[Gastrointestinal stromal tumors: definition, histological, immunohistochemical, and molecular features, and diagnostic strategy]

Advances in the diagnosis and treatment of MET-variant digestive tract tumors

The receptor tyrosine kinase encoded by the MET gene plays an important role in various cellular processes such as growth, survival, migration and angiogenesis, and its abnormal activation is closely related to the occurrence and development of various tumors. This article reviews the recent advances in diagnosis and treatment of MET-variant digestive tract tumors. In terms of diagnosis, the application of next-generation sequencing technology and liquid biopsy technology makes the detection of MET variants more accurate and efficient, providing a reliable basis for individualized treatment. In terms of treatment, MET inhibitors such as crizotinib and cabotinib have shown good efficacy in clinical trials. In addition, the combination of immunotherapy and MET inhibitors also demonstrated potential synergies, further improving the therapeutic effect. However, the complexity and heterogeneity of drug resistance mechanisms are still one of the difficulties in current research. In the future, it is necessary to further deepen the understanding of the mechanism of MET variation and explore new combination treatment strategies to improve the overall survival rate and quality of life of patients. The diagnosis and treatment of MET-variant digestive tract tumors are moving towards precision and individualization, and have broad application prospects.

[Gastrointestinal Stromal Tumors "GIST": status and news through our experience on 54 cases and review of literature]

Les Tumeurs Stromales Gastro-intestinales « GIST » sont une forme très rare de cancers du tube digestif appartenant à la famille des sarcomes. Le but de ce travail est d'établir le profil épidémiologique et évolutif ainsi que les difficultés diagnostique et thérapeutique de cette pathologie maligne prise en charge dans un pays en développement. Une Etude rétrospective étalée sur 8 ans de Janvier 2002 à Mars 2010, a été mené au Service de Radiothérapie et d'Oncologie du CHU de Casablanca (Maroc) ayant colligée 54 cas de tumeurs stromales gastro-intestinales. L'âge moyen de nos patients était de 55 ans. Le délai moyen d'évolution était de 11 mois (0-72 mois). La biopsie a permis de confirmer le diagnostic dans 14 cas et la chirurgie dans 40 cas. La principale forme histologique était fusiforme (92,6%). Les GIST dans notre série avaient une taille tumorale moyenne de 12,5 cm avec un C-Kit positif dans 52 cas. Le risque évolutif a pu être établi dans 47 cas dont 39 avaient un risque élevé. La chirurgie était le principal traitement des patients de notre sérieAprès un recul moyen de 31 mois, la moitié des patients évaluables de notre série (n=19) est en rémission complète maintenue, le tiers (n=13) est décédé alors que le quart (n=8) présente une récidive locale et /ou métastatique. Quoique les recommandations soient éditées pour la prise en charge de ces tumeurs, ces dernières soulèvent encore de nombreux problèmes aussi bien diagnostiques que thérapeutiques dans notre contexte.

LAPAROENDOSCOPIC TRANSGASTRIC RESECTION OF SUBEPITHELIAL JUXTACARDIAC TUMORS

BACKGROUND

With a prevalence of 0.4-3.5%, subepithelial lesions of the upper digestive tract are discovered during endoscopic procedures. Treatment depends on etiological and pathophysiological information, ability to diagnose and the different technical resources available.

AIM

To demonstrate the effectiveness of a surgical technique that combines endoscopy and videolaparoscopy in the transgastric resection of subepithelial juxtacardic lesions.

METHOD

The patients were assisted with a technical combination between endoscopy and laparoscopy. After diagnosis of subepithelial tumor, intraoperative endoscopy was performed after pneumoperitoneum and placement of laparoscopic tweezers. Through endoscopy, the following steps were performed: demarcation of surgical margins, visualization of the intragastric image for the laparoscopic procedure and removal of the surgical specimen. By laparoscopy the following steps were performed: intragastric intra-abdominal access, resection of the part and closure of the gaps.

RESULTS

This technique was applied in two cases in order to evaluate its initial results. There were two videolaparoendoscopic resections of juxtacardiac gastric tumors of the posterior wall. Both had their endoscopic diagnosis confirmed. After laparoendoscopic and tomographic and/or ecoendoscopic diagnostic complementation and preoperative performance, the laparoendoscopic procedure was indicated. The patients had a good recovery, with a short hospitalization time and no complications.

CONCLUSION

The combined use of videolaparoscopy and endoscopy is a safe and effective technique for transgastric resection of juxtacardiac subepithelial lesions. It may be important for definitive diagnosis of the tumor.

Gastrointestinal stromal tumors (GISTs): SEAP-SEOM consensus on pathologic and molecular diagnosis

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the digestive tract, with an incidence of 1.1 cases/100,000 inhabitants/year. A group of experts from the Spanish Society of Pathology and the Spanish Society of Oncology met to discuss a brief update on GISTs and agree on aspects relating to the pathological and molecular diagnosis of these tumors. GISTs are generally solitary, well-circumscribed lesions of variable size (<10 mm-35 cm) that may present with intra- or extra-luminal parietal growth or a mixed-type (hourglass) growth pattern. Histologically, they are unencapsulated neoplasms displaying expansive growth and spindle-shaped (70%), epithelioid (20%), or mixed cellularity (10%). Mitotic activity is generally moderate or low and should be evaluated only in areas with high cellularity or higher mitotic frequency. The great majority of GISTs harbour mutually exclusive activating mutations in genes coding for the type III receptor tyrosine kinases KIT and PDGFRA; less commonly, GISTs have also been reported to display mutations elsewhere, including BRAF and NF1 and SDH-complex genes. The method most widely used to detect KIT and PDGFRA mutations is amplification of the exons involved by polymerase chain reaction followed by direct sequencing (Sanger method) of these amplification products. Molecular analyses should always specify the type of analysis performed, the region or mutations evaluated, and the sensitivity of the detection method employed.

Gastrointestinal Stromal Tumors: A Clinicopathologic and Risk Stratification Study of 255 Cases from Pakistan and Review of Literature

PURPOSE

To describe the clinicopathological features of gastrointestinal stromal tumors (GIST) diagnosed in our section and to perform risk stratification of our cases by assigning them to specific risk categories and groups for disease progression based on proposals by Fletcher et al and Miettinen and Lasota.

MATERIALS AND RESULTS

We retrieved 255 cases of GIST diagnosed between 2003 and 2014. Over 59% were male. The age range was 16 to 83 years with a mean of 51 years. Over 70% occurred between 40 and 70 years of age. Average diameter of tumors was 10 cms. The stomach was the most common site accounting for about 40%. EGISTs constituted about 16%. On histologic examination, spindle cell morphology was seen in almost of 85% cases. CD117 was the most useful immunohistochemical antibody, positive in 98%. Risk stratification was possible for 220 cases. Based on Fletcher's consensus proposal, 62.3 gastric, 81.8% duodenal, 68% small intestinal, 72% colorectal and 89% EGISTs were assigned to the high risk category; while based on Miettinen and Lasota's algorithm, about 48% gastric, 100% duodenal, 76% small intestinal, 100% colorectal and 100% EGISTs in our study were associated with high risk for disease progression, tumor metastasis and tumor related death. Follow up was available in 95 patients; 26 were dead and 69 alive at follow up. Most of the patients who died had high risk disease and on average death occurred just a few months to a maximum of one to two years after initial surgical resection.

CONCLUSIONS

Epidemiological and morphologic findings in our study were similar to international published data. The majority of cases in our study belonged to the high risk category.

[Gastro-intestinal neuroectodermal tumor (GNET): A case report of a small intestine tumor with hepatic metastases]

The gastro-intestinal neuroectodermal tumor (GNET) is a rare sarcoma of the digestive tract, which was recently recognised. The knowledge of the morphological, immunohistochemical and molecular diagnostic criteria is necessary to not mistake it for the metastasis of a melanoma or for another sarcoma of the digestive tract as the gastro-intestinal clear cells sarcoma or the malignant peripheral nervous system tumor (MPNST). We report the case of a 41-year-old patient with a GNET of the small intestine with hepatic metastasis. The histological examination showed a diffuse proliferation of epithelioid cells, which only express PS100. The presence EWSR1-ATF1 gene fusions with any melanocytic differentiation leads to the diagnosis of GNET.

[Gastrointestinal stromal tumor of the ileum with metastatic relapse developed in the mesentery]

Nous rapportons le cas d'un homme de 29 ans admis pour une masse hypogastrique très douloureuse. La laparotomie exploratrice réalisée en urgence permettait de mettre en évidence l'origine et la localisation iléale de la masse tumorale. Le traitement chirurgical consistait en une tumorectomie complète avec respect des marges carcinologiques. Les suites opératoires étaient simples et l'examen histologique confirmait la nature stromale de la tumeur iléale réséquée. Les marges de résection passaient en tissus sains. Le patient était perdu de vue et n'ayant reçu aucun traitement adjuvant. Un an plus tard, il est revenu pour ballonnement et masse pelviens d’évolution rapidement progressive et dont l'exploration chirurgicale révélait l'existence d'une tumeur mésentérique. Une tumorectomie était réalisée mais incomplète à cause d'une perte sanguine avec instabilité hémodynamique induite par l'exérèse tumorale. Après analyse histologique et immunohistochimique de la pièce opératoire, le diagnostic d'une tumeur stromale était confirmé. Il s'agissait d'une rechute métastatique à localisation mésentérique d'une tumeur stromale digestive d'origine iléale à fort potentiel malin. La réduction tumorale suivie d'un complément thérapeutique par l'Imatinib (glivec^®) permettaient d'obtenir un résultat satisfaisant. Avec un recul de 12 mois, le patient était asymptomatique et aucune récidive locale ni de métastase à distance n'a été observée.

[Gastrointestinal stromal tumors (GIST): at the forefront of targeted therapies]

Although gastrointestinal stromal tumors (GIST) are the most frequent sarcomas, they were usually not diagnosed before 1998. GIST derive from interstitial cells of Cajal, and may develop along the digestive tract, mainly from stomach and small intestine. GIST are characterized by the expression of KIT (CD117), and mutations KIT or PDGFRA are present in 85 % of cases. More than 150 different types of mutations have been reported. They are responsible for a constitutive activation of these tyrosine kinase receptors, in absence of their specific ligand. Detection of these mutations may help to confirm the diagnosis or to evaluate the prognosis. The mutations also have a predictive value. Indeed patients with metastatic GIST and duplication within exon 9 of KIT deserve to receive twice the dose of imatinib, while GIST with PDGFRA p.D842 V mutation are resistant to this drug. This review presents the main characteristics of GIST, and focus on the important insights of studies on GIST and their cell models in the field of oncology.

[Gastrointestinal stromal tumours in pediatrics: a summary of the literature on this orphan disease]

Recommendations for the management of gastrointestinal stromal tumours (GIST) in children and adolescents do presently not exist. Thus, a summary of the current literature was conducted serving as a basis for the development of optimal management strategies for childhood GIST. Pediatric cases of GIST may occur sporadically, or within a predisposition syndrome such as Carney triad or Carney-Stratakis syndrome. Moreover, cases with familial GIST have been reported. The frequency of mutations of the oncogenes KIT and PDGFRα in sporadic GIST is substantially lower as compared with adults with GIST. An international prospective registration based on national registries has recently been started in order to acquire more clinical and molecular data and to develop appropriate management strategies for children and adolescents with GIST.

[North African and Southeast Asian nasopharyngeal carcinomas: between the resemblance and the dissemblance]

Nasopharyngeal carcinoma (NPC) is an unusual head and neck cancer because of its unequal geographical distribution and its consistent association with the Epstein-Barr virus (EBV). This malignant tumor poses a serious public health problem in many countries, especially in Southeast Asia and North Africa where the recorded incidence are highest. During the past decade, a growing number of studies were undertaken to define the molecular basis of NPC. However, the analysis of several clinical and biological parameters of North African and Southeast Asian NPCs has shown notable differences, suggesting that they could result from a distinct combination of etiological factors. One intriguing characteristic of North African NPC, concerns its bimodal age distribution with a secondary peak of incidence in the range of 15-25 years, not observed in Asian NPC. In this juvenile form of NPC, immuno-histochemistry assay has shown that the two key proteins controlling the apoptotic-survival balance p53 and Bcl-2 are less frequently expressed whereas the transmembrane tyrosine-kinase receptor c-kit and the main EBV oncoprotein LMP1 were more abundant. In addition, the EBV serological alterations are less informative for the diagnosis of the juvenile compared to the adult form. In addition, most North African NPCs contain EBV strains with genetic polymorphisms distinct from those described in the Southeast Asia series (predominance of F, D, H1-H2, XhoI+ and f, C, H, XhoI- respectively). In contrast, studies relating on tumor chromosomal alterations or aberrant promoter methylation result in data very similar to those obtained from the Southeast Asia series, supporting the concept of a common molecular basis for all NPC regardless of patient geographic origin.

The Merendino procedure following preoperative imatinib mesylate for locally advanced gastrointestinal stromal tumor of the esophagogastric junction

BACKGROUND

Gastrointestinal stromal tumors (GIST) of the esophagogastric junction might pose a major problem to surgical resection. If locally advanced, extended or multivisceral resection with relevant procedural-specific morbidity and mortality is often necessary.

CASE PRESENTATION

We report a case of a patient with a locally advanced GIST of the esophagogastric junction who was treated by transhiatal resection of the lower esophagus and gastric cardia with reconstruction by interposition of segment of the jejunum (Merendino procedure). Prior to resection, downsizing of the tumor had successfully been achieved by treatment with imatinib mesylate for six months. Histological proof of GIST by immunohistochemical expression of c-KIT and/or PDGF alpha Receptor is crucial to allow embarking on this treatment strategy.

CONCLUSION

A multimodal approach for an advanced GIST of the esophagogastric junction with preoperative administration of imatinib mesylate could avoid extended resection. The Merendino procedure might be considered as the reconstruction method of choice after resection of GIST at this location.

[Not Available]

J.-F. Emile Gastrointestinal stromal tumors (GIST) are the most frequent mesenchymal tumours of the digestive tract. They can arise anywhere in the gastrointestinal tract, from oesophagus to anus, and rarely from peritoneal cavity or mesentery. GIST usually remain asymptomatic for a long time. Therefore 10 to 20% are found incidentally at endoscopy or at time of surgery for others reasons and metastases are found in 15 to 50% of cases at diagnonis. Histologicaly, they are characterized by a cellular proliferation constituted of either spindle or epithelioid cells. Diagnosis has to be confirmed by immunohistochemistry, with positivity of KIT in 95% of cases, or by molecular biology, with "gain of function" mutations of KIT or PDGFRA in 85% of cases. Primary localization, mitotic activity and tumor size are the main prognostic factors. Metastases occur in 30 to 50% of patients with GIST. GIST are highly resistant to conventional chemotherapy and results obtained with new targeted therapies like Imatinib constitute one of the major progress in oncology during the decade.

Expression de c-kit dans les carcinomes nasopharyngés nord africains, corrélations avec l'âge et LMP1

PURPOSE

To determine the level and prognostic significance of c-kit expression in the two age groups of North African nasopharyngeal carcinomas.

PATIENTS AND METHODS

A retrospective study of 99 NPC specimens from Tunisian patients was investigated by immunohistochemistry. Immunohistochemical data were correlated with Epstein-Barr virus LMP1 expression and pathological, clinical and survival parameters.

RESULTS

c-kit was detected in 79% of the cases for patients under 30 years of age (juvenile form) but in only 56% of specimens in patients over 30 years (P=0.039) and was significantly over-expressed for patients with lymph node involvement (P=0.015). LMP1 score was 5.78 (+/-1.84) for c-kit negative tumors compared to 8,23 (+/-2.39) for c-kit positive tumors (P=0.002). Multivariate analysis including age, lymph nodes involvement and LMP1 expression as co-variables, showed that only age (P=0.027) and LMP1 expression (P=0.005) were significantly correlated to the c-kit expression.

CONCLUSION

c-kit is highly expressed in the juvenile form of North African nasopharyngeal carcinomas. There is a significant association between LMP1 and c-kit expression. The contrasted levels of C-kit expression in the two age groups strengthen the hypothesis that these clinical forms result from distinct oncogenic mechanisms.