of gastrointestinal stromal tumors

INTRODUCTION

The discovery of activating KIT and PDGFRα mutations in gastrointestinal stromal tumors (GISTs) represented a milestone as it allowed clinicians to use tyrosine kinase inhibitors, like imatinib, to treat this sarcoma. Although surgery remains the only potentially curative treatment, patients who undergo complete resection may still experience local recurrence or distant metastases. Therapeutic strategies that combine surgical resection and adjuvant imatinib may represent the best treatment to maximize patient outcomes. In addition to the use of imatinib in the adjuvant and metastatic settings, neoadjuvant imatinib, employed as a cytoreductive therapy, can decrease tumor volume, increase the probability of complete resection, and may reduce surgery-related morbidities. Thus, selected patients with metastatic disease may be treated with a combination of preoperative imatinib and metastasectomy. However, it is critical that patients with GIST be evaluated by a multidisciplinary team to coordinate surgery and targeted therapy in order to maximize clinical outcomes.

DISCUSSION

Following a systematic literature review, we describe the presentation, diagnosis, and treatment of GIST, with a discussion of the risk assessment for imatinib therapy. The application of surgical options, combined with adjuvant/neoadjuvant or perioperative imatinib, and their potential impact on survival for patients with primary, recurrent, or metastatic GIST are discussed.

Gastrointestinal stromal tumors: the role of the gastroenterologist in diagnosis and risk stratification

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors that are best classified as sarcomas with variable aggressiveness. They are typically treated with surgical resection and adjuvant tyrosine kinase inhibitors or, for advanced/metastatic GISTs, with tyrosine kinase inhibitors alone. Gastroenterologists are often the first to detect GISTs and are, therefore, tasked with diagnosis and facilitation of early intervention. Diagnostic tools including various imaging techniques such as endoscopic ultrasound (EUS) and EUS-assisted tissue sampling are critical for an accurate diagnosis. In the case of small tumors, EUS-assisted resection or ligation techniques to treat asymptomatic small tumors have been described. This paper reviews current evidence for the diagnosis and management of GISTs, with an emphasis on the role of the gastroenterologist.

Multiple primary gastrointestinal stromal tumors presenting in jejunum and ileum

Multiple primary gastrointestinal stromal tumors (GIST) are an infrequent finding. Benign and malignant tumors could coexist in the same patient. We discuss one case of a benign jejunal GIST and a malignant ileal GIST coexisting in the same patient and present their radiological characteristics.

Imaging modalities of gastrointestinal stromal tumors

Recent dramatic improvement of survival of Gastrointestinal stromal tumor patients alongside the development of a new targeted treatment has made the role of imaging increasingly more important not only in diagnosing the disease, but also in monitoring the treatment effect and surveillance. Computed tomography is currently the imaging modality of choice for these purposes. This article reviews the current roles of different imaging modalities in clinical management of the gastrointestinal stromal tumors.

CT features, mimics and atypical presentations of gastrointestinal stromal tumor (GIST)

The term stromal tumor was coined in 1983 by Clark and Mazur for smooth muscle neoplasm of the gastrointestinal tract (GIT). Gastrointestinal stromal tumors (GIST) are nonepithelial tumors arising from the interstitial cells of Cajal, which express KIT protein-CD117 on immunohistochemistry. GIST can arise anywhere in the GIT, including the mesentery, omentum, and retroperitoneum.

Different sites and prognoses of gastrointestinal stromal tumors of the stomach: report of 187 cases

BACKGROUND

The stomach is the most common site of gastrointestinal stromal tumors (GISTs), but the clinical behavior of gastric GISTs at different sites is unclear. This study was designed to evaluate the clinicopathological (CP) parameters and influence of different gastric sites on outcome in patients with GIST.

METHODS

The CP and follow-up records of 187 patients with GIST who were treated at TianJin Medical University Cancer Institute & Hospital between January 1985 and December 2006 were reviewed. There were 97 men and 90 women (aged 17-88 (median, 56.5) years). CP factors were assessed for overall survival (OS) by using univariate and multivariate analysis.

RESULTS

The numbers of cases of upper, middle, and lower third gastric GISTs were 69 (36.9%), 103 (55.1%), and 15 (8%), respectively. Sites of GISTs in the middle or upper stomach, tumor size, intermediate- or high-risk groups, high mitotic count, and low resection status were associated with poor OS (p = 0.041, 0.046, 0.006, 0.000, 0.000, respectively) in a univariate analysis. In a multivariate analysis, tumor location in the upper and middle third of the stomach (p = 0.035), an intermediate or high risk (p = 0.01), and incomplete resection status (p = 0.006) were predictive of poor OS.

CONCLUSIONS

Patients in intermediate- and high-risk groups had an unfavorable outcome. A complete resection is the most important treatment for survival. The location of GIST in the lower third of the stomach may be a favorable factor, and the significance of different tumor sites for prognosis of gastric GISTs needs to be further clarified.

Estimation of malignant potential of GI stromal tumors by contrast-enhanced harmonic EUS (with videos)

BACKGROUND

Contrast-enhanced harmonic EUS (CEH-EUS) is a new sonographic technique that uses US contrast agents and depicts intratumoral vessels in real time.

OBJECTIVE

To evaluate whether assessment of tumor vascularity by CEH-EUS can predict the preoperative malignancy risk of GI stromal tumors (GISTs).

DESIGN

Prospective study to observe GIST vascularity.

SETTING

Kinki University School of Medicine.

PATIENTS

Between June 2007 and September 2009, 76 consecutive patients suspected of having subepithelial lesions underwent CEH-EUS.

INTERVENTION

CEH-EUS was performed by using a prototype echoendoscope in an extended pure harmonic detection mode.

MAIN OUTCOME MEASUREMENTS

Resected GIST specimens in 29 patients who underwent surgical resection were divided into high-grade (n=16) and low-grade (n=13) malignancy groups based on mitotic activity. The abilities of EUS-guided FNA and CEH-EUS to diagnose the malignant potential were compared. The sensitivities with which contrast-enhanced multidetector CT, power-Doppler EUS, and CEH-EUS detected intratumoral vessels in high-grade malignancy GISTs also were compared.

RESULTS

CEH-EUS identified irregular vessels and thereby predicted GIST malignancies with a sensitivity, specificity, and accuracy of 100%, 63%, and 83%, respectively. Diagnosis of high-grade malignancy GISTs by EUS-guided FNA had a sensitivity, specificity, and accuracy of 63%, 92%, and 81%, respectively. Contrast-enhanced multidetector CT, power-Doppler EUS, and CEH-EUS detected intratumoral vessels in high-grade malignancy GISTs with sensitivities of 31%, 63%, and 100%, respectively (P<.05).

LIMITATIONS

A single center was involved in this study.

CONCLUSIONS

CEH-EUS successfully visualized intratumoral vessels and may play an important role in predicting the malignancy risk of GISTs.

Surgical management of gastric gastrointestinal stromal tumor: a single center experience

BACKGROUND/AIM

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Surgery remains the mainstay of curative treatment. Our objective is to evaluate the outcome of surgical treatment of primary gastric GIST.

MATERIALS AND METHODS

Between January 1997 and April 2008, thirty seven consecutive patients underwent resection for GISTs (35 patients with primary gastric GISTs and two patients with intestinal GISTs who were excluded from the study). These patients underwent upper endoscopy ± biopsy, barium meal and abdominal CT scan. Patients' demographics and clinical presentations were analyzed. Perioperative parameters measured included operative times, estimated blood loss, intraoperative finding, surgical techniques, morbidity and length of hospitalization. Recurrence and survival were also analyzed.

RESULTS

Of the 35 patients with gastric GISTs included in the study, 63% were female. The median age was 59 ± 14 years (range, 23 to 75 years). The primary presenting symptoms were bleeding and dyspepsia; 43% of these tumors were located mainly in the body of the stomach. Tumor size was < 10 cm in 80% of the patients. The average tumor size was 6.3 ± 3.2 cm (range from 3 to 13 cm). Regarding the surgical management, 20 patients (57%) underwent gastric wedge resection, eight patients (23%) underwent partial gastrectomy and the remaining seven patients (20%) underwent total gastrectomy. Radical resections were found in 32 patients (91.5%) while palliative resections were found in three patients (8.5%). The resected lymph nodes were negative in 32 patients (91.5%). Recurrence was noted in three patients, with a median time to recurrence of 14.3 months (range, 7 to 28 months). The three- and five-years survival in patients who underwent wedge resection was 92% and 81%, respectively, where it was 95% and 87%, respectively, in patients who underwent gastrectomy (either partial or total). There were no major intraoperative complications or mortalities.

CONCLUSION

Complete surgical resection either through wedge resection or gastrectomy with negative margins remains the gold standard treatment in the management of patients with primary resectable gastric GISTs.

[Imaging procedures for gastrointestinal stromal tumors]

Morphological and functional imaging methods are used for staging of gastrointestinal stromal tumors (GIST) and to follow-up GIST patients undergoing therapy. Computed tomography is the most frequently used morphological imaging procedure and has been recommended as the imaging method of choice according to current GIST guidelines. However, positron emission tomography using [(18)F]-2-fluoro-2-deoxy-D-glucose (FDG-PET) as the radiotracer has shown to be advantageous over morphological imaging procedures when assessing therapy response at an early time point. While tumor size reduction in morphological imaging typically requires time to develop, a decrease in FDG uptake can be detected as early as 24 h following therapy initiation. To overcome the limitations of size-based therapy response assessment on morphological imaging procedures, new density-based therapy response criteria have been developed and implemented for GIST. This review addresses both indications and accuracy of morphological and functional imaging modalities for GIST.

Gastrointestinal stromal tumours: a clinico-radiologic review from a single centre in South India

Gastrointestinal stromal tumours (GISTs) are rare tumours but are the commonest mesenchymal neoplasms in the gastrointestinal tract. To our knowledge, there is no large case series in Asian countries in which a clinico-radiological descriptive analysis of these tumours has been carried out. In this retrospective study, we analysed our experience of 70 patients with histopathologically proven GISTs, who were presurgically investigated by using CT, and describe the demography, anatomical distribution, imaging features and clinical course of the GIST. We found an unusually large predominance of males in our study, stomach and small bowel appeared to have been involved similarly and small bowel tumours had a higher rate of metastases. We also highlight some unusual CT features of these tumours that we encountered during the study, such as the presence of metastatic lymphadenopathy and satellite nodules, relapse in appendices epiploicae of the bowel, metachronous liposarcoma, adrenal and lung metastases, multiplicity of lesions and aneurysmal dilatation of the bowel. Two of our patients also had multiple neurofibromas, whose association with GIST has been seen in earlier reports. To the best of our knowledge, this article presents one of the largest series of articles on GISTs, to date, in Asian countries. We conclude with a differential diagnosis of GIST, with salient features distinguishing each entity.

Surgical margin status and prognosis of gastrointestinal stromal tumor

BACKGROUND

Surgery is the best treatment for primary GIST and may be curative, but resection extension/completeness impact on the prognosis remains controversial. The authors aim was to evaluate the clinicopathological (CP) parameters and surgical margins status influence on GIST patients' outcome.

MATERIALS AND METHODS

The study evaluated 113 consecutive patients with sporadic GIST; the influence of CP parameters on recurrence-free survival (RFS) and disease-specific survival (DSS) was determined by univariate analysis (UA) and multivariate analysis (MA).

RESULTS

Of 104 cases, macroscopically complete resection was achieved in 96: R0 surgical margin status in 78 and R1 in 18. Recurrence rates (12.5%) were significantly lower in R0 (9.0%) than in R1 (27.8%). Tumor > 10 cm, mitotic count > 5/50 high power field (HPF), and high-risk GIST predicted poor RFS and DSS (UA). Disease-specific survival was significantly shorter after macroscopic incomplete (R2) resection, for mixed cellular morphology, and in tumors with necrosis (UA). High-risk GIST (p = 0.016) and R2 resection (p = 0.013) predicted poor DSS of patients (MA).

CONCLUSIONS

High risk and positive macroscopic surgical margin status are parameters associated with poor disease-specific survival in GIST patients.

Concomitant gastric adenocarcinoma and stromal tumor in a woman with polymyalgia rheumatica

Gastrointestinal stromal tumors (GISTs) are rare neoplasms (1%) of the gastrointestinal tract and to our knowledge only rare cases of synchronous presentation of gastric carcinomas and GISTs are reported in the literature. A 72-year-old female with a simultaneous presentation of gastric adenocarcinoma and GIST is presented. Moreover, due to polymyalgia rheumatica the patient received corticosteroids as treatment for the last 3 years. The concomitant occurrence of these neoplasms may involve common carcinogenic factors and there could be an association with polymyalgia rheumatica either as a paraneoplastic presentation or due to its treatment with corticosteroids.

A systematic review on the clinical diagnosis of gastrointestinal stromal tumors

BACKGROUND

The aim of this work was to assess the prevalence of symptoms of gastrointestinal stromal tumors (GISTs) and the diagnostic yield of clinical procedures for its diagnosis.

METHODS

Medical databases were consulted between 1998 and 2006 for potentially relevant publications. All studies dealing with the clinical presentation of GIST and related diagnostic procedures were included. Two researchers worked independently on the study selection, quality assessment, data extraction, and analysis phases of the study.

RESULTS

Forty-six observational studies were included with a total of 4,534 patients. Gastrointestinal bleeding was the most common clinical presentation. Twenty studies provided adequate information on the diagnostic yield of various procedures. The pooled diagnostic yield of endoscopy + mucosal biopsy and of intestinal contrast radiography was 33.8% (0-100%) and 35.1% (11-100%), respectively, while that of EUS and that of EUS-FNA was 68.7% (40-100%) and 84.0% (73.8-100%), respectively. Abdominal CT scan and MRI had similar pooled diagnostic yields: 73.6% (34.8-100%), and 91.7% (75-100%), respectively.

CONCLUSION

Endoscopy + mucosal biopsy should be reserved to patients with gastrointestinal bleeding. EUS-FNA provides direct visualization of the neoplasm and adequate samples for molecular diagnosis. EUS, abdominal CT and MRI may be considered valid alternatives whenever EUS-FNA is unavailable or a cytological diagnosis is unnecessary.

Gastrointestinal stromal tumours: CT findings

The aim of this study was to identify the predictors of malignancy and to demonstrate the uncommon radiological features of gastrointestinal stromal tumours (GIST) using CT. 30 patients participated in this retrospective study. CT findings were evaluated by two radiologists, and categorical variables were compared using chi(2) or Fisher's exact tests. These tests were used to assess any possible relationships between mitotic index and (i) tumour location, size, contour and growth status, (ii) presence of calcifications, necrosis or lymphadenopathy, (iii) enhancement pattern, (iv) metastasis to the liver or other distant sites and (v) invasion of the mesentery or adjacent organs. Tumours were located in the stomach (n = 22), small bowel (n = 6) and colon (n = 2). The size, localization, enhancement pattern, metastasis to the liver or other distant sites and the cystic-necrotic component of the tumours were all associated with a high mitotic index in statistical analyses (p<0.05). Uncommon radiological findings seen on CT were saccular aneurysmal dilatation, malignant lymphadenopathy and satellite nodules. In conclusion, CT features of GISTs were helpful in identifying predictors of malignant behaviour.

Gastrointestinal stromal tumor

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. These form a distinct category of tumors characterized by oncogenic mutations of the KIT receptor tyrosine kinase in a majority of patients. KIT is used not only for diagnosis but also for targeted therapy of GISTs. Imatinib, a tyrosine kinase inhibitor, is widely used in the treatment of advanced and metastatic GISTs and has been recently employed in the neo adjuvant and adjuvant set-up with encouraging results. Certain specific mutations in an exon (such as in exon 9) of the KIT gene result in GISTs that are relatively unresponsive to the Imatinib treatment. New therapeutic agents like Sunitinib have now been approved for the treatment of Imatinib-resistant GIST. This review summarizes the salient features of GIST along with a detailed review of targeted multi-disciplinary approach to the treatment of these special tumors.

A gastrointestinal stromal tumor with mesenteric and retroperitoneal invasion

Background

Gastrointestinal stromal tumors are rare visceral sarcomas arising in the gastrointestinal tract wall. In this report we present a case of gastrointestinal stromal tumors with mesenteric and retroperitoneal invasion, describe and discuss its computed tomography findings.

Case presentation

A 57-years-old male patient has been complaining of abdominal distention, weight lose, and hematuria. During physical examination, significant distention and multiple palpable tumor masses were identified on the abdomen. Abdominal computed tomography showed multiple, well-defined, soft tissue masses with homogenous and heterogeneous pattern, in the mesenteric and retroperitoneal areas. Unlike specific features of gastrointestinal stromal tumor, renal obstruction and atypical central calcification without chemotherapy that has not been yet described were seen in this case. Computed tomography did not reveal liver metastases and/or the lymph nodes with pathological size. Ultrasonography-guided true-cut^® biopsy was made, histopathologic and immunohistochemical analyses demonstrated stromal tumor which, C-KIT (+). The patient underwent left ureterectomy, left nephrectomy and total colectomy. Postoperative histopathological analyses revealed lower grade malignant GISTs. As of 17 months after the surgery, he is alive and free of recurrence.

Conclusion

When intraabdominal, multiple, large (>5 cm), well-circumscribed, homogenous or heterogeneous mass lesions without ascites, omental caking and lymph nodes metasteses were seen, gastrointestinal stromal tumors should be considered in the differential diagnosis.

Efficacy of preoperative combined 18-fluorodeoxyglucose positron emission tomography and computed tomography for assessing primary rectal cancer response to neoadjuvant therapy

PURPOSE

Efficacy of F-18 fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) for determining neoadjuvant therapy response in rectal cancer is not well established. We sought to evaluate serial FDG-PET/CT for assessing tumor down-staging, percentage residual tumor, and complete response or microscopic disease with rectal cancer neoadjuvant therapy.

METHODS

Patients with rectal cancer undergoing neoadjuvant therapy, definitive surgical resection, and FDG-PET/CT before and 4-6 weeks after neoadjuvant treatment were included. Tumors were evaluated pretreatment and on final pathology for size and stage. FDG-PET/CT parameters assessed were visual response score (VRS), standardized uptake value (SUV), PET-derived tumor volume (PETvol), CT-derived tumor volume (CTvol), and total lesion glycolysis (delta TLG).

RESULTS

Twenty-one rectal cancer patients over 3 years underwent neoadjuvant treatment, serial FDG-PET/CT, and resection. Complete response or microscopic disease (n = 7, 33%) was associated with higher Delta CTvol (AUC = 0.82, p = 0.004) and Delta SUV (AUC = 0.79, p = 0.01). Tumor down-staging (n = 14, 67%) was associated with greater Delta PETvol (AUC = 0.82, p < 0.001) and Delta SUV (AUC = 0.82, p < 0.001). Pathologic lymph node disease (n = 7, 33%) correlated with Delta CTvol (AUC = 0.75, p = 0.03) and Delta PETvol (AUC = 0.70, p = 0.08).

CONCLUSION

FDG-PET/CT parameters were best for assessing tumor down-staging and percentage of residual tumor after neoadjuvant treatment of rectal cancer and can potentially assist in treatment planning.

Gastric GIST: a single institutional retrospective experience with surgical treatment for primary disease

AIMS

Because gastric GISTs show variable clinical behavior, we reviewed our experience with primary gastric GISTs after surgical treatment and imatinib mesylate treatment for advanced disease.

METHODS

Between December 1995 and December 2005, 111 patients who underwent surgical treatment for primary gastric GISTs were enrolled in this study. Patients were grouped according to the risk assessment classification, and clinicopathological features, tumor recurrence and patient survival were assessed.

RESULTS

One patient was included in the very low risk group, 35 in the low risk group, 31 in the intermediate risk group and 44 in the high-risk group. All patients with very low, low and intermediate risk GISTs and 70% of patients with high risk GISTs underwent R0 resection. While there was no recurrence or metastasis in patients with very low, low and intermediate risk GISTs, 23% of those with high risk GISTs showed a distant metastasis at diagnosis and 35% of these patients had a recurrence after R0 resection. The overall 5-year survival rate of the high risk patients was 77.1%. Nineteen patients received imatinib mesylate therapy due to an incomplete resection or recurrence; 7 with no measurable lesion at the CT scan by a local tumor control showed no tumor progression after imatinib mesylate therapy, however, 12 patients with measurable lesions showed variable clinical courses after treatment. The overall 5-year survival rate of 19 patients with imatinib mesylate treatment was 80.0%.

CONCLUSIONS

The clinical outcome of the very low, low and intermediate risk gastric GISTs was excellent, while high risk gastric GISTs had a high rate of recurrence and therefore a less favorable outcome. A complete resection is the most important treatment for cure; however imatinib mesylate treatment may improve the clinical outcome of the patients with metastatic or recurrent gastric GISTs.

Gastrointestinal tract malignancies and positron emission tomography: an overview

(18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging is highly accurate in restaging colorectal cancer, esophageal cancer, and gastrointestinal stromal tumors. Overall, it compares favorably with anatomical imaging in the evaluation of tumor recurrence because metabolic abnormalities usually precede a structural change. Initial staging of these malignancies with PET is best used in patients with locally advanced disease who may benefit from curative resection if distant metastases are not found. It also appears to have great potential in predicting histopathologic response to neoadjuvant therapy and in monitoring the success of radiofrequency ablation and (90)Y microspheres radioembolization soon after intervention. FDG-PET can be used in other gastrointestinal malignancies as a prognostic tool and to detect distant disease but its role has not yet been well defined.

Case report: mesenteric schwannoma

Schwannomas are benign neurogenic tumors that arise from Schwann cells that line the sheaths of peripheral nerves. Schwannomas are commonly located in the soft tissues of the head and neck, extremities, mediastinum, retroperitoneum, and pelvis, but they are very rare in the mesentery. A 56-y-old man was admitted to the emergency service with nausea, vomiting, acute abdominal pain, and constipation. He reported weight loss and an intra-abdominal mass. On physical examination, the abdomen was distended, and a mass that was approximately 15 cm in diameter was palpated at the middle abdomen. Generalized abdominal tenderness and muscle spasm were noted. Air-fluid levels were seen on plain radiographs. Ultrasonography identified an intra-abdominal mass with intra-abdominal hemorrhage or perforation. Clinical signs and laboratory findings suggested an intra-abdominal mass, mechanical bowel obstruction, and an acute abdomen. The patient underwent surgery. The mass was completely excised and included a 4-cm-long intestinal segment that was densely adherent to the mass. Histopathologic and immunohistochemical examination revealed a mesenteric schwannoma. The patient was well 11 mo after surgery. Although schwannomas are very rare and generally asymptomatic, these tumors can become quite large and may cause acute abdominal problems such as mechanical bowel obstruction.

Ulcerated Gastrointestinal Stromal Tumor (GIST) with Ingested Bone Foreign Body Mimicking a Perforation with Abscess

Gastrointestinal stromal tumors (GIST) have a variety of appearances and can present as an intraluminal, extraluminal, solid or ulcerated mass. We present an unusual case of a patient presenting with pain, elevated white count, and computed topography (CT) findings suggesting an abscess containing bone. CT guided drainage was performed, and resulted in bowel perforation, leading to surgical intervention and the diagnosis of an ulcerated gastrointestinal stromal tumor containing bone.