Pathophysiology, diagnosis, and treatment of gastrointestinal stromal tumors

Co-relation of gastrointestinal stromal tumors in a patient with leiomyoma cutis- A rare association

INTRODUCTION AND IMPORTANCE

Cutaneous leiomyomas, benign tumors from smooth muscle fibers, constitute about 5 % of all leiomyomas. They exhibit diverse inheritance patterns and can be linked to systemic malignancies. Gastrointestinal stromal tumors (GISTs), arising from the interstitial cells of Cajal, are the most common mesenchymal tumors in the gastrointestinal tract. Despite their prevalence, simultaneous occurrences of cutaneous leiomyomas and GISTs are rare, necessitating exploration of their potential relationship.

CASE PRESENTATION

A 25-year-old male with no significant medical history presented with multiple painful erythematous nodules on his chest, upper back, and arms. Histopathological analysis diagnosed these as multiple cutaneous piloleiomyomatosis. Despite recommendations for surgical intervention, the patient chose medical management and experienced significant pain relief with nifedipine. Later, the development of abdominal symptoms led to the discovery of multiple gastric lesions, diagnosed as benign spindle cell neoplasms, necessitating partial gastrectomy.

CLINICAL DISCUSSION

The differential diagnosis of cutaneous leiomyomas includes various soft tissue tumors, requiring histopathological confirmation. Genetic mutations affecting proteins critical to cellular energy production and tumor suppression underlie these conditions. Treatment options include pharmacological management and surgical excision. The discovery of GISTs in this patient aligns with rare literature reports, emphasizing the need for vigilant evaluation of systemic malignancies in patients with leiomyomatosis.

CONCLUSION

This case highlights the potential of cutaneous leiomyomas to indicate deeper malignancies like GISTs, stressing the importance of interdisciplinary collaboration in diagnosis and treatment. It underscores the interconnectedness of benign dermatological conditions and internal malignancies, advocating for comprehensive evaluation in patients with leiomyomatosis.

METHODS

This case report meticulously follows the SCARE 2023 guidelines: updating consensus Surgical Case Report guidelines (Sohrabi et al., 2023 [1]). These guidelines ensure high-quality reporting in surgical case reports. The report details the evaluation, diagnosis, and a comprehensive review of the literature pertaining to a patient with multiple leiomyoma cutis associated with gastrointestinal stromal tumors. By employing a multidisciplinary approach, this report achieves a thorough and standardized presentation of the case, serving as an additional tool for raising awareness regarding such rare conditions.

Surgery for multiple gastric gastrointestinal stromal tumors and large esophageal diverticulum related to germline mutation of the KIT gene: a case report

BACKGROUND

Familial gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the digestive tract caused by germline gain-of-function mutations in the KIT gene or platelet-derived growth factor receptor alpha gene (PDGFRA). These mutations cause not only multiple GISTs but also diffuse hyperplasia of interstitial cells of Cajal (ICCs), which is related to esophageal motility disorder.

CASE PRESENTATION

A 53-year-old man was referred to our hospital because of anemia and dysphagia. Fifteen years earlier, he had undergone a laparoscopic partial gastrectomy for multiple gastric GISTs with a germline mutation in exon 17 of the KIT gene. An upper gastrointestinal endoscopy revealed that the patient had multiple gastric GISTs and a large esophageal diverticulum directly above the esophagogastric junction. The largest gastric tumor was 7 cm, with a delle that might cause bleeding. Because the patient presented with dysphagia, we performed video-assisted thoracic esophagectomy and laparoscopic-assisted proximal gastrectomy simultaneously. The patient had survived without metastasis for 4 years after surgery and dysphagia had improved.

CONCLUSIONS

This is the first report of successful laparoscopic-thoracoscopic surgery for a patient with familial gastric GISTs accompanied with a large esophageal diverticulum.

Constipation and Postprandial Pain in a Patient With Shortness of Breath

Incidental image findings may be important for resolving seemingly unrelated symptoms at presentation.

Laparoscopic Partial Gastrectomy for Large Gastric GISTs

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are considered the most common mesenchymal tumors in the gastrointestinal tract and the stomach is the most frequently site affected (50-60%). The safety and feasibility of laparoscopic surgery for gastric GISTs of sizes larger than 5 cm remains unclear. It depends on the surgical skills, tumor location, and the learning curve of the surgeons.

METHODS

Between December 2013 and January 2021, 30 patients diagnosed with gastric GISTs underwent laparoscopic partial gastrectomy. This is a retrospective study done in Surgical Oncology unit, Oncology Center, Mansoura University, Egypt.

RESULTS

The most common tumor location was in the greater curvature in (46.7%). The mean tumor size was 9.5 cm (range 5-17 cm). All of the patients underwent laparoscopic partial gastrectomy. Associated splenectomy was done for only one patient. The mean operative time was 152.67 min and the estimated blood loss (EBL) was 139.33 ml. The mean hospital stay was 3.53 days. The mean follow-up period was 32.4 months.

CONCLUSION

Laparoscopic resection for gastric GISTs has become a feasible method. Patients with large tumors have the same favorable outcomes as small tumors. Large-sized GISTs may receive neoadjuvant therapy to downstage the disease and make it amenable for laparoscopic resection.

Targeted Deep Sequencing Reveals Unrecognized KIT Mutation Coexistent with NF1 Deficiency in GISTs

Purpose

NF1-deficient GISTs account for about 1% of gastrointestinal stromal tumors (GISTs) and are usually considered as a subtype of KIT/PDGFRA wild-type GISTs that have no detectable KIT and PDGFRA mutations. Some KIT/PDGFRA wild-type GISTs actually have cryptic KIT mutations (mKIT). So we investigate whether concurrent mKIT existed in NF1-associated GISTs.

Patients and Methods

Three independent cohorts were retrospectively analyzed. KIT/PDGFRA wild-type GISTs in Xiangya Hospital between May 2017 and Oct 2019 were investigated by next-generation sequencing (NGS) approach targeted 1021 cancer-related genes regions. GISTs cases in Gene+ dataset from May 2017 to May 2020 were collected from the platform of this company. The genotypes of GISTs in MSKCC cohort were downloaded from cBioPortal.

Results

A total of 290 cases including 23 KIT/PDGFRA wild-type GISTs in Xiangya Hospital, 136 GISTs in Gene+ database, and 131 GISTs in MSKCC were enrolled. Twenty-six cases have NF1 mutations (mNF1), and 48% (12/26) of NF1-mutated GISTs have concurrent mKIT. Compared with MSKCC (2/10, 20%), a higher ratio of mKIT in NF1-associated GISTs was detected in Xiangya Hospital (3/5, 60%) and Gene+ (7/11, 64%) (p<0.05). No mutation hotspot existed in mNF1. Most of mKIT centered within exon 11 (7/12, 58%) and others including exon 17 (3/12, 25%), exon 9(1/12, 8%), exon 13 (1/12, 8%) and exon 21 (1/12, 8%). No differences in age, gender, and location were detected between NF1-related GISTs with mKIT and those without mKIT. Three GIST cases of type I neurofibromatosis, skin neurofibromas and micro-GISTs (≤1 cm) were devoid of mKIT, but all the mini-GISTs (1~2 cm) and clinic GIST lesions (>2 cm) in two cases harbored mKIT.

Conclusion

mKIT was not unusual in NF1-associated GISTs, especially in Chinese populations. The gain-of-function mKIT possibly facilitated the progression of NF1-deficient lesions to clinic GISTs, however, the underlying mechanism warrants further studies.

Surgical treatment of gastrointestinal stromal tumours combined with imatinib treatment: a retrospective cohort analysis

BACKGROUND

Targeted therapies changed the treatment concepts of gastrointestinal stromal tumours significantly. As only possibility to cure surgical resection is the cornerstone of therapy. Thus it is necessary to find out which patients will benefit most regarding modality (neo- or adjuvant) and duration of chemotherapy.

METHODS

In a retrospective cohort analysis the medical records of all consecutive patients treated in the department of general and visceral surgery of the university hospital Tübingen between 2004 and 2015 were investigated. Recurrence and survival outcomes were calculated using the Kaplan-Meier method.

RESULTS

Tumor location of GIST was gastric in 32, small bowel in 14, rectum in 3 and extraintestinal in 3 patients. Median tumor size was 46 mm. Median mitotic index was 4 per 50 hpf. Resection was achieved R0 in 46 patients, R1 in 4 patients and R2 in 2 patients. Mean overall survival was 58.9 months (range, 46-73 months). Mean recurrence free survival was 45.6 months (range, 36-57 months). Mean overall survival was 58.9 months (range, 46-73 months). Risk factors for recurrence were tumor location and high mitotic index Ki-67.

CONCLUSIONS

The prognosis of GIST after surgical resection is favourable. Survival prognosis are excellent. Analysis of KI-67 mitotic index predicted best oncologic outcome.

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.

Association of Gastrointestinal Stromal Tumor and Acute Myeloid Leukemia Preceded by Myelodysplastic Syndrome with Refractory Anemia

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. GISTs are believed to be related to mutational activation of receptor tyrosine kinases, KIT, or platelet-derived growth factor receptor-alpha. The coexistence of GISTs with other neoplams has been extensively addressed in the literature. The most common second neoplasms are colorectal cancer, prostate cancer, and neoplasms derived from lymphoid tissue. In this case report, we describe a patient affected by GIST and acute myeloid leukemia preceded by myelodysplastic syndrome with refractory anemia. The clinicopathological characteristics of the patient are discussed and the literature is reviewed.

Orai1 mediates tumor-promoting store-operated Ca2+ entry in human gastrointestinal stromal tumors via c-KIT and the extracellular signal-regulated kinase pathway

Gastrointestinal stromal tumors originate from interstitial cells of Cajal, the pacemaker cells of the gut. Ca²⁺ regulates the pacemaker activity of interstitial cells of Cajal. Store-operated Ca²⁺ entry mediates the majority of Ca²⁺ entry in most cancer cells and may be a factor in regulating intracellular Ca²⁺ in interstitial cells of Cajal and gastrointestinal stromal tumors. Therefore, a blockade of this mechanism may affect the progression of gastrointestinal stromal tumors. Orai1 is the pore subunit of store-operated Ca²⁺ channels. Here, we reported that Orai1 was overexpressed in gastrointestinal stromal tumor tissues and was positively correlated with a high-risk grade in gastrointestinal stromal tumor patients. Furthermore, upon Orai1 silencing, the functional store-operated Ca²⁺ entry in gastrointestinal stromal tumor cells was decreased, indicating that the function of store-operated Ca²⁺ entry was mediated by Orai1. Inhibition of Orai1-mediated store-operated Ca²⁺ entry by Orai1 silencing or store-operated Ca²⁺ entry blockers (SKF-96365 and 2-aminoethyl diphenylborate) induced obvious cell proliferation suppression, cell-cycle distribution, and apoptosis stimulation in GIST-T1 cells. Conversely, Orai1 overexpression increased store-operated Ca²⁺ entry and cell proliferation in GIST882 cells. In addition, we found that activation of c-KIT and the extracellular signal-regulated kinase pathway participated in the oncogenic functions of Orai1-mediated store-operated Ca²⁺ entry in gastrointestinal stromal tumor cells. These results revealed that Orai1-mediated store-operated Ca²⁺ entry is critical for gastrointestinal stromal tumor cell proliferation via c-KIT and ERK signaling pathway activation. Orai1-mediated store-operated Ca²⁺ entry plays an oncogenic role and may be a novel prognostic factor and therapeutic target for patients with gastrointestinal stromal tumors.

Suppression of c-Kit signaling induces adult neurogenesis in the mouse intestine after myenteric plexus ablation with benzalkonium chloride

Adult neurogenesis rarely occurs in the enteric nervous system (ENS). In this study, we demonstrated that, after intestinal myenteric plexus (MP) ablation with benzalkonium chloride (BAC), adult neurogenesis in the ENS was significantly induced in c-kit loss-of-function mutant mice (W/W^v). Almost all neurons and fibers in the MP disappeared after BAC treatment. However, 1 week after ablation, substantial penetration of nerve fibers from the non-damaged area was observed in the MP, longitudinal muscle and subserosal layers in both wildtype and W/W^v mice. Two weeks after BAC treatment, in addition to the penetrating fibers, a substantial number of ectopic neurons appeared in the subserosal and longitudinal muscle layers of W/W^v mice, whereas only a few ectopic neurons appeared in wildtype mice. Such ectopic neurons expressed either excitatory or inhibitory intrinsic motor neuron markers and formed ganglion-like structures, including glial cells, synaptic vesicles and basal lamina. Furthermore, oral administration of imatinib, an inhibitor of c-Kit and an anticancer agent for gastrointestinal stromal tumors, markedly induced appearance of ectopic neurons after BAC treatment, even in wildtype mice. These results suggest that adult neurogenesis in the ENS is negatively regulated by c-Kit signaling in vivo.

Neurofibromatosis type 1 associated with pheochromocytoma and gastrointestinal stromal tumors: A case report and literature review

Neurofibromatosis type 1 (NF1) is a genetic disorder associated with neurofibromin 1 (NF1) gene mutation, which generates an increased risk of variety of tumor types. The current study reports a case involving NF1, pheochromocytoma (PHEO) and gastrointestinal stromal tumors (GIST). A 56-year-old man presented with abdominal pain and polypnea. Clinical investigation revealed multiple diffuse soft-tissue lesions throughout his body, and pigmented macules on the skin. Imaging analyses revealed thoracic scoliosis, multiple subcutaneous nodules in the abdomen and trunk, and a 7.0×7.7×8.9-cm oval-shaped, cystic mass in the left upper abdominal cavity. Immunohistochemical staining indicated that S-100 protein and synaptophysin were highly expressed in adrenal gland neoplasm, whilst CD117 and CD34 were highly expressed in small intestine tumors. The overall clinical and pathological finding suggested a diagnosis of NF1, giant PHEO and small intestinal stromal tumor. In addition, a literature review was conducted to identify the specific clinical features of patients with this condition. Only 11 similar cases have been reported worldwide. In the present study, paroxysmal hypertension occurred in the majority of patients, and GISTs tended to be located in the small intestine. In addition, the present study demonstrated that many of the patients had a poor prognosis. Therefore, the present study indicates that NF1-PHEO-GIST is a special type tumor with varied clinical symptoms, which may be associated with an increased risk for poor prognosis; however, more studies are required to confirm this.

Coexisting and possible primary extra-gastrointestinal stromal tumors of the pancreas and liver: A single case report

Gastrointestinal stromal tumors (GIST) are mesenchymal neoplasms of the gastrointestinal tract (GI) that are defined, in part, by the expression of CD117, a c-Kit proto-oncogene protein. GISTs emerge outside of the GI at a very low frequency, typically in a single organ or location. GISTs that occasionally emerge outside of the GI are classified as extra-gastrointestinal stromal tumors (EGIST). The present study reports an extremely rare case of EGIST detected in the pancreas and the liver. The pancreatic and liver tumors were 4.5×2.5 cm and 2.0×1.5 cm in size, respectively. Both tumors consisted of CD117-positive spindle cells with a similar mitotic rate of 1–2 per 50 high power fields. The pancreatic and the hepatic EGISTs were at a low risk of malignancy, and both tumors were proposed to be primary stromal tumors. To the best of our knowledge, this is the first report of likely primary EGIST identified in the pancreas and liver of the same patient.

Opinion: How to manage subepithelial lesions of the upper gastrointestinal tract?

Subepithelial lesions (SELs) in the upper gastrointestinal (GI) tract are relatively frequent findings in patients undergoing an upper GI endoscopy. These tumors, which are located below the epithelium and out of reach of conventional biopsy forceps, may pose a diagnostic challenge for the gastroenterologist, especially when SELs are indeterminate after endoscopy and endoscopic ultrasound (EUS). The decision to proceed with further investigation should take into consideration the size, location in the GI tract, and EUS features of SELs. Gastrointestinal stromal tumor (GIST) is an example of an SEL that has a well-recognized malignant potential. Unfortunately, EUS is not able to absolutely differentiate GISTs from other benign hypoechoic lesions from the fourth layer, such as leiomyomas. Therefore, EUS-guided fine needle aspiration (EUS-FNA) is an important tool for correct diagnosis of SELs. However, small lesions (size < 2 cm) have a poor diagnostic yield with EUS-FNA. Moreover, studies with EUS-core biopsy needles did not report higher rates of histologic and diagnostic yields when compared with EUS-FNA. The limited diagnostic yield of EUS-FNA and EUS-core biopsies of SELs has led to the development of more invasive endoscopic techniques for tissue acquisition. There are initial studies showing good results for tissue biopsy or resection of SELs with endoscopic submucosal dissection, suck-ligate-unroof-biopsy, and submucosal tunneling endoscopic resection.

The Hen or the Egg: Inflammatory Aspects of Murine MPN Models

It has been known for some time that solid tumors, especially gastrointestinal tumors, can arise on the basis of chronic inflammation. However, the role of inflammation in the genesis of hematological malignancies has not been extensively studied. Recent evidence clearly shows that changes in the bone marrow niche can suffice to induce myeloid diseases. Nonetheless, while it has been demonstrated that myeloproliferative neoplasms (MPN) are associated with a proinflammatory state, it is not clear whether inflammatory processes contribute to the induction or maintenance of MPN. More provocatively stated: which comes first, the hen or the egg, inflammation or MPN? In other words, can chronic inflammation itself trigger an MPN? In this review, we will describe the evidence supporting a role for inflammation in initiating and promoting MPN development. Furthermore, we will compare and contrast the data obtained in gastrointestinal tumors with observations in MPN patients and models, pointing out the opportunities provided by novel murine MPN models to address fundamental questions regarding the role of inflammatory stimuli in the molecular pathogenesis of MPN.

Gastrointestinal Stromal Tumour in a Patient with Multiple Cutaneous and Uterine Leiomyomatosis- Implications and Anaesthetic Management

Multiple cutaneous leiomyomatosis have been associated with uterine leiomyomatosis and known as Reed's syndrome or Multiple Cutaneous and Uterine Leiomyomatosis (MCUL). Gastrointestinal Stromal Tumours (GIST) have been reported to be associated with this syndrome only once previously in literature to the best of our knowledge. Here we report a rare case of GIST and multiple uterine leiomyomatosis in a middle aged patient with longstanding cutaneous leiomyomatosis who underwent GIST excision and hysterectomy. A 35 year old female patient with multiple cutaneous leiomyomatosis for the past 20 years was diagnosed to have gastrointestinal stromal tumour and multiple uterine leiomyomatosis for which she underwent laparotomy for GIST excision and hysterectomy. In the report we have elaborated the clinical and pathological observations as well as the anaesthetic management. This case report further substantiates the association of GIST with multiple cutaneous and uterine leiomyomatosis and also reminds us that cutaneous lesions can be clues to the diagnosis of underlying malignancy.

The functional role of long non-coding RNA in digestive system carcinomas

In recent years, long non-coding RNAs (lncRNAs) are emerging as either oncogenes or tumor suppressor genes. Recent evidences suggest that lncRNAs play a very important role in digestive system carcinomas. However, the biological function of lncRNAs in the vast majority of digestive system carcinomas remains unclear. Recently, increasing studies has begun to explore their molecular mechanisms and regulatory networks that they are implicated in tumorigenesis. In this review, we highlight the emerging functional role of lncRNAs in digestive system carcinomas. It is becoming clear that lncRNAs will be exciting and potentially useful for diagnosis and treatment of digestive system carcinomas, some of these lncRNAs might function as both diagnostic markers and the treatment targets of digestive system carcinomas.

Antitumor effect of the tyrosine kinase inhibitor nilotinib on gastrointestinal stromal tumor (GIST) and imatinib-resistant GIST cells

Despite the benefits of imatinib for treating gastrointestinal stromal tumors (GIST), the prognosis for high risk GIST and imatinib-resistant (IR) GIST remains poor. The mechanisms of imatinib resistance have not yet been fully clarified. The aim of the study was to establish imatinib-resistant cell lines and investigate nilotinib, a second generation tyrosine kinase inhibitor (TKI), in preclinical models of GIST and imatinib-resistant GIST. For a model of imatinib-resistant GIST, we generated resistant cells from GK1C and GK3C cell lines by exposing them to imatinib for 6 months. The parent cell lines GK1C and GK3C showed imatinib sensitivity with IC₅₀ of 4.59±0.97 µM and 11.15±1.48 µM, respectively. The imatinib-resistant cell lines GK1C-IR and GK3C-IR showed imatinib resistance with IC₅₀ values of 11.74±0.17 µM (P<0.001) and 41.37±1.07 µM (P<0.001), respectively. The phosphorylation status of key cell signaling pathways, receptor tyrosine kinase KIT (CD117), platelet-derived growth factor receptor alpha (PDGFRA) and downstream signaling kinases: serine-threonine kinase Akt (AKT) and extracellular signal-regulated kinase 1/2 (ERK1/2) or the non-receptor tyrosine kinase: proto-oncogene tyrosine-protein kinase Src (SRC), was analyzed in established cell lines and ERK1/2 phosphorylation was found to be increased compared to the parental cells. Nilotinib demonstrated significant antitumor efficacy against GIST xenograft lines and imatinib-resistant GIST cell lines. Thus, nilotinib may have clinical potential for patients with GIST or imatinib-resistant GIST.

CTHRC1 acts as a prognostic factor and promotes invasiveness of gastrointestinal stromal tumors by activating Wnt/PCP-Rho signaling

Gastrointestinal stromal tumors (GISTs) are the major gastrointestinal mesenchymal tumors with a variable malignancy ranging from a curable disorder to highly malignant sarcomas. Metastasis and recurrence are the main causes of death in GIST patients. To further explore the mechanism of metastasis and to more accurately estimate the recurrence risk of GISTs after surgery, the clinical significance and functional role of collagen triple helix repeat containing-1 (CTHRC1) in GIST were investigated. We found that CTHRC1 expression was gradually elevated as the risk grade of NIH classification increased, and was closely correlated with disease-free survival and overall survival in 412 GIST patients. In vitro experiments showed that recombinant CTHRC1 protein promoted the migration and invasion capacities of primary GIST cells. A luciferase reporter assay and pull down assay demonstrated that recombinant CTHRC1 protein activated noncanonical Wnt/PCP-Rho signaling but inhibited canonical Wnt signaling. The pro-motility effect of CTHRC1 on GIST cells was reversed by using a Wnt5a neutralizing antibody and inhibitors of Rac1 or ROCK. Taken together, these data indicate that CTHRC1 may serve as a new predictor of recurrence risk and prognosis in post-operative GIST patients and may play an important role in facilitating GIST progression. Furthermore, CTHRC1 promotes GIST cell migration and invasion by activating Wnt/PCP-Rho signaling, suggesting that the CTHRC1-Wnt/PCP-Rho axis may be a new therapeutic target for interventions against GIST invasion and metastasis.

Surgical management of gastrointestinal stromal tumors: a single center experience

INTRODUCTION

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal (GI) tract. Although the therapy targeted at inhibiting tyrosine kinases has shown dramatic results in metastatic and inoperable GISTs, the mainstay of treatment in primary localized forms remains surgical resection.

AIM

To provide an overview of our experience of GIST diagnosis and management, with emphasis on comparison of minimally invasive and open surgical resection for primary GISTs.

MATERIAL AND METHODS

We retrospectively reviewed the medical records of all patients who underwent surgical removal of GISTs from 2008 to 2012. Patient demographics, clinical data, surgery, complications, histopathological data and clinical course were analyzed.

RESULTS

Forty-four patients were identified. Average age at diagnosis was 63 years. Minimally invasive (MIS) and open surgery (OS) were each attempted in 22 (50.0%) patients. Laparoscopic removal was performed in 20, laparoendoscopic in 1, and laparoscopy-assisted endoscopic removal in 1. Conversion to an open procedure was performed in 4 (18.2%). We found significant differences in postoperative length of stay (8.5 days vs. 10.1 days, p < 0.001) and tumor size (2.93 cm vs. 5.78 cm, p = 0.018) between MIS and OS groups, respectively.

CONCLUSIONS

Laparoscopic removal is safe and effective for GISTs not exceeding 6 cm. Gastroesophageal junction and cardia GISTs require careful preoperative evaluation and planning to remove safely. We recommend avoiding laparoscopic removal of these tumors due to the high rate of conversion (100.0%) to an open procedure. Laparoendoscopic surgical approach is an appropriate technique for removal of small-sized intraluminal benign GISTs not involving the muscularis propria layer.

Contribution of DOG1 expression to the diagnosis of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract, and the majority contain KIT or PDGFRA-activating mutations. However, up to 10% of GISTs are c-kit-negative. Antibodies with increased sensitivity and specificity for the detection of c-kit-negative GIST cases may be of value, especially because some of these cases may also benefit from tyrosine kinase inhibitor therapy. Hematoxylin and Eosin sections of 33 GISTs were re-examined in order to define histopathological criteria used in risk assessment of these tumors. Immunohistochemistry with a panel of antibodies [c-kit, DOG1 (discovered on GIST 1), CD34, smooth muscle actin (SMA), Desmin, S100 and Ki67] was performed on 5μm-thick paraffin sections of all tumors. Statistical analysis of immunohistochemical studies showed that DOG1 and CD117 were the most sensitive and specific antibodies in the diagnosis of GISTs. Other antibodies were unhelpful in confirming a diagnosis of GIST, but were particularly useful in the differential diagnosis. Reactivity for DOG1 may aid in the diagnosis of GISTs, which fail to express c-kit antigen, and lead to appropriate treatment with imatinib mesylate, an inhibitor of the KIT tyrosine kinase.

Monitoring the effect of targeted therapies in a gastrointestinal stromal tumor xenograft using a clinical PET/CT

Purpose

The purpose of this study is to assess treatment responses induced by the two tyrosine kinase inhibitors, Imatinib and Sunitinib, in a gastrointestinal stromal tumor (GIST) xenograft using a clinical positron emission tomography/computed tomography (PET/CT) scanner.

Methods

Nude mice bearing human GIST xenografts with mutations in exons 11 and 17 were randomly allocated to treatment with Imatinib, Sunitinib, or placebo daily for seven consecutive days. 2-deoxy-2-[¹⁸F]fluoro-d-glucose PET (¹⁸F-FDG-PET/CT) was performed in a clinical PET/CT scanner at baseline (day 0) and 1 and 7 days after onset of treatment. Treatment response was assessed by measuring tumor volumes and by calculation of tumor-to-liver ¹⁸F-FDG uptake ratios.

Results

Minor reductions in tumor volume were observed in both treatment groups. For the two treatment groups, significantly decreased tumor-to-liver uptake ratios were observed both at day 1 (Imatinib, −41%, p = .002; Sunitinib, −55%, p < .001) and at day 8 (Imatinib, −35%, p < .001; Sunitinib, −50%, p < .001), when compared to individual baseline values. For the control tumors, neither tumor volumes nor tumor-to-liver uptake ratios were altered during the 8 days the experiment lasted.

Conclusions

Significant anti-tumor effects were demonstrated following treatment with both Imatinib and Sunitinib. Decreased tumor-to-liver uptake ratios were more pronounced than tumor volume reductions. Effects of novel targeted therapies can be evaluated in the GIST xenograft model using a clinical PET/CT scanner.

High-Risk CD117-Positive Gastrointestinal Stromal Tumor of the Colon in a 12-Year-Old Girl: Adjuvant Treatment with Imatinib Mesylate

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the alimentary tract rarely observed in children. The treatment of choice for GIST is surgical resection. Although the prognosis of GISTs with low malignant potential is excellent, high-malignant-potential GISTs have a high rate of recurrence. Prognostic factors such as tumor size, mitotic rate and presence of metastases may provide an indication for adjuvant imatinib mesylate (IM) treatment. Here we present a young patient with a large GIST with high-risk features who is in complete remission after surgical excision and adjuvant IM treatment. This patient is the only colon-located CD117-positive case where IM was administered. The exact indications as well as the optimal dose and duration of IM need to be clarified with the contribution of new cases and the growing experience of this rare disease.

Upregulation of miR-196a and HOTAIR drive malignant character in gastrointestinal stromal tumors

Large intergenic noncoding RNAs (lincRNA) have been less studied than miRNAs in cancer, although both offer considerable theranostic potential. In this study, we identified frequent upregulation of miR-196a and lincRNA HOTAIR in high-risk gastrointestinal stromal tumors (GIST). Overexpression of miR-196a was associated with high-risk grade, metastasis and poor survival among GIST specimens. miR-196a genes are located within the HOX gene clusters and microarray expression analysis revealed that the HOXC and HOTAIR gene were also coordinately upregulated in GISTs which overexpress miR-196a. In like manner, overexpression of HOTAIR was also strongly associated with high-risk grade and metastasis among GIST specimens. RNA interference-mediated knockdown of HOTAIR altered the expression of reported HOTAIR target genes and suppressed GIST cell invasiveness. These findings reveal concurrent overexpression of HOX genes with noncoding RNAs in human cancer in this setting, revealing miR-196a and HOTAIR as potentially useful biomarkers and therapeutic targets in malignant GISTs.

Metastatic gastrointestinal stromal tumor to the thoracic and lumbar spine: first reported case and surgical treatment

BACKGROUND CONTEXT

Metastatic epidural spinal cord compression from gastrointestinal stromal tumors (GISTs) is a rarely reported phenomenon.

PURPOSE

To describe the surgical management of metastatic GIST to two noncontiguous regions of the spinal column.

STUDY DESIGN

Case report.

METHODS

Review of the medical chart, radiographic studies, and relevant literature.

RESULTS

The patient underwent direct surgical decompression and stabilization of the cervicothoracic junction and the lumbar region during treatment of two distinct sites of metastatic pathology.

CONCLUSIONS

Treatment of epidural compression from metastatic GIST with direct decompression and stabilization is safe and feasible.

Microvessel Density (Chalkley Method) in a Series of 79 Gastrointestinal Stromal Tumors

BACKGROUND

Evaluation of the MVD (modified Chalkley method) in a series of 79 cases of GISTs diagnosed by the Pathology Service at the HCPA (Hospital de Clinicas de Porto Alegre) from January 1993 to December 2009.

METHODS

Seventy nine cases of GISTs were submitted to immunohistochemical analysis for CD31, an endothelial marker, to analyze MVD. Hot spots were identified for each case, and the mean numbers of stained blood vessels collected through Chalkley count, with the use of a 25 point grid, placed onto a scanned image. Images were analysed through an image analysis system. We used a cutoff of six vessels.

RESULTS

Our series was composed of 42 males and 37 females and presented an average age of 58.9 years. GISTs were predominately located in the stomach (45.6%) followed by the small intestine (38.0%). Sixty seven GISTs (84.8%) showed an average of less than six vessels stained by CD31 (MVD) and 12 (15.2%) GISTs an average of more than six vessels. A statistically significant difference was observed between survival rate of patients having GISTs with MVD of ≤ 6 vessels (mean = 2.4, CI 95%: 1.67 - 3.17) and patients having GISTs with MVD of ≥ 6 vessels (mean = 2.4, CI 95%: 1.67 - 3.17), P = 0.001. No association for MVD was observed related to sex, age, histological type, risk category, location and metastasis.

CONCLUSIONS

Seventy nine cases of GISTs diagnosed at a single center in South Brazil were studied for MVD (Chalkley method). There was a statistically significant difference between MVD and the survival rate for these patients. The use of Chalkley method in GISTs may be helpful to evaluate clinical outcome.

A multidisciplinary survey on controversies in the use of EUS-guided FNA: assessing perspectives of surgeons, oncologists and gastroenterologists

BACKGROUND

EUS-guided FNA can help diagnose and differentiate between various pancreatic and other lesions.The aim of this study was to compare approaches among involved/relevant physicians to the controversies surrounding the use of FNA in EUS.

METHODS

A five-case survey was developed, piloted, and validated. It was collected from a total of 101 physicians, who were all either gastroenterologists (GIs), surgeons or oncologists. The survey compared the management strategies chosen by members of these relevant disciplines regarding EUS-guided FNA.

RESULTS

For CT operable T2NOM0 pancreatic tumors the research demonstrated variance as to whether to undertake EUS-guided FNA, at p < 0.05. For inoperable pancreatic tumors 66.7% of oncologists, 62.2% of surgeons and 79.1% of GIs opted for FNA (p < 0.05). For cystic pancreatic lesions, oncologists were more likely to send patients to surgery without FNA. For stable simple pancreatic cysts (23 mm), most physicians (66.67%) did not recommend FNA. For a submucosal gastric 19 mm lesion, 63.2% of surgeons recommended FNA, vs. 90.0% of oncologists (p < 0.05).

CONCLUSIONS

Controversies as to ideal application of EUS-FNA persist. Optimal guidelines should reflect the needs and concerns of the multidisciplinary team who treat patients who need EUS-FNA. Multi-specialty meetings assembled to manage patients with these disorders may be enlightening and may help develop consensus.

Assessing the Activity of Cediranib, a VEGFR-2/3 Tyrosine Kinase Inhibitor, against VEGFR-1 and Members of the Structurally Related PDGFR Family

Cediranib is a potent inhibitor of the VEGF receptor (VEGFR)-2 and VEGFR-3 tyrosine kinases. This study assessed the activity of cediranib against the VEGFR-1 tyrosine kinase and the platelet-derived growth factor receptor (PDGFR)-associated kinases c-Kit, PDGFR-α, and PDGFR-β. Cediranib inhibited VEGF-A–stimulated VEGFR-1 activation in AG1-G1-Flt1 cells (IC50 = 1.2 nmol/L). VEGF-A induced greatest phosphorylation of VEGFR-1 at tyrosine residues Y1048 and Y1053; this was reversed by cediranib. Potency against VEGFR-1 was comparable with that previously observed versus VEGFR-2 and VEGFR-3. Cediranib also showed significant activity against wild-type c-Kit in cellular phosphorylation assays (IC50 = 1–3 nmol/L) and in a stem cell factor–induced proliferation assay (IC50 = 13 nmol/L). Furthermore, phosphorylation of wild-type c-Kit in NCI-H526 tumor xenografts was reduced markedly following oral administration of cediranib (≥1.5 mg/kg/d) to tumor-bearing nude mice. The activity of cediranib against PDGFR-β and PDGFR-α was studied in tumor cell lines, vascular smooth muscle cells (VSMC), and a fibroblast line using PDGF-AA and PDGF-BB ligands. Both receptor phosphorylation (IC50 = 12–32 nmol/L) and PDGF-BB–stimulated cellular proliferation (IC50 = 32 nmol/L in human VSMCs; 64 nmol/L in osteosarcoma cells) were inhibited. In vivo, ligand-induced PDGFR-β phosphorylation in murine lung tissue was inhibited by 55% following treatment with cediranib at 6 mg/kg but not at 3 mg/kg or less. In contrast, in C6 rat glial tumor xenografts in mice, ligand-induced phosphorylation of both PDGFR-α and PDGFR-β was reduced by 46% to 61% with 0.75 mg/kg cediranib. Additional selectivity was showed versus Flt-3, CSF-1R, EGFR, FGFR1, and FGFR4. Collectively, these data indicate that cediranib is a potent pan-VEGFR kinase inhibitor with similar activity against c-Kit but is significantly less potent than PDGFR-α and PDGFR-β. Mol Cancer Ther; 10(5); 861–73. ©2011 AACR.

A decade of tyrosine kinase inhibitor therapy: Historical and current perspectives on targeted therapy for GIST

The introduction of molecularly targeted therapies has ushered in a considerable transformation in the management of gastrointestinal stromal tumors (GIST) that currently defines the paradigm of targeted therapy for solid tumors. Indeed, in the past decade the management of GIST has evolved from a disease only effectively treatable by surgery to the archetype of a tumor treatable with a molecularly targeted therapy. Better understanding of the molecular and genetic characteristics that underlie the aberrant behavior of GIST has increased the accuracy of its diagnosis and allowed for the identification of distinct genetic hallmarks, prognostic groups, and treatment strategies. Collectively, this has resulted in the development of the targeted tyrosine kinase inhibitors (TKIs) imatinib and sunitinib, and continues to prompt studies of novel agents in this disease. Since approval in 2002, imatinib has been shown to provide a high level of clinical efficacy in patients with advanced GIST, including a median progression-free survival (PFS) of 2 years and median overall survival approaching 5 years, with some patients progression-free after 10 years of treatment. Imatinib is now also approved in adult patients following resection of KIT-positive GIST. In 2006, sunitinib was approved for the treatment of advanced GIST after failure of imatinib. Sunitinib provides significant benefit in this setting, with a median PFS close to 6 months after imatinib failure. Following progression on these agents, patients have limited treatment options. This critical unmet need is being addressed by the development of new TKIs and the use of novel regimens with approved agents.

Expression and mutational status of c-kit in thymic epithelial tumors

BACKGROUND

Overexpression of c-kit, a tyrosine kinase receptor protein encoded by the protooncogene kit, has been previously reported in thymic epithelial tumors and in other neoplasms such as gastrointestinal stromal tumors, myeloproliferative disorders, melanoma, and seminoma. Mutations in the kit gene have been related to response to imatinib in gastrointestinal stromal tumor and one case report of thymic carcinoma. We studied expression of c-kit in a large retrospective series of thymic epithelial malignancies and sequenced the whole gene in a subset of patients.

METHODS

Thymic epithelial tumors from 120 patients (13 thymic carcinomas and 107 thymomas) were examined. Immunohistochemical staining with an antic-kit polyclonal antibody was performed on a tissue microarray. Mutation analyses of exons 1 to 20 were conducted by direct DNA sequencing of polymerase chain reaction products in eight thymic carcinomas, five thymomas, and one thymic carcinoma cell line.

RESULTS

The percentage of c-kit positive cells was significantly higher in thymic carcinoma (46%) than in thymoma (4%). Decreased disease-related survival and progression-free survival were observed in c-kit positive tumors. No mutations were detected.

CONCLUSION

c-kit expression is strongly but not exclusively related to thymic carcinoma histotype, and it is of prognostic value. Mutations are very rare.

Inhibition of KIT RNAi mediated with adenovirus in gastrointestinal stromal tumor xenograft

AIM: To investigate a therapeutic method for gastrointestinal stromal tumor (GIST) based on KIT RNA interference (RNAi) with AdMax adenovirus.

METHODS: KIT short hairpin RNA (shRNA), whose lateral sides were decorated with restriction endonuclease sequences, was designed. T₄ DNA ligase catalyzed the joint of the KIT shRNA and the green fluorescent protein-containing PDC316-EGFP-U6 to form PDC316-EGFP-U6-KIT. Homologous recombination of AdEGFP-U6-KIT was performed with the AdMax system. Heterotopically transplanted GISTs were established in nude mice. AdEGFP-U6-KIT was intratumorally injected. The volume, inhibition ratio of tumor and CD117 expression of GIST graft tumor in nude mice were compared between test and control groups.

RESULTS: The length of KIT shRNA was determined to be about 50bp by agarose electrophoresis. Gene sequencing detected the designed KIT RNAi sequence in PDC316-EGFP-U6-KIT. After transfection with AdEGFP-U6-KIT, 293 cells displayed green fluorescence. The physical and infective titers of AdEGFP-U6-KIT were 5 × 10¹¹ viral particles/mL and 5.67 × 10⁷ plaque forming units/mL, respectively. The mean volume of the grafted tumor was significantly smaller in test mice than in control mice (75.3 ± 22.9 mm³vs 988.6 ± 30.5 mm³, t = -18.132, P < 0.05). The inhibition ratio of the tumors was 59.6% in the test group. CD117 positive expression was evident in two cases (20%) in the test group and 10 cases (100%) in the control group (χ² = 10.2083, P < 0.005).

CONCLUSION: AdEGFP-U6-KIT is successfully constructed, and KIT RNAi mediated with Admax vector system can effectively inhibit the expression of the KIT gene and the growth of GIST in nude mice.

A novel correlation between LINE-1 hypomethylation and the malignancy of gastrointestinal stromal tumors

PURPOSE

Gastrointestinal stromal tumors (GIST) are the most important mesenchymal tumors of the gastrointestinal tract. The vast majority of GISTs exhibit activating mutations of KIT or PDGFRA, but epigenetic alteration of GISTs is largely unknown. In this study, we aimed to clarify the involvement of DNA methylation in GIST malignancy.

EXPERIMENTAL DESIGN

A total of 106 GIST specimens were studied. Levels of LINE-1 methylation were analyzed using bisulfite pyrosequencing. In addition, methylation of three other repetitive sequences (Alu Yb8, Satellite-α, and NBL2) was similarly analyzed, and CpG island hypermethylation was analyzed using MethyLight. Array-based comparative genomic hybridization (array CGH) was carried out in 25 GIST specimens.

RESULTS

LINE-1 hypomethylation was significantly correlated with risk, and high-risk GISTs exhibited significantly lower levels of LINE-1 methylation than low-risk (61.3% versus 53.2%; P = 0.001) or intermediate-risk GISTs (60.8% versus 53.2%; P = 0.002). Hypomethylation of Satellite-α and NBL2 was also observed in high-risk GISTs. By contrast, promoter hypermethylation was relatively infrequent (CDH1, 11.2%; MLH1, 9.8%; SFRP1, 1.2%; SFRP2, 11.0%; CHFR, 9.8%; APC, 6.1%; CDKN2A, 0%; RASSF1A, 0%; RASSF2, 0%) and did not correlate with LINE-1 methylation or risk. Array CGH analysis revealed a significant correlation between LINE-1 hypomethylation and chromosomal aberrations.

CONCLUSIONS

Our data suggest that LINE-1 hypomethylation correlates significantly with the aggressiveness of GISTs and that LINE-1 methylation could be a useful marker for risk assessment. Hypomethylation may increase the malignant potential of GISTs by inducing accumulation of chromosomal aberrations.

NCCN Task Force report: update on the management of patients with gastrointestinal stromal tumors

The standard of care for managing patients with gastrointestinal stromal tumors (GISTs) rapidly changed after the introduction of effective molecularly targeted therapies involving tyrosine kinase inhibitors (TKIs), such as imatinib mesylate and sunitinib malate. A better understanding of the molecular characteristics of GISTs have improved the diagnostic accuracy and led to the discovery of novel immunomarkers and new mechanisms of resistance to TKI therapy, which in turn have resulted in the development of novel treatment strategies. To address these issues, the NCCN organized a task force consisting of a multidisciplinary panel of experts in the fields of medical oncology, surgical oncology, molecular diagnostics, and pathology to discuss the recent advances, identify areas of future research, and recommend an optimal approach to care for patients with GIST at all stages of disease. The task force met for the first time in October 2003 and again in December 2006 and October 2009. This supplement describes the recent developments in the field of GIST as discussed at the October 2009 meeting.

Sonographic findings in a patient with neurofibromatosis type 1 and a gastrointestinal stromal tumor

Gastrointestinal stromal tumors (GIST) have been suggested to be the most common neurofibromatosis 1-associated gastrointestinal tumors. This case report describes and compares US and CT findings of both abdominal neurofibromas and a gastrointestinal stromal tumor. On US, the GIST appeared as a well-defined inhomogeneous lesion with a target-like pattern similar to CT. The neurofibromas appeared as well-demarcated round nodules with a relatively homogeneous hypoechoic internal structure and were accompanied by subtle posterior acoustic enhancement. US and CT were able to differentiate between neurofibromatomas and GIST in this neurofibromatosis 1 patient; however, a biopsy of the suspicious mass was performed to clarify the diagnosis.

Expression of P16 and PDGFR-beta in gastric adenocarcinoma

OBJECTIVES

To detect immunohistochemistry expression of p16 and PDGFR-beta on gastric adenocarcinoma.

METHODS

Thirty six patients submitted to surgery for gastric adenocarcinoma between 1998 and 2002 at Santa Casa de Porto Alegre Hospital have been studied. Variables investigated were: age, gender, tumour size and localization, number of dissected and metastatic nodes, histological type, surgical resection extension and pathological staging.

RESULTS

No expression of PDGFR-beta has been detected on surgical specimens. Concerning to p16, loss of expression lower than 10% and 1% has been detected respectively on 89% and 79% of the specimens studied.

CONCLUSION

There has been no correlation among p16 loss and variables studied.

New progress in CT and MRI examination and diagnosis of small intestinal tumors

Precise examination and diagnosis of small intestinal tumors is difficult because of the curved course and overlapping canal of the small intestine. Traditional technology for intestinal canal examination and endoscopy cannot exhibit the intestinal wall and extra-luminal structure well. With the development and advancement of multi-slice spiral computed tomography and magnetic resonance imaging (MRI), computed tomography enteroclysis (CTE) and magnetic resonance enteroclysis (MRE) are widely used in the examination and diagnosis of small intestinal tumors. CTE and MRE, with three-dimensional imaging capabilities and excellent soft-tissue contrast, can analyze the abnormalities of peripheral intestinal structure as well as the tunica mucosa. In addition, these two technologies can clearly reveal the localization, appearance, degree of mesenteric infiltration and remote tumor metastasis, which increases our cognition of the imaging diagnosis for intestinal tumors. Here we review recent progress in imaging (CT and MRI) examination and diagnosis of small intestinal tumors.

NCCN Task Force report: update on the management of patients with gastrointestinal stromal tumors

The standard of care for managing patients with gastrointestinal stromal tumors (GISTs) rapidly changed after the introduction of effective molecularly targeted therapies involving tyrosine kinase inhibitors (TKIs), such as imatinib mesylate and sunitinib malate. A better understanding of the molecular characteristics of GISTs have improved the diagnostic accuracy and led to the discovery of novel immunomarkers and new mechanisms of resistance to TKI therapy, which in turn have resulted in the development of novel treatment strategies. To address these issues, the NCCN organized a task force consisting of a multidisciplinary panel of experts in the fields of medical oncology, surgical oncology, molecular diagnostics, and pathology to discuss the recent advances, identify areas of future research, and recommend an optimal approach to care for patients with GIST at all stages of disease. The task force met for the first time in October 2003 and again in December 2006 and October 2009. This supplement describes the recent developments in the field of GIST as discussed at the October 2009 meeting.

Gastric oncology: an update

PURPOSE OF REVIEW

As the field of endoscopy progresses, new tools and techniques continue to be developed for gastroenterology in general and gastrointestinal oncology in particular. Some of these include enhancements in diagnostic optics such as chromoendoscopy, magnification endoscopy, and confocal laser endomicroscopy. Others include advanced therapeutics such as endoscopic mucosal resection and endoscopic submucosal dissection. In this review, we will update the reader on these latest of technologies, their benefits and risks, as well as their role in evaluating, staging, and treating gastric neoplasms, especially gastric adenocarcinoma, gastrointestinal stromal tumors, and primary gastric lymphoma.

RECENT FINDINGS

Noteworthy studies in this review indicate that in properly selected patients with gastric adenocarcinoma, endoscopic submucosal dissection is a viable alternative to gastric resection with 100% 5-year survival rates; in patients with metastatic gastrointestinal stromal tumors, imatinib can provide effective treatment with reasonable outcome; and in patients with low grade mucosa-associated lymphoid tissue lymphoma, eradication therapy with antibiotics is curative with a very low recurrence rate.

SUMMARY

The advances discussed in this review have significantly improved the care we can offer our patients in gastric oncology. With continued advancement in the field, it will be crucial to continue to study outcomes and safety of these techniques and to develop structured training for those looking to perform these procedures.

Simultaneous adenocarcinoma and leiomyoma of the stomach presenting as a collision tumor

A 68-year old Japanese man was referred to the Cancer Institute Hospital for the treatment of a rectal cancer. Preoperative esophagogastroduodenoscopy revealed a submucosal tumor with ulcer formation near the esophagogastric junction of the stomach. The initial treatment strategy was to perform a proximal gastrectomy with limited lymph node dissection as well as a simultaneous anterior resection. However, histopathological examination of a biopsy specimen of the submucosal tumor revealed a moderately differentiated adenocarcinoma, and therefore a total gastrectomy with D2 lymph node dissection was performed. Histopathological examination of the resected specimen revealed both adenocarcinoma and leiomyoma presenting as a collision tumor. Preoperative accurate histopathological diagnosis of a gastric submucosal tumor is generally difficult. Consequently, surgical resection of large gastric submucosal tumors may be indicated in the absence of histopathological confirmation of the diagnosis. However, in this case preoperative histopathological diagnosis enabled surgeons to perform the appropriate surgery. We conclude that to determine the appropriate treatment strategy, preoperative histopathological examination of tumors should be performed even in a case of suspected submucosal tumor, particularly if mucosal ulceration is present.

Gastrointestinal stromal tumors and shock

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumor of the gastrointestinal tract. Clinically, they are associated with nonspecific symptoms, but some patients can present gastrointestinal bleeding with shock. We report two cases of GIST of the small bowel, revelated by hemorrhagic shock secondary to acute bleeding, succesfully treated by emergency surgery.

[Gastrointestinal stroma tumours (GIST) and the gastroenterologist]

Gastrointestinal stromal tumours are frequently incidental findings at gastrointestinal endoscopy. The most common location is the stomach. Larger tumours may cause abdominal pain or obscure or overt bleeding. Diagnosis and distinction from other submucosal tumours is usually done by the means of endoscopic ultrasound with fine needle aspiration. Lesions with a diameter of more than 3 cm at endosonography are associated with a high malignant potential. Today, endoscopic resection of gastrointestinal stromal tumours is not (yet) routinely performed.

Advanced gastrointestinal stromal tumor in Europe: a review of updated treatment recommendations

The European Society for Medical Oncology (ESMO) recommendations on the management of gastrointestinal stromal tumor (GIST) have recently been updated. Imatinib 400 mg/day remains the standard first-line treatment for patients with metastatic GIST. Mutational analysis has received a strong recommendation for diagnostic purposes. Furthermore, patients with KIT exon 9-activating mutations are now recommended to receive imatinib 800 mg/day as first-line treatment. Following progression during treatment with imatinib 400 mg/day, increasing the imatinib dose to 800 mg/day is advised. In the case of further progression or intolerance to imatinib, sunitinib 50 mg/day (schedule 4/2) is recommended. This article reviews the evidence underlying the updates to the ESMO recommendations on the management of GIST and discusses the implications of the changes.

EUS-guided FNA for the diagnosis of GI stromal cell tumors: sensitivity and cytologic yield

BACKGROUND

EUS-guided FNA has been well documented to aid in the diagnosis of subepithelial lesions by providing cytologic material. Studies to date evaluating the sensitivity of EUS-FNA for the diagnosis of GI stromal cell tumors (GIST) have been small, and few have relied on surgical histologic diagnosis as the reference standard.

OBJECTIVE

Our purpose was to determine the diagnostic yield and sensitivity of EUS-FNA for the diagnosis of GIST and to identify EUS features of GIST that are predictive of the ability to obtain adequate tissue by EUS-FNA.

DESIGN

All patients with histologically confirmed, c-kit-positive GIST who underwent EUS-FNA from 1998 to 2006 were reviewed. EUS images were examined for mass size, shape, location, wall layer, heterogeneity, echogenicity, cystic spaces, lobulation, ulceration, and central umbilication. Needle gauge, number of needle passes, and presence of a cytologist during the EUS-FNA were recorded.

RESULTS

A total of 37 patients (29 with diagnostic FNA cytology; 8 with nondiagnostic cytology) met the inclusion criteria. The diagnostic yield and sensitivity of EUS-FNA cytology for the diagnosis of GIST was 78.4% (29/37). The sensitivity was 84.4% (27/32) for GISTs located in the stomach, but poor for lesions located in the duodenum because none of these tumors yielded diagnostic cytology (n = 3). An increase in size up to 10 cm, round/oval shape, and identification of the origin of GIST within a specific sonographic wall layer were statistically significant in their ability to predict adequate tissue yield.

CONCLUSIONS

The sensitivity of EUS-FNA cytology for the diagnosis of GIST is 78.4% and is influenced by size, location, shape, and layer of origin.

Perioperative and oncological outcome of laparoscopic resection of gastrointestinal stromal tumour (GIST) of the stomach

Background. Surgery remains the only curative treatment for gastrointestinal stromal tumour (GIST). Resection needs to ensure tumour-free margins while lymphadenectomy is not required. Thus, partial gastric resection is the treatment of choice for small gastric GISTs. Evidence on whether performing resection laparoscopically compromises outcome is limited. Methods. We compiled patients undergoing laparoscopic resection of suspected gastric GIST between 2003 and 2007. Follow-up was performed to obtain information on tumour recurrence. Results. Laparoscopic resection with free margins was performed in 21/22 patients. Histology confirmed GIST in 17 cases, 4 tumours were benign neoplasms. Median operation time and postoperative stay for GIST patients were 130 (range 80-201) mins and 7 (range 5-95) days. Two patients experienced stapler line leakage necessitating surgical revision. After median follow-up of 18 (range 1-53) months, no recurrence occurred. Conclusions. Laparoscopic resection of gastric GISTs yields good perioperative outcomes. Oncologic outcome needs to be assessed with longer follow-up. For posterior lesions, special precaution is needed. Laparoscopic resection could become standard for circumscribed gastric GISTs if necessary precautions for oncological procedures are observed.

Laparoscopic resection of sporadic synchronous gastric and jejunal gastrointestinal stromal tumors: report of a case

Multicentricity of gastrointestinal stromal tumors (GISTs) has been described only in patients with neurofibromatosis type 1 (NF1) or within the small intestine, and different pathogenetic mechanisms are involved. We report a case of synchronous sporadic gastric and jejunal GISTs, which were resected laparoscopically in a 67-year-old man. Immunohistochemical analysis revealed that both lesions were KIT (CD117)-positive, but that the gastric lesion was CD34-positive, whereas the jejunal one was Vimentin-, S-100-, and SMA-positive. Molecular analysis of mutations in KIT exons 9, 11, 13, and 17, and in PDGFRA exons 12 and 18 revealed the presence of a gastric sporadic GIST with a KIT mutation of the exon 11 and a jejunal sporadic GIST without KIT or PDGFRA mutations. To our knowledge, this is the first report of laparoscopically resected synchronous sporadic gastric and jejunal GISTs.

c-Kit-negative fibroblast-like cells express platelet-derived growth factor receptor alpha in the murine gastrointestinal musculature

Platelet-derived growth factor receptors (PDGFRs) belong to the same kinase group as c-Kit receptor tyrosine kinase that is specifically expressed in the interstitial cells of Cajal (ICC) in the gastrointestinal tract. In this study, we examined PDGFRalpha immunoreactivity in the murine gastrointestinal tract. PDGFRalpha-immunopositive (PDGFRalpha-ip) cells were observed in the musculature in all parts of the gastrointestinal tract. Although PDGFRalpha-ip cells were distinct from ICC and neurons, these cells were closely associated with intramuscular ICC and enteric nerve fibers. In the myenteric layer, PDGFRalpha-ip cells formed a cellular network with their ramified processes and encompassed myenteric ganglia. Numerous PDGFRalpha-ip cells were observed in the subserosal plane and showed a multipolar shape. The distribution pattern of the PDGFRalpha-ip cells in the ICC-deficient W(v)/W(v) mutant mice was the same as that in normal mice. PDGFRalpha-ip cells that showed intense immunoreactivity of SK3 potassium channel were considered to correspond to fibroblast-like cells or non-Cajal interstitial cells. Our observations suggest that PDGFRalpha-ip cells are basic cellular elements throughout the gastrointestinal musculature and are involved in the gastrointestinal functions.