Gastrointestinal stromal tumors (GIST) in children and adolescents: A comprehensive review of the current literature

Surgical management of rare tumors (Part 1)

With an annual cumulative occurrence of approximately 15,000 in North America, all childhood cancers are rare. Very rare cancers as defined by both the European Cooperative Study Group for Rare Pediatric Cancers and the Children's Oncology Group fall into two principal categories: those so uncommon (fewer than 2 cases/million) that their study is challenging even through cooperative group efforts (e.g., pleuropulmonary blastoma and desmoplastic small round cell tumor) and those that are far more common in adults and therefore rarely studied in children (e.g., thyroid, melanoma, and gastrointestinal stromal tumor). Treatment strategies for these latter tumors are typically based on adult guidelines, although the pediatric variants of these tumors may harbor different genetic signatures and demonstrate different behavior. If melanoma and differentiated thyroid cancer are excluded, other rare cancer types account for only 2% of the cancers in children aged 0 to 14. This article highlights several of the most common rare tumor types.

A successful complete resection for multidrug-resistant giant gastrointestinal stromal tumor invading the transverse colon with multiple liver metastases in a young female: a case report

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are rare in young people and are often detected after becoming symptomatic or at an advanced stage. Herein, we report a case of complete reduction surgery for a substantially large malignant gastric GIST with multiple liver metastases in a young woman who successfully resulted in R0 surgery.

CASE PRESENTATION

An 18-year-old woman presented to our hospital with anorexia and vomiting, and was diagnosed with a 17 cm gastric GIST with transverse colon invasion and multiple liver metastases. Due to being considered unresectable, tyrosine and multi-kinase inhibitor therapy were administered up to the fourth line yielding no response. After careful discussion at a multidisciplinary team conference, pancreatoduodenectomy or distal gastrectomy, transverse colectomy, and resection of the liver metastases were planned. Consequently, distal gastrectomy, transverse colectomy, resection of the liver metastases, and incidental peritoneal metastases were performed. Although the primary goal of the surgery was to reduce the volume of the tumor as much as possible, the results revealed that the complete removal of all detectable tumors was achieved. No recurrence was observed after surgery for 27 months with long-term adjuvant imatinib therapy.

CONCLUSIONS

Even for highly advanced GISTs, aggressive surgery followed by adjuvant drug therapy may prolong survival in young patients.

Case report: detection of multiple sporadic gastrointestinal stromal tumors by dual-time 18 F-FDG PET/CT

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors affecting the gastrointestinal tract. Typically, GISTs are solitary; however, in rare cases, they may be multiple and appear in one or more organs. Multiple GISTs can appear in familial GISTs, children, or certain tumor syndromes such as neurofibromatosis type 1, Carney syndrome, and Carney-Stratakis syndrome. However, the diagnosis of primary multiple sporadic GISTs is often more difficult than that of these diseases. Herein, we report a case of multiple primary sporadic GISTs in a 64-year-old man, affecting the abdominal cavity and retroperitoneum, as identified through dual-time point positron emission tomography (PET) with 18F-labeled fluoro-2-deoxyglucose (18F-FDG) and computed tomography (18F-FDG PET/CT). Notably, the dual-time-point PET/CT revealed the migration of masses near the lower abdomen into the abdominal cavity. Furthermore, a significant increase in radioactive uptake of the mass 3 h after 18F-FDG injection compared with that 1 h after injection may be an important cue for its diagnosis.

A Rare Case of Terminal Ileum Gastrointestinal Stromal Tumor in a Young Caucasian Adult

Gastrointestinal stromal tumors (GISTs) are rare in young individuals and typically affect older adults. We present the case of a previously healthy male who presented with severe hematochezia, fatigue, and dizziness. Colonoscopy did not demonstrate any colonic mass. CT of the pelvis with contrast revealed a pelvic mass measuring 7.4 cm. Biopsy confirmed a low-grade mixed-type GIST of the terminal ileum. Surgical resection was successfully performed. Histopathological analysis further characterized the tumor, and the patient was discharged with consideration of adjuvant imatinib therapy. This case underscores the importance of thorough diagnostic evaluation and multidisciplinary management for atypical presentations of gastrointestinal bleeding in young patients.

Molecular Advances in the Treatment of Advanced Gastrointestinal Stromal Tumor

Most gastrointestinal stromal tumors (GIST) are driven by activating mutations in Proto-oncogene c-KIT (KIT) or PDGFRA receptor tyrosine kinases (RTK). The emergence of effective therapies targeting these mutations has revolutionized the management of advanced GIST. However, following initiation of first-line imatinib, a tyrosine kinase inhibitor (TKI), nearly all patients will develop resistance within 2 years through the emergence of secondary resistance mutations in KIT, typically in the Adenosine Triphosphate (ATP)-binding site or activation loop of the kinase domain. Moreover, some patients have de novo resistance to imatinib, such as those with mutations in PDGFRA exon 18 or those without KIT or PDGFRA mutation. To target resistance, research efforts are primarily focused on developing next-generation inhibitors of KIT and/or PDGFRA, which can inhibit alternate receptor conformations or unique mutations, and compounds that impact complimentary pathogenic processes or epigenetic events. Here, we review the literature on the medical management of high-risk localized and advanced GIST and provide an update on clinical trial approaches to this disease.

Precision Oncology in Gastrointestinal Stromal Tumors

GIST (gastrointestinal stromal tumors) represent 20% of sarcomatous tumors and 1-2% of primary gastrointestinal cancers. They have an excellent prognosis when localized and resectable, though their prognosis is poor in the metastatic setting, with limited options after the second line until recently. Four lines are now standard in KIT-mutated GIST and one in PDGFRA-mutated GIST. An exponential growth of new treatments is expected in this era of molecular diagnostic techniques and systematic sequencing. Currently, the main challenge remains the emergence of resistance linked to secondary mutations caused by selective pressure induced by TKIs. Repeating biopsies to tailor treatments might be a step in the right direction, and liquid biopsies at progression may offer a non-invasive alternative. New molecules with wider KIT inhibition are under investigation and could change the catalog and the sequence of existing treatments. Combination therapies may also be an approach to overcome current resistance mechanisms. Here, we review the current epidemiology and biology of GIST and discuss future management options, with an emphasis on genome-oriented therapies.

Latest Advances in the Management of Pediatric Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumor is the most common mesenchymal neoplasm of the gastrointestinal tract, usually found in elderly adults. It is infrequent among pediatric patients and usually differs biologically from adult-type diseases presenting mutations of KIT and PDGFR genes. In this population, more frequent is the wild-type GIST possessing SDH, TRK, RAS, NF1 mutations, among others. Both tumor types require individualized treatment with kinase inhibitors that are still being tested in the pediatric population due to the different neoplasm biology. We review the latest updates to the management of pediatric gastrointestinal tumors with a particular focus on the advances in molecular biology of the disease that enables the definition of possible resistance. Emerging treatment with kinase inhibitors that could serve as targeted therapy is discussed, especially with multikinase inhibitors of higher generation, the effectiveness of which has already been confirmed in the adult population.

The Management of Unresectable, Advanced Gastrointestinal Stromal Tumours

Gastrointestinal stromal tumours (GISTs) are the most common gastrointestinal tract mesenchymal tumours. Tyrosine kinase inhibitors (TKIs) have transformed the management of advanced GIST. Imatinib was the first TKI to gain approval as management for patients with advanced GIST, establishing a new standard of care. Since then, as a result of several trials including the GRID and INVICTUS studies, we now have five lines of approved targeted therapy, including imatinib, sunitinib, regorafenib, ripretinib and avapritinib for the treatment of unresectable, advanced GISTs. In this review, the Australasian Gastrointestinal Trials Group (AGITG) provide an overview of the key trials that have changed clinical practice, discuss the molecular drivers of GISTs, the importance of molecular testing and directing therapy according to molecular targets, as well as future strategies in the management of advanced GISTs.

Current treatment and outcomes of pediatric gastrointestinal stromal tumors (GIST): a systematic review of published studies

Gastrointestinal stromal tumor (GIST) is a rare cancer of mesenchymal origin mostly seen in adult and elderly populations. Therefore, the prognostic and therapeutic features of pediatric GIST are not clearly defined. Clinical knowledge has been largely extrapolated from case series and adult studies. In this systematic review, we aimed to analyze the health outcome metrics of pediatric GIST. Medline and Embase databases were searched using relevant key terms. The original search retrieved 1,892 titles; 27 studies with 184 patients (68% female) were included for final review. The primary tumors were located in the stomach (165/184, 90%), small bowel (12/184, 7%), and elsewhere (7/184, 4%). Individual patient data were available in 125 cases with a median follow-up of 6.7 years. All patients underwent surgical resection, which varied from wide local excision to total gastrectomy. There were 12 deaths (10%), 65 (52%) patients were alive with no evidence of disease, and 31 cases (25%) were alive with disease. Tumor size > 5 cm, high mitotic index, and spindle morphology were predictive of mortality. Pediatric GIST has a more favorable prognosis and different characteristics versus adult tumors. There is a crucial need for international consensus and specific pediatric guidelines for the treatment of this rare tumor.

Facing the challenges of very rare tumors of pediatric age: The European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) background, goals, and achievements

It has become increasingly clear in recent years that we need to develop ad hoc strategies to combat very rare tumors (VRT) of pediatric age. In 2008, several schemes being run in different countries were pooled together to create the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) project: a cooperative study group that aimed to promote research in the relatively uncharted territory of rare tumors of pediatric age. EXPeRT members were able to activate different levels of cooperation to achieve their goals, and to obtain dedicated funding by participating in EU-financed projects. Their experiences emphasize the merits of networking, seeking new partnerships, joining forces, and pooling resources to extend the reach of research efforts, and ultimately improve the quality of patient care. Between 2018 and 2021, the EXPeRT has been active in establishing the Pediatric Rare Tumors Network - European Registry (PARTNER). This project had the main purposes of building a European common registry of pediatric VRT, but also the major task of developing diagnostic and treatment guidelines for VRT (or at least part of them). These clinical recommendations are the subject of a series of papers on Pediatric Blood and Cancer.

Pediatric Gastrointestinal Stromal Tumors and Neuroendocrine Tumors: Advances in Surgical Management

Gastrointestinal stromal tumors and neuroendocrine tumors in adult and pediatric populations differ immensely. Despite these established differences, the extreme rarity of gastrointestinal stromal tumors and neuroendocrine tumors in the pediatric population has resulted in the lack of consensus management guidelines, making optimal surgical approaches unclear. Comprehensive management principles to guide surgical approaches in adult literature are extensive. However, these are still lacking for pediatric patients. International cooperation to develop standardized pediatric-specific guidelines is urgently warranted in the future. This article highlights the vast differences between adult and pediatric parameters and provides recommendations on optimal and novel surgical approaches in children.

Laparoscopic gastrectomy with lymph node dissection for the treatment of remnant stomach gastrointestinal stromal tumors in incomplete-type Carney's triad: a case report

BACKGROUND

We report a rare case of gastrointestinal stromal tumors (GISTs) in Carney's triad, successfully treated using laparoscopic gastrectomy with lymph node dissection after chemotherapy.

CASE PRESENTATION

A 21-year-old woman presented to our hospital for treatment of recurrent GISTs. The patient had been admitted for treatment 11 years prior, with black stools being the chief presenting complaint at that time. On examination at that time, multiple submucosal tumors in the pyloric antrum and multiple pulmonary tumors had been observed. She underwent open partial gastrectomy, and the diagnosis of GISTs was confirmed. She was administered tyrosine kinase inhibitors to treat lung metastases from 2 months after surgery. Due to the increasing size of the lung tumors, a right upper lobectomy was performed 9 years after the index gastric surgery. Histopathological examination of the lung specimen, in combination with re-examination of the gastric specimens, was indicative of incomplete-type Carney's triad. Eleven years after the index gastric surgery, multiple GISTs were observed in her entire stomach. Tumor biopsy revealed a succinate dehydrogenase deficiency, confirming the diagnosis of recurrent GISTs. For treatment, the patient underwent laparoscopic completion gastrectomy, with D1 plus lymph node dissection.

CONCLUSION

This is a first case report of completion gastrectomy performed laparoscopically for the treatment of GISTs associated with incomplete-type Carney's triad. The recurrent GISTs developed over a protracted period of 11 years from the index gastric surgery to tumor recurrence.

BRD4 promotes tumor progression and NF-κB/CCL2-dependent tumor-associated macrophage recruitment in GIST

The most commonly occurring sarcoma of the soft tissue is gastrointestinal stromal tumor (GIST). Treatment and prevention of the disease necessitate an understanding of the molecular mechanisms involved. However, the role of BRD4 in the progression of GIST is still unclear. While it is known there are abundant infiltrating tumor-associated macrophages (TAMs) in the tumor microenvironment, the exact role of these cells has yet to be studied. This work showed an upregulation of BRD4 in GIST that was associated with GIST prognosis. Through gain and loss of function studies, it was found that BRD4 promotes GIST growth and angiogenesis in vitro and in vivo. Mechanistically, BRD4 enhances CCL2 expression by activating the NF-κB signaling pathway. Furthermore, this CCL2 upregulation causes recruitment of macrophages into the tumor leading to tumor growth. A likely mechanism for interactions in the GIST microenvironment has been outlined by this work to show the role and potential use of BRD4 as a treatment target in GIST.

Non-exposed endoscopic wall-inversion surgery for pediatric gastrointestinal stromal tumor: A case report

Gastrointestinal stromal tumors (GIST) in patients under 18 years of age are classified as pediatric GIST. Pediatric GIST are extremely rare, and there are no reports of laparoscopic-endoscopic cooperative surgery for these lesions. We report the use of non-exposed endoscopic wall-inversion surgery as a laparoscopic-endoscopic cooperative surgery-related procedure for the treatment of a pediatric GIST. The case involved a 17-year-old male patient who presented with anemia and was found to have a bleeding gastric tumor. The tumor was resected transorally using the non-exposed endoscopic wall-inversion surgery technique. No gene mutation of c-Kit or Platelet-Derived Growth Factor Receptor α (PDGFRα) was found, and the final pathological diagnosis was epithelial-type GIST due to a succinate dehydrogenase abnormality. Follow-up included a CT scan every 4 months. No recurrence has occurred to date.

Sunitinib in pediatric patients with advanced gastrointestinal stromal tumor: results from a phase I/II trial

BACKGROUND

Sunitinib is approved for treatment of adults with imatinib-resistant gastrointestinal stromal tumor (GIST) or imatinib intolerance.

METHODS

This single-arm, multicenter, multinational phase I/II clinical trial (NCT01396148) enrolled eligible patients aged 6 to < 18 years with advanced, unresectable GIST with non-mutant KIT, or who demonstrated disease progression or intolerance to imatinib. Patients received sunitinib 15 mg/m² per day, 4-weeks-on/2-weeks-off (schedule 4/2), for ≤ 18 cycles over 24 months. Intra-patient dose escalation to 22.5 and subsequently 30 mg/m² were permitted based on individual patient tolerability and supported by real-time pharmacokinetics (PK). Primary objective was PK characterization. Secondary objectives included safety, antitumor activity and PK/pharmacodynamic relationships.

RESULTS

Six patients were enrolled with median (range) age of 14 (13-16) years. All six patients completed at least three treatment cycles, with one completing all 18 cycles. Five patients had a dose increase to 22.5 mg/m²; two of them had a further dose increase to 30 mg/m². The average daily dose at cycle 3 was 21.1 mg/m² (n = 6). Steady-state plasma concentrations were reached by day 15, cycle 1. No tumor responses were observed, but three patients had stabilization of the disease (50%). Median progression-free survival was 5.8 months (95% CI 2.3-not reached). There were no serious adverse events.

CONCLUSIONS

The tolerable dose of sunitinib in chemotherapy-naïve pediatric patients is at least 20 mg/m² on schedule 4/2. The safety profile and PK of sunitinib in pediatric patients with GIST are comparable to those in adults.

A 4-month-old boy with gastrointestinal stromal tumor of mesocolon

Gastrointestinal stromal tumors (GISTs) are very uncommon in pediatric patients, and they are distinct clinical-pathological and molecular deviations from their adult counterparts. Most pediatric GISTs lack the c-kit or platelet-derived growth factor receptor alpha (PDGFRA) genes mutations. To date, there is no published standard guidelines available for the best treatment of pediatric GISTs, especially for infant GIST. Therefore, we report a case of 4-month-old infant with GIST of mesocolon without KIT/PDGFRA mutation. We also review the clinical, biological, and genetic features of pediatric GISTs and re-think several questions that could affect clinical practice.

Imaging pediatric gastrointestinal stromal tumor (GIST)

BACKGROUND

Gastrointestinal stromal tumors (GIST) are extremely rare in children. Imaging plays a key role in staging and monitoring therapy (surgical and with tyrosine kinase inhibitors). The vast majority of articles addressing imaging of GIST base on adults and are based on CT. The subtype "pediatric GIST" - if at all - is only mentioned in a dependent clause. Although the imaging features in children and adults are similar, histology, clinical course and thus imaging approach are different.

METHODS

A PubMed search using the search terms "Gastrointestinal stromal tumor, GIST, WT GIST, children, pediatric, carney's triad, imaging, staging, follow-up, MRI, CEUS, ultrasonography, Positron emission tomography" was conducted. Studies that reported on laparoscopy, endoscopy and surgical techniques only were excluded.

RESULTS

Based on our selective literature review, we present alternative radiological imaging strategies using MRI, contrast enhanced ultrasound (CEUS) and PET-CT to stage and follow-up pediatric GIST patients. As pediatric GIST often is a chronic disease, minimizing exposure to ionizing radiation is mandatory.

CONCLUSION

MRI, contrast enhanced ultrasound and PET-CT instead of CT are the imaging modalities to evaluate pediatric GIST.

TYPE OF STUDY

Systematic review LEVEL OF EVIDENCE: III.

Current treatment strategies in pediatric gastrointestinal stromal cell tumor

Gastrointestinal stromal tumors (GIST) are exceedingly rare tumors in the pediatric population. As a result, many clinicians either may never see this diagnosis or will encounter it only a few times throughout their careers. Additionally, the more we discover about this disease, it becomes evident that it represents a distinct clinical entity from adult GIST. Many of the treatments and strategies used to combat the adult tumor are either ineffective or may be harmful to the pediatric population with this disease. The unique tumor biology found in pediatric GIST necessitates unique approaches and treatment strategies in order to achieve the best clinical outcome. This review aims to discuss the most recent data available on the different therapeutic modalities utilized in cases of Pediatric GIST.

Endoscopic ultrasound FNA: An illustrated review of spindle cell neoplasms of the upper gastrointestinal tract including a novel case of gastric plexiform fibromyxoma

Plexiform fibromyxoma (PF) is a recently-described and rare mesenchymal neoplasm of the gastric wall. A few small case series reports of this spindle cell entity exist in the surgical pathology literature, but to our knowledge no prior endoscopic ultrasound guided fine needle aspiration cytology examples have been reported. In clinical practice, mural gastrointestinal (GI) lesions are often initially evaluated by endoscopic ultrasound guided (EUS) fine needle aspiration (FNA). In addition, newer EUS fine needle biopsy techniques also allow for reliable retrieval of core tissue samples with intact cellular architecture, making EUS histopathologic analyses possible. We report a combined EUS FNA and core biopsy case of PF and correlate the findings with imaging results. The cytomorphology of PF is described and illustrated, and important entities in the differential diagnosis of upper GI spindle cell lesions (including GI stromal tumor, leiomyoma, schwannoma, carcinoid tumor, desmoid-type fibromatosis, and inflammatory fibroid polyp) are reviewed. Illustrated examples of relevant cytomorphologic, cell block histomorphologic and immunohistochemical characteristics are emphasized.

Pediatric Cancer Predisposition Imaging: Focus on Whole-Body MRI

The American Association for Cancer Research convened a meeting of international pediatric oncologists, geneticists, genetic counselors, and radiologists expert in childhood cancer predisposition syndromes (CPS) in October 2016 to propose consensus surveillance guidelines. Imaging plays a central role in surveillance for most, though not all, syndromes discussed. While encompassing the full gamut of modalities, there is increasing emphasis on use of nonionizing radiation imaging options such as magnetic resonance imaging (MRI) in children and adolescents, especially in the pediatric CPS population. In view of rapid evolution and widespread adoption of whole-body MRI (WBMRI), the purpose of our review is to address WBMRI in detail. We discuss its place in the surveillance of a range of pediatric CPS, the technical and logistical aspects of acquiring and interpreting these studies, and the inherent limitations of WBMRI. We also address issues associated with sedation and use of gadolinium-based contrast agents in MRI in children. Clin Cancer Res; 23(11); e6-e13. ©2017 AACRSee all articles in the online-only CCR Pediatric Oncology Series.

Pediatric GIST presenting as anemia

Gastrointestinal stromal tumors (GIST) are tumors of the gastrointestinal (GI) tract originating from the myenteric ganglion cells (interstitial cells of Cajal), that are very rare in children and adolescents. The most common clinical manifestation is acute or chronic, overt or occult GI bleeding although these tumors are asymptomatic in 10-30% of patients. We report a case of gastric GIST in a 11-year-old girl presenting with an iron deficiency refractory anemia without gastrointestinal symptoms and stool evidence of GI bleeding that caused a slight diagnostic delay.

Gastrointestinal stromal tumours (GISTs): an insight into clinical practice with review of literature

BACKGROUND

Gastrointestinal stromal tumours (GISTs) are rare mesenchymal tumours of the gastrointestinal tract. We retrospectively reviewed the clinical management of all patients with GIST presenting to a regional multidisciplinary upper gastrointestinal cancer group in the north of England.

METHODS

Clinical, pathological, immunohistochemical treatment strategies, follow-up and outcome data on all patients with GIST between 2007 and 2012 were reviewed. Tumours were categorised by risk according to the National Institutes of Health (NIH) and AFIP models.

RESULTS

36 (85.7%) of 42 tumours were located in the stomach, 5 (11.9%) in the small intestine and 1 (2.4%) in the oesophagus. Median age of patients was 68 (range 43-91) years. 24 patients (57.1%) were female. Tumour size ranged from 1.0  to 12.7 cm with mean size of 5.46 cm. Metastasis was present in 19 (45.2%) patients at diagnosis with distant metastases in 12 patients. Liver was the most common site of metastases. Histology and immunohistochemical analysis was available in 32 (76.2%) patients. Most common histology was spindle cell morphology 17/32 (53.1%) followed by epithelioid 9/32 (28.1%) and mixed morphology 5/32 (15.6%). The positive rate for KIT protein (CD117) was 90.6%, while that for CD34 was 75.0%. 12/25 (48.0%) and 8/23 (34.8%) patients were categorised as high risk as per NIH and AFIP risk scores, respectively. 23/42 (54.8%) patients underwent surgical resection, after which 5/23 (21.7%) had adjuvant imatinib therapy. Imatinib was given as primary therapy in 14/42 (33.3%) patients.

CONCLUSIONS

Surgery alone may not be a curative treatment for GISTs. Targeted therapy with imatinib may play an important role in the treatment of GISTs. Further risk categorisation models may be needed to evaluate GIST behaviour and prognosis.

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.

Pediatric/"Wildtype" gastrointestinal stromal tumors

Pediatric/"Wildtype" gastrointestinal stromal tumor (P/WT-GIST) is a rare cancer, distinct and markedly different from the phenotype found predominantly in older patients (adult, non-wildtype GIST). Having a different molecular signature, it is not responsive to standard adjuvant therapies utilized in adult GIST, and surgery remains the only effective cure. However, even with presumed complete resections in patients with localized disease at presentation, recurrence rates are high. Furthermore, it is an indolent cancer that can persist for decades, and treatment strategies must balance the possible morbid risks of intervention with the reality of preserving quality of life in the interim. Effective adjuvant therapies remain elusive, and research is critically needed to identify both targets and drugs for treatment consideration.

Syndrome-Associated Tumors by Organ System

Certain tumors suggest the possibility of a patient harboring a genetic syndrome, particularly in children. Syndrome-associated tumors of the gastrointestinal tract, genitourinary tract, gynecologic tract, heart, lungs, brain, eye, endocrine organs, and hematopoietic system will be briefly discussed.

Laparoscopic resection of a rare gastrointestinal stromal tumor in children

Introduction

Gastrointestinal stromal tumors (GIST) are uncommon mesenchymal tumors of the gastrointestinal (GI) tract, accounting for 0.1% to 3% of all GI malignancies. Paediatric GIST have an annual incidence of 0.02 per million children, have a female predisposition, are usually located in the stomach (50–60%) and in up to 85% of cases CD117-cKit or PDGFRA mutation is absent, resulting in a decreased efficacy of the target therapy.

Case description

We report the case of an incidentally diagnosed gastric GIST in a 14-year-old boy with multiple malformations. Genetic tests and Kariotype resulted negative.

Recently, an abdominal US visualized an hypoechoic heterogeneous abdominal mass. The common tumor markers resulted negative and the abdominal CT-scan confirmed the presence of a solid round lesion (42×36mm) in contact with the stomach and the pancreas. Laparoscopy allowed the recognition and the removal of the nodular mass at the posterior margin of the stomach. The histopathologic and the molecular biology findings were consistent with a kit-wilde type GIST. Surgical margins were microscopically free of tumor cells.

These results justify the decision not to add other surgical or medical therapy. However, for high risk of recurrence and metastasis, a close follow-up was started.

Discussion and evaluation

GIST are asymptomatic in 10% to 30% of patients or present nonspecific symptoms and signs. These tumors present usually irregular, lobulated and ulcerated. CT-scan of the abdomen and pelvis or magnetic resonance imaging (MRI) are mandatory in the diagnostic work-up. The final diagnosis is based on histology and immunohistochemistry. Surgery is the first-line treatment in patients with localized disease.

Conclusion

Guidelines for the management of pediatric GIST are not presently available for the paucity of reports and data. However it is widely accepted that surgery is the first-line treatment and gross resection with negative microscopic margins can be considered therapeutic and lead to full remission of the pathology. Laparoscopy is a safe surgical approach for the exploration of the abdominal cavity, the evaluation of the disease and the complete removal of the tumor.

Gastrointestinal stromal tumor in a newborn diagnosed in prenatal period: a case report and review of literature

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the gastrointestinal tract. Only 1.5% to 2% of all GISTs are observed in children and adolescents. Most of the pediatric cases are between 10 and 18 years of age, with a median age of 13 years. GIST is extremely rare in the newborn period. We could find only 5 reports on the neonatal cases. Herein, we have reported a case with abdominal tumor that was identified by prenatal ultrasonography and magnetic resonance imaging, and diagnosed as GIST on the seventh day of life. We have also reviewed the neonatal GIST cases reported in the English literature.

Incidental GIST after appendectomy in a pediatric patient: a first instance and review of pediatric patients with CD117 confirmed GISTs

A 7-year-old boy underwent uncomplicated laparoscopic appendectomy for acute appendicitis. Incidentally, he was found to have a spindle cell tumor with CD117 immunopositivity, consistent with gastrointestinal stromal tumor (GIST) in the appendix. Although commonly reported in adults, pediatric GISTs are rare gastrointestinal malignancies that occur in only 1.4-2.7% of children and adolescents. Due to the paucity of reports, data are insufficient to adequately characterize tumor behavior, recurrence, and survival. We present the first case of pediatric GIST in the appendix. In addition, a review of the literature for CD117 confirmed pediatric GISTs was conducted to summarize its clinical features and current treatment options.

Massive intra-abdominal imatinib-resistant gastrointestinal stromal tumor in a 21-year-old male

Gastrointestinal stromal tumors (GISTs) in adolescence are far less common than adult GISTs and have varied GIST genotypes that present diagnostic and therapeutic challenges. Here, we discuss a 21-year-old male with diagnosis of unresectable, imatinib-resistant GIST. At initial evaluation, a neoadjuvant treatment approach was recommended. As such, the patient received imatinib over the course of one year. Unfortunately, the GIST increased in size, and a subsequent attempt at surgical resection was aborted fearing infiltration of major vascular structures. The patient was then referred to our institution, at which time imatinib therapy was discontinued. Surgical intervention was again considered and the patient underwent successful resection of massive intra-abdominal GIST with total gastrectomy and Roux-en-Y esophagojejunostomy. Since pediatric GISTs are typically resistant to imatinib, we performed genotype analysis of the operative specimen that revealed KIT mutations associated with imatinib sensitivity and resistance. Given the sequencing data and operative findings, the patient was started postoperatively on sunitinib. This case illustrates the importance of understanding both adult and pediatric GISTs when implementing appropriate treatment regimens. Since the genotype of GISTs dictates phenotypic behavior, mutational analysis is an important component of care especially for adolescents whose disease may mirror the pediatric or adult population.

Succinate dehydrogenase deficiency in pediatric and adult gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) in adults are generally driven by somatic gain-of-function mutations in KIT or PDGFRA, and biological therapies targeted to these receptor tyrosine kinases comprise part of the treatment regimen for metastatic and inoperable GISTs. A minority (10-15%) of GISTs in adults, along with ∼85% of pediatric GISTs, lacks oncogenic mutations in KIT and PDGFRA. Not surprisingly these wild type (WT) GISTs respond poorly to kinase inhibitor therapy. A subset of WT GISTs shares a set of distinguishing clinical and pathological features, and a flurry of recent reports has convincingly demonstrated shared molecular characteristics. These GISTs have a distinct transcriptional profile including over-expression of the insulin-like growth factor-1 receptor, and exhibit deficiency in the succinate dehydrogenase (SDH) enzyme complex. The latter is often but not always linked to bi-allelic inactivation of SDH subunit genes, particularly SDHA. This review will summarize the molecular, pathological, and clinical connections that link this group of SDH-deficient neoplasms, and offer a view toward understanding the underlying biology of the disease and the therapeutic challenges implicit to this biology.

Soft tissue tumors of uncertain origin

Many soft tissue tumors of childhood lack obvious differentiation toward a defined mesenchymal tissue type or have a phenotype that does not correspond to any defined normal tissue. These challenging tumors are currently regarded as neoplasms of uncertain differentiation. Nonetheless, there have been great strides in the understanding of their pathologic and genetic features and biologic underpinnings. The application of new genetic information to the pathologic diagnosis among this group of tumors is an emerging area in diagnostic pediatric pathology. This article reviews the clinicopathologic features of tumors of uncertain and/or miscellaneous origin, with an emphasis on the unique aspects of these neoplasms in children and adolescents, use of diagnostic adjuncts, and differential diagnosis.

Pediatric Gastrointestinal Tumors

Gastrointestinal stromal tumors or GISTs belong to a category of gastrointestinal mesenchymal tumors that can have benign or malignant potential. These tumors were formerly identified as gastrointestinal (GI) leiomyomas, leiomyoblastomas, or leiomyosarcomas. GISTs account for approximately 80% of GI mesenchymal tumors and 3% of all childhood tumors. Pediatric GISTs occur in patients younger than 18 years and are extremely rare. In the United States, pediatric GISTs have been reported in the literature less than 100 times. In addition, much research has failed to distinguish between benign and malignant mesenchymal tumors. This makes it extremely difficult for medical professionals to develop any type of expertise because few see more than one or two of these cases in a career, and of those cases, many never differentiate between the two. This case study involves a young patient who had been diagnosed with pediatric GIST. This report details the initial sonographic findings and the follow-up studies that had initially suggested a pediatric GIST of malignant potential but, upon further outside consultation, suggested a benign pediatric GIST.

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.

Pediatric gastrointestinal stromal tumor

Pediatric gastrointestinal stromal tumor (GIST) is a rare entity that can be quite different from its adult counterpart. This report provides a comprehensive review on the diagnosis and management of this tumor in children and adolescents, including its oncogenesis and associated syndromes. Surgery remains a mainstay of treatment, but there are no standard guidelines available at this time regarding the best practice for multimodality therapy as our understanding of the biology of GIST is still in evolution. Therefore, pediatric patients with GIST should be ideally treated in the context of clinical trials at specialized, multidisciplinary centers throughout the course of their disease, especially because these patients may live for years after diagnosis.

[Gastrointestinal stromal tumors]

Gastrointestinal stromal tumors (GIST) are the most common sarcomas of the gastrointestinal tract. They affect all segments of the digestive tract. They develop from the interstitial cells of Cajal. Mutations in the Kit gene is present in 86% of cases and in PDGFR gene in 15% of cases. The marker CD 117 is present in 95% of cases. Surgery is the standard treatment in localized forms. The tyrosine kinase inhibitor, imatinib is standard in first-line metastatic gastrointestinal stromal tumors, as well as adjuvant treatment after surgery. Sunitinib is the standard in second line.

Special considerations in pediatric gastrointestinal tumors

Pediatric gastrointestinal tumors are rare in children but are being increasingly recognized. These tumors have distinct biologic and clinical feature that are different from those observed in adults. This review highlights the biological and clinical characteristics of pediatric GIST and provides diagnostic and therapeutic guidelines for the management these unique and challenging group of tumors.

Gastrointestinal stromal tumor: advances in diagnosis and management

CONTEXT

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract and should be differentiated from other mesenchymal tumors. They harbor specific activating mutations in the KIT or platelet-derived growth factor receptor α ( PDGFRA ) receptor tyrosine kinases, which makes them responsive to pharmacologic inhibitors, such as imatinib mesylate and sunitinib malate.

OBJECTIVES

To provide a comprehensive review of the pathogenesis of GIST and the underlying principles of targeted therapy, to review the salient histologic and immunohistochemical features that facilitate the distinction of GIST from other mesenchymal neoplasms of the gastrointestinal tract, and to present the prognostic parameters for risk stratification that guide clinical management.

DATA SOURCES

Review of the English literature through PubMed as well as personal experience. Photographs were taken from cases encountered at the Cleveland Clinic.

CONCLUSIONS

The discovery of the KIT -GIST connection has not only improved the diagnostic accuracy of GISTs but also provided us with a better understanding of the histogenesis and molecular pathogenesis of these neoplasms.