Gastrointestinal stromal tumors, intramural leiomyomas, and leiomyosarcomas in the duodenum: a clinicopathologic, immunohistochemical, and molecular genetic study of 167 cases

NF1-associated gastrointestinal stromal tumors have unique clinical, phenotypic, and genotypic characteristics

Gastrointestinal stromal tumors (GIST) have been reported to occasionally occur in patients with neurofibromatosis type 1 (NF1). This study aims to describe the phenotypic and genotypic characteristics of GIST in NF1 patients and attempts to elucidate the relationship between them. We analyzed GIST arising in 15 NF1 patients (8 males and 7 females, 19-82 years of age). Eleven patients had multiple GISTs (3 to >100 tumors) ranging from 1 mm to 10 cm in size and predominantly involving the small intestine including the duodenum. Tumors were symptomatic in 8 patients and incidental findings in the remaining 7 patients. Microscopically, the tumors cells were typically spindled and the mitotic rate low; 9 patients had tumors classified as very low or low risk and 6 as intermediate risk GIST. Nine patients were treated surgically and none developed metastases or died of disease. Immunohistochemical stains for CD117 were strongly positive in 47 of 50 GIST; they also accentuated hyperplastic foci (diffuse and focal) of the interstitial cells of Cajal that were often associated with microscopic GIST in the surrounding intestinal muscle wall. No KIT or PDGFRA mutations were detected in 24 GIST from 12 patients using dHPLC analysis and DNA sequencing. We conclude that patients with NF1 have a high risk of developing GIST. NF1-associated GIST are also phenotypically and genotypically distinct from sporadic GIST, indicating that different pathogenetic mechanisms are involved in their evolution.

Differential expression of connexin 43 in gastrointestinal stromal tumours of gastric and small intestinal origin

Gastrointestinal stromal tumours (GISTs) are considered to originate from interstitial cells of Cajal (ICCs). ICCs are classified into several subtypes according to their location or roles. Several reports indicate that GISTs of the small intestine appear to have different clinical and pathological characteristics from gastric GISTs. We previously found using a cDNA expression chip that connexin 43, a component of gap junctions, is expressed specifically in small intestinal GISTs but not in gastric GISTs. To confirm the specificity of connexin 43 expression, we analysed 10 small intestinal GISTs and 15 gastric GISTs by northern blotting, western blotting and immunohistochemistry in this study. Northern blotting was performed in five small intestinal GISTs and five gastric GISTs, and revealed connexin 43 mRNA expression in all of the five small intestinal GISTs, but in none of the gastric GISTs. By western blotting, bands corresponding to connexin 43 were easily detected in all of the five small intestinal GISTs studied but were absent in all five gastric GISTs analysed. Immunohistochemistry showed that all of the 10 small intestinal GISTs were positive for connexin 43 but only one of 15 gastric GISTs, which exhibited a mutation in exon 9 of the KIT gene, was connexin 43-positive. We also examined the localization of connexin 43 in the normal stomach and small intestine. Immunoreactivity for connexin 43 was present in both normal gastric and small intestinal circular muscle layers, but it was unclear which cell type was positive. These results suggest that GISTs are divided into at least two groups, namely the gastric subtype and the small intestinal subtype, through phenotype but not location. Furthermore, these data indicate that the gastric and the small intestinal subtypes of GIST may originate from different subtypes of ICC.

Gastrointestinal stromal tumors of neurofibromatosis type I (von Recklinghausen's disease)

Gastrointestinal stromal tumor (GIST), as well as the hyperplastic lesions of intestinal neural tissue and its supporting structures, is a gastrointestinal complication of type 1 neurofibromatosis (NF1) (von Recklinghausen's disease). In the present study, we analyzed the histologic and immunohistochemical features, and the c-kit and PDGFRA gene mutations of 36 GISTs derived from 9 NF1 patients. Distinctively, multiple GISTs arose preferentially in the small intestine. The histologic features of NF1-associated GISTs are almost similar to those of non-NF1 GISTs, but characteristically most of the NF1-associated GISTs contained skeinoid fibers. Thirty-three GISTs (92%) showed immunoreactivity for KIT, and 23 tumors (64%) showed diffuse or mosaic-like immunoreactivity for S-100 protein. Hyperplasic lesions, which may be the hyperplasia of interstitial cells of Cajal, were observed around some GISTs. Exons 9, 11, 13, and 17 of the c-kit gene and exons 12 and 18 of the PDGFRA gene were amplified and directly sequenced. Point mutations of c-kit gene or PDGFRA gene were identified only in three (8%) and two (6%) tumors, respectively. NF1-associated GISTs, showing the dual differentiation of interstitial cells of Cajal and Schwann cells, develop in close association with the myenteric nerve structure of gastrointestinal tract of NF1 patients. The point mutations of c-kit and PDGFRA gene may play a limited role in the tumorigenesis of NF1-associated GISTs.

A recurrent duodenal gastrointestinal stromal tumor with a frameshift mutation resulting in a stop codon in KIT exon 13

Gastrointestinal stromal tumors (GISTs) are a specific and rare subset of human gastrointestinal tract tumors. Most GISTs show gain-of-function mutations of KIT, mainly in exon 11, that always maintain the reading frame. We report on data from a 43-year-old Japanese man with recurrent duodenal GIST and a frameshift mutation in KIT exon 13 together with an in-frame deletion in KIT exon 11 detected by genomic DNA sequencing. Deletion of 48 base pairs of KIT exon 11, which preserved the reading frame, was identified in both primary and recurrent tumors, whereas deletion of one nucleotide of codon 642 of KIT exon 13, which changed the reading frame and induced a novel stop codon at amino acid 644, was found only in the recurrent tumor. The predicted protein resulting from the latter would lack part of the kinase domain. To the best of our knowledge, this is the first documentation of a GIST with a frameshift mutation of KIT.

PKC theta, a novel immunohistochemical marker for gastrointestinal stromal tumors (GIST), especially useful for identifying KIT-negative tumors

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor in the digestive tract and the majority of GIST has characteristic gain-of-function mutations of the c-kit gene, which encodes the KIT receptor for stem cell factor. The present study aimed to establish the usefulness of protein kinase C theta (PKC theta) as an immunohistochemical marker for GIST in comparison with KIT immunohistochemistry. PKC theta immunohistochemistry was carried out not only on 48 cases of GIST and another 40 cases of gastrointestinal mesenchymal tumors, but also on 24 cases of various tumors known to be immunohistochemically positive for KIT. Immunohistochemically, 41 out of 48 cases (85%) of GIST were positive for PKC theta, and its expression was confirmed by Western blot analysis using six cases of surgically resected GIST. In the present study there were six GIST immunohistochemically negative for KIT, which histologically revealed a myxoid epithelioid appearance characteristic to that of GIST with platelet-derived growth factor receptor alpha mutation. All six GIST were immunohistochemically positive for PKC theta. No PKC theta immunoreactivity was observed in other gastrointestinal mesenchymal tumors and various KIT-positive tumors except for three cases (14%) of gastrointestinal schwannomas. The present study revealed that PKC theta is an immunohistochemically novel and useful marker for GIST, especially for GIST negative for KIT.

Gastrointestinal stromal tumours (GISTs): a clinicopathological and molecular study of 66 cases

AIMS

Predicting the clinical behaviour of gastrointestinal stromal tumours (GISTs) is difficult and criteria delineating benign from malignant cases are not firmly established. The aims of this study were to define the clinicopathological and molecular features of 66 GISTs, and to determine whether any specific parameters were associated with patient outcome.

METHODS

Archival cases of GIST from two major teaching hospitals in Western Australia were studied. Inclusion criteria for the study were: (1) appropriate morphology, (2) CD117 positivity, (3) adequacy of pathological material for study, and (4) exclusion of other tumour types on the basis of immunophenotypic and/or ultrastructural features. Expression of CD117, CD34, S100 protein, keratin (using broad spectrum MNF116), alpha-smooth muscle actin (SMA) was determined by immunohistochemistry. PCR and single strand conformation polymorphism (PCR-SSCP) analysis were used to screen for mutations in exons 11 and 9 of c-kit.

RESULTS

There were equal numbers of males and females with a mean age at diagnosis of 60 years, followed up for a mean of 54 months. Thirteen patients (21%) had died of GIST by the end of the study. Tumours were mostly located in the stomach (67%) and small intestine (SI; 25%). The cell types were pure spindle (68%), pure epithelioid (12%) and mixed epithelioid/spindle (20%). c-kit mutations were found in 69% of GISTs, with the large majority (91%) occurring in exon 11. Size > or = 10 cm, tumour necrosis and pure epithelioid cell morphology each were the only factors significantly associated with adverse survival (p=0.038, and p=0.047 and p=0.028, respectively). Mitotic activity > or = 5/50 HPF showed a definite trend association with adverse survival, but unlike some other studies, did not achieve statistical significance (p=0.067). c-kit mutations were more frequent in small intestinal GISTs (p=0.05) and in those with pure spindle cell morphology (p=0.023) but were not associated with patient outcome.

CONCLUSION

In this study, size > or = 10cm, necrosis and/or pure epithelioid cell morphology correlated significantly with adverse survival. Mitotic activity showed a strong association with survival but this did not reach statistical significance. c-kit mutations occurred mainly in GISTs of the SI, and in purely spindle cell tumours. While the mutation status did not associate with patient outcome in this series, this remains a controversial issue, and further studies are needed to assess whether the type of mutation affects response to tyrosine kinase inhibitor therapy in metastatic GISTs. CD117 staining of any mesenchymal lesion of the gastrointestinal tract should be mandatory for accurate classification. PCR-SSCP analysis is a fast, sensitive and relatively inexpensive method of analysing c-kit mutations, which may be important prognostically and also of therapeutic relevance in the assessment of new tyrosine kinase inhibitor therapies.

In vivoTarget Modulation and Biological Activity of CHIR-258, a Multitargeted Growth Factor Receptor Kinase Inhibitor, in Colon Cancer Models

PURPOSE

To evaluate the therapeutic and biological effects of CHIR-258, an orally bioavailable, potent inhibitor of class III-V receptor tyrosine kinases, in colon cancer models.

EXPERIMENTAL DESIGN

The pharmacologic activity of CHIR-258 was characterized by monitoring target modulation as well as by evaluating the antitumor and antiangiogenic effects in human colon xenograft models.

RESULTS

CHIR-258 inhibits vascular endothelial growth factor receptor 1/2, fibroblast growth factor receptor 1/3, and platelet-derived growth factor receptor beta (PDGFRbeta) and shows both antitumor and antiangiogenic activities in vivo. Treatment of KM12L4a human colon cancer cells with CHIR-258 resulted in a dose-dependent inhibition of vascular endothelial growth factor receptor 1 and PDGFRbeta phosphorylation and reduction of phosphorylated extracellular signal-regulated kinase (ERK) levels, indicating modulation of target receptors and downstream signaling. In vivo administration of CHIR-258 resulted in significant tumor growth inhibition and tumor regressions, including large, established tumors (500-1,000 mm(3)). Immunohistochemical analysis showed a reduction of phosphorylated PDGFRbeta and phosphorylated ERK in tumor cells after oral dosing with CHIR-258 compared with control tumors. These changes were accompanied by decreased tumor cell proliferation rate and reduced intratumoral microvessel density. CHIR-258 inhibited the phosphorylation of PDGFRbeta and ERK phosphorylation in tumors within 2 hours following dosing and the inhibitory activity was sustained for >24 hours. Significant antitumor activity was observed with intermittent dosing schedules, indicating a sustained biological activity.

CONCLUSION

These studies provide evidence that biological activity of CHIR-258 in tumors correlates with efficacy and aids in the identification of potential biomarkers of this multitargeted receptor tyrosine kinase inhibitor. CHIR-258 exhibits properties that make it a promising candidate for clinical development in a variety of solid and hematologic malignancies.

Multiple gastrointestinal stromal tumors in type I neurofibromatosis: a pathologic and molecular study

Multiple gastrointestinal stromal tumors typically occur in familial form associated with KIT receptor tyrosine kinase or platelet-derived growth factor receptor-alpha (PDGFRA) germline mutations, but may also develop in the setting of type 1 neurofibromatosis. The molecular abnormalities of gastrointestinal stromal tumors arising in neurofibromatosis have not been extensively studied. We identified three patients with type 1 neuro-fibromatosis and multiple small intestinal stromal tumors. Immunostains for CD117, CD34, desmin, actins, S-100 protein, and keratins were performed on all of the tumors. DNA was extracted from representative paraffin blocks from separate tumor nodules in each case and subjected to a nested polymerase chain reaction, using primers for KIT exons 9, 11, 13, and 17 and PDGFRA exons 12 and 18, followed by direct sequencing. The mean patient age was 56 years (range: 37-86 years, male/female ratio: 2/1). One patient had three tumors, one had five, and one had greater than 10 tumor nodules, all of which demonstrated histologic features characteristic of gastrointestinal stromal tumors and stained strongly for CD117 and CD34. One patient died of disease at 35 months, one was disease free at 12 months and one was lost to follow-up. DNA extracts from 10 gastrointestinal stromal tumors (three from each of two patients and four from one patient) were subjected to polymerase chain reactions and assessed for mutations. All of the tumors were wild type for KIT exons 9, 13, and 17 and PDGFRA exons 12 and 18. Three tumors from one patient had identical point mutations in KIT exon 11, whereas the other tumors were wild type at this locus. We conclude that, although most patients with type 1 neurofibromatosis and gastrointestinal stromal tumors do not have KIT or PDGFRA mutations, KIT germline mutations might be implicated in the pathogenesis of gastrointestinal stromal tumors in some patients.

Gastrointestinal stromal tumors: a clinicopathologic and immunohistochemical study of 136 cases

The clinicopathologic features of 136 gastrointestinal stromal tumors were analyzed. The tumors occurred in 60 women and 76 men, ranging in age from 19 to 88 years (median 59 years, mean 59.2 years). Sixty-one cases arose from stomach, 38 from small intestine and 11 from colon or rectum. Abdominal cavity was indicated as tumor site in 10 cases, but the extra-gastrointestinal origin using strict criteria was not proved. Four locally recurrent cases and 12 metastatic samples were also included. The primary and recurrent tumors ranged in size from 0.5 to 30 cm (mean 8.3 cm). The large number of high-grade cases (85 of 112 classifiable) is alarming and emphasize the importance of oncology care. Histologically, ninety-two cases were classified as spindle cell while 11 as epithelioid GIST. Mixed cellularity was seen in 33 cases. Skeinoid fibers were present in 14 and coagulation necrosis in 40 primary cases. Ulceration observed by microscopic examination was common (36 of 110 cases, 32.7%), explaining the clinically frequently observed gastrointestinal bleeding. Unusual histological features such as stromal hyalinization and nuclear palisading were present in 30 and 27 cases, respectively. Immunohistochemical CD117 (c-kit) positivity was documented in 133 cases. Three cases with CD117 negative results were included, because their morphology was most consistent with GIST and immunohistochemical reactions excluded the possibility of other neoplasms. CD34 positivity was seen in 70%, alpha-smooth muscle actin positivity in 39.6% of examined cases. Only one case showed desmin reactivity and seven had S100 positive tumor cells. For h-caldesmon 39 cases proved to be positive (60.9% of the tested cases).

Gastrointestinal stromal tumors in patients with neurofibromatosis: imaging features with clinicopathologic correlation

OBJECTIVE

The purpose of this study was to evaluate the clinical, pathologic, and imaging features of gastrointestinal stromal tumors that occur in patients with neurofibromatosis.

CONCLUSION

Gastrointestinal stromal tumors that occur in patients with neurofibromatosis commonly originate from the proximal small intestine and are often multiple. The cross-sectional imaging appearance of gastrointestinal stromal tumors that occur in patients with neurofibromatosis is similar to that of gastrointestinal stromal tumors that occur in the general population.

Analysis of CD117-negative gastrointestinal stromal tumors

AIM: To identify the gastrointestinal stromal tumors (GISTs) that are negative for CD117 expression by immunohistochemistry and to characterize their malignant potential.

METHODS: A total of 108 primary mesenchymal tumors of the gastrointestinal tract were screened to select CD117-negative tumors, from which KIT (exons 9, 11, 13, and 17) and PDGFRA (exons 10, 12, 14, and 18) were sequenced to identify GISTs. Tumor recurrence and distant metastasis were used as the criteria of malignancy.

RESULTS: The result showed that approximately 25% (29/108) of the gastrointestinal mesenchymal tumors were negative for CD117 and approximately 6% (7/108) of the tumors were CD117-negative GISTs. All these CD117-negative tumors had a mutated KIT and a wild-type PDGFRA. All CD117-negative GISTs with mutations at codons 557/558 of KIT had mitotic counts >10/50 high power field, and 75% (3/4) of them showed multiple recurrence or distant metastasis.

CONCLUSION: CD117-negative KIT mutated GISTs account for approximately 6% of the gastrointestinal mesenchymal tumors. Tumor recurrence or distant metastasis correlates to both the KIT mutations at codons 557/558 and the mitotic counts, but not to the tumor size.

Gastrointestinal stromal tumors of the stomach: a clinicopathologic, immunohistochemical, and molecular genetic study of 1765 cases with long-term follow-up

Gastrointestinal (GI) stromal tumors (GISTs), the specific KIT- or PDFGRA-signaling driven mesenchymal tumors, are the most common mesenchymal tumors of the GI tract. In this study, we analyzed 1869 cases originally classified as smooth muscle tumors of the stomach and found that 1765 (94%) of these were GISTs. The GISTs had a slight male predominance (55%) with a median age of 63 years. Only 2.7% of tumors occurred before the age of 21 years and 9.1% before the age of 40 years. The tumors varied from 0.5 to 44 cm (median, 6.0 cm) and most commonly presented with GI bleeding; 12% were incidentally detected. Several histologic variants were recognized among the spindle cell tumors (sclerosing, palisaded-vacuolated, hypercellular, and sarcomatous) and of epithelioid tumors (sclerosing, dyscohesive, hypercellular, and sarcomatous). Outcome was strongly dependent on tumor size and mitotic activity. Only 2% to 3% of tumors <10 cm and <5 mitoses/50 HPFs metastasized, whereas 86% of tumors >10 cm and >5 mitoses/50 HPFs metastasized. However, tumors >10 cm with mitotic activity <5/50 HPFs and those <5 cm with mitoses >5/50 HPFs had a relatively low metastatic rate (11% and 15%). A small number of patients survived intra-abdominal metastasis up to over 20 years. Tumor location in fundus or gastroesophageal junction, coagulative necrosis, ulceration, and mucosal invasion were unfavorable factors (P <0.001), whereas tumor location in antrum was favorable (P <0.001). KIT expression was detected in 91% of the cases, CD34 in 82%, smooth muscle actin in 18%, and desmin in 5%; the latter two were favorable (P <0.001). KIT exon 11 mutations were detected in 119 cases; patients with point mutations fared better than those with deletions (P <0.01). PDGFRA exon 18 mutations (total 86 cases) were common in epithelioid GISTs and most commonly represented a D842V point mutation; none of these was prognostically significant. The above results may be helpful for setting the criteria for adjuvant treatment such as Gleevec.

Loss of heterozygosity on chromosome 22q in gastrointestinal stromal tumors (GISTs): a study on 50 cases

Mutational activation of KIT or PDGFRA is considered an early step in pathogenesis of gastrointestinal stromal tumors (GISTs); however, other nonrandom genetic changes have also been identified. At least three common regions of deletions on chromosome 22q, which may harbor putative tumor suppressor genes, have been defined. However, mapping of these regions has been inconsistent. It has also been speculated that GI autonomous nerve tumors (GANTs), GISTs with ultrastructural features suggestive of autonomic nerve differentiation, are characterized by a specific deletion involving 22q13 cytogenetic region. This study was undertaken to evaluate loss of heterozygosity (LOH) on chromosome 22q in 50 GISTs, including 10 GANTs. Four tumors were incidental minimal lesions <or=10 mm in diameter. LOH was evaluated using 20 PCR-based microsatellite markers and capillary gel electrophoresis. In all, 15 (30%) cases showed LOH of more than 75% of informative markers, suggesting loss of chromosome 22q. A total of 24 GISTs (50%) revealed LOH of one to seven informative markers clustered in different loci suggesting simultaneous involvement of different regions. The highest frequency of LOH was seen at D22S922 and D22S425, mapped to 22q13.33 and 22q11.22, respectively. However, LOH at other regions including IL2RB and NF2 locus was also found. No NF2 mutations were identified in four analyzed tumors. LOH on chromosome 22q was more frequent among intestinal than among gastric GISTs; however, there was no difference between LOH pattern seen in tumors defined by different histologic, ultrastructural (GANT) and molecular features (KIT and PDGFRA mutations). Although minimal GISTs revealed LOH on chromosome 22q, there was a higher LOH frequency in malignant than in benign tumors. An isolated LOH at D22S425 was equally found in both benign and malignant tumors. These observations may suggest that LOHs on chromosome 22q in GISTs play a role in early stages of tumor formation as well as in late tumor progression.

The epidemiology of malignant gastrointestinal stromal tumors: an analysis of 1,458 cases from 1992 to 2000

OBJECTIVES

The epidemiology of gastrointestinal stromal tumor has not been well examined, and prior studies often provide conflicting results. We conducted the first population-based study to evaluate the incidence and survival of malignant gastrointestinal stromal tumor in the United States.

METHODS

We utilized the Surveillance, Epidemiology, and End Results registry from the National Cancer Institute to identify all cases of malignant gastrointestinal stromal tumor diagnosed from 1992 to 2000. The age-adjusted incidence rates and the survival rates were calculated. Cox proportional hazards models were used to examine the risk of mortality.

RESULTS

Between 1992 and 2000, there were 1,458 cases of diagnosed gastrointestinal stromal tumor. The age-adjusted yearly incidence rate was 0.68/100,000. The mean age at diagnosis was 63 yr. Fifty-four percent were men and 46% were women. The incidence rate was higher among men and among Blacks. Fifty-one percent of cases were in the stomach, 36% small intestine, 7% colon, 5% rectum, and 1% in the esophagus. Fifty-three percent of cases were staged as localized, 19% regional, 23% distant, and 5% unstaged. The 1- and 5-yr relative survival rates were 80% and 45%, respectively. The Cox analysis showed that older age, Black race, advanced stage, and receipt of therapy were independent predictors of mortality.

CONCLUSIONS

Malignant gastrointestinal stromal tumors rare, but are more common in the older population, men, and Blacks. Risk factors for mortality include older age, Black race, advanced stage, and no surgical intervention.

Gastric GI stromal tumors (GISTs): The role of surgery in the era of targeted therapy

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasm arising in the stomach. These tumors were previously classified as smooth muscle tumors, but in recent years it has become clear that they are clinically, pathologically, and molecularly distinct from other tumors and are much more common than previously appreciated. Historically, patients with primary localized or advanced GIST have been managed surgically, as there was no proven role of other treatment modalities such as radiation or chemotherapy. However, the field of GIST was revolutionized with the 1998 discovery that the vast majority of these tumors have oncogenic gain-of-function mutations of the KIT receptor tyrosine kinase. Follow-up studies have confirmed that KIT is both a useful diagnostic marker and an excellent therapeutic target. Imatinib, an inhibitor of KIT kinase activity, is now the standard front-line therapy for patients with advanced GIST. In this review, we discuss pathological and molecular features of gastric GISTs and review the historic and current roles of surgery in the treatment of patients with primary or metastatic GIST. The importance of a multi-disciplinary approach using both surgery and imatinib therapy is emphasized.

Gastrointestinal stromal tumor of the stomach with rhabdoid phenotype: immunohistochemical, ultrastructural, and immunoelectron microscopic evaluation

A variety of neoplasms with rhabdoid differentiation have been reported in many sites. The authors describe a case of gastrointestinal stromal tumor (GIST) of the stomach that exhibited prominent rhabdoid features. Immunohistochemically, the tumor cells displayed positive staining for vimentin, c-kit, CD34, and alpha smooth muscle actin. Ultrastructural examination of the rhabdoid tumor cells revealed paranuclear whorls of intermediate filaments, which were immunoreactive for vimentin by both light microscopic immunohistochemical and protein A gold immunoelectron microscopic techniques. On H&E light microscopic examination alone, such a tumor could be mistaken for a variety of epithelial, mesenchymal, or other neoplasms that may show rhabdoid features. One report of GIST with a rhabdoid histologic phenotype has been described. This is the second known report of such a case with immunophenotypic and ultrastructural evaluation, and the first case with immunoelectron microscopic examination.

Tumeur stromale gastro-intestinale chez l’enfant

Stromal gastrointestinal tumors or GIST are undifferentiated mesenchymal tumors of gastrointestinal tract that showed characteristic c-kit expression. GIST are very rare in children and only 21 cases are reported in literature. The authors present a GIST arising in the stomach of a 7-year-old girl and revealed by severe anaemia. The patient underwent surgical resection and chemotherapy because of high-risk markers. Positive diagnosis and prognosis of paediatric GIST are discussed with literature data.

Gastrointestinal stromal tumor presenting as a scrotal mass

We describe a huge abdominal gastrointestinal stromal tumor (GIST) extending through the right inguinal canal. The reported case illustrates that the scrotum might be a place of initial presentation of a GIST growing along preformed anatomical structures. Urologists should be aware of this condition that might be mistaken for a primarily testicular malignancy.

Biology of gastrointestinal stromal tumors

Once a poorly defined pathologic oddity, in recent years, gastrointestinal stromal tumor (GIST) has emerged as a distinct oncogenetic entity that is now center stage in clinical trials of kinase-targeted therapies. This review charts the rapid progress that has established GIST as a model for understanding the role of oncogenic kinase mutations in human tumorigenesis. Approximately 80% to 85% of GISTs harbor activating mutations of the KIT tyrosine kinase. In a series of 322 GISTs (including 140 previously published cases) studied by the authors in detail, mutations in the KIT gene occurred with decreasing frequency in exons 11 (66.1%), 9 (13%), 13 (1.2%), and 17 (0.6%). In the same series, a subset of tumors had mutations in the KIT-related kinase gene PDGF receptor alpha (PDGFRA), which occurred in either exon 18 (5.6%) or 12 (1.5%). The remainder of GISTs (12%) were wild type for both KIT and PDGFRA. Comparative studies of KIT-mutant, PDGFRA-mutant, and wild-type GISTs indicate that there are many similarities between these groups of tumors but also important differences. In particular, the responsiveness of GISTs to treatment with the kinase inhibitor imatinib varies substantially depending on the exonic location of the KIT or PDGFRA mutation. Given these differences, which have implications both for the diagnosis and treatment of GISTs, we propose a molecular-based classification of GIST. Recent studies of familial GIST, pediatric GIST, and variant forms of GIST related to Carney's triad and neurofibromatosis type 1 are discussed in relationship to this molecular classification. In addition, the role of mutation screening in KIT and PDGFRA as a diagnostic and prognostic aid is emphasized in this review.

[Malignant gastrointestinal stromal tumor (GIST) of the papilla vateri. A rare tumor entity]

We present the case report of a 68-year-old female patient who had a malignant gastrointestinal stromal tumor of the papilla of Vater. The abdominal CT showed a coin-shaped lesion in the liver (segment VIII). Intraoperative rapid histological examination detected an old parasitic hepatic cyst. To exclude metastasis, we performed duodenopancreatectomy with curative intention. The postoperative course was without complications and neither chemotherapy nor other adjunct treatment was necessary. Because of heterogeneity, the different localization, and in this case the rare localization, surgery of gastrointestinal stromal tumors is difficult. However, we adhered to oncological and therapeutic standards of surgery for papillary carcinoma. This case is discussed based on a review of the literature. However, until now there has been no case report of gastrointestinal stromal tumor of the papilla of Vater in the literature.

Differential diagnosis of gastrointestinal stromal tumor and other spindle cell tumors in the gastrointestinal tract based on immunohistochemical analysis

To confirm the usefulness of an immunohistochemical panel of antibodies for KIT (c-kit/CD117), CD34, desmin, smooth-muscle actin (SMA), h-caldesmon (HCD), S-100 protein, neuron-specific enolase (NSE), and beta-catenin, 297 mesenchymal and peripheral nerve-sheath tumors of the gastrointestinal tract and intra-abdominal locations including 211 gastrointestinal stromal tumors (GISTs), 12 leiomyomas, 18 leiomyosarcomas, 17 solitary fibrous tumors (SFTs), 14 schwannomas, and 25 desmoid-type fibromatoses (DTFs) were analyzed immunohistochemically. Consistent (100%) immunoreactivity for KIT, CD34, desmin and S-100, and nuclear accumulation of beta-catenin were detected in GISTs, SFTs, smooth-muscle tumors, schwannomas, and DTFs, respectively. Immunoreactivity for SMA, HCD, and NSE was observed in a wide range of these tumors. In addition, 418 bone and soft tissue tumors were enrolled in this study for KIT immunostaining. As a result, a limited number of these tumors were KIT positive, including synovial sarcoma that showed morphological similarity to GISTs. These findings suggest that KIT, CD34, desmin, S-100, and beta-catenin are key markers for clinical diagnosis of GISTs and other spindle cell tumors that may involve the gastrointestinal tract, whereas SMA, HCD, and NSE have only limited value.

Endoscopic ultrasonography follow-up in patients with upper gastrointestinal submucosal tumours

AIM: To observe the alteration of upper gastrointestinal submucosal tumor (SMT).

METHODS: The first diagnostic SMT patients (n = 32) were observed with endoscopic ultrasonography (EUS) and followed-up.

RESULTS: The second and the first EUS findings coincided in 90.1% of cases (29/32), 95.5% (21/22) of the SCT diagnoses were identical to the first EUS. In 21 SCT cases, which diagnosed with EUS in both times, 33.3% showed the alteration of growth type in the second time, and 47.6% showed difference between both EUS-examinations; 57.1% (12/21) of the double EUS showed different tumor size, 66.7% (8/12) of which ones were greater than the first EUS. The diameter was increased 3.5 (2-7) mm in a 9-month follow-up term.

CONCLUSION: EUS is very accurate for the diagnosis of upper gastrointestinal SMT, and long time follow-up with EUS is necessary to distinguish the benign from malignancy of SMT and to guide the therapeutic approach.

KIT 1530ins6 mutation defines a subset of predominantly malignant gastrointestinal stromal tumors of intestinal origin

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. GISTs express KIT and show gain-of-function KIT mutations. Most of these mutations affect the KIT juxtamembrane domain, but other KIT domains are mutated at a lower frequency. In this study, frequency of GCC TAT insertion mutation (1530ins6) in KIT exon 9 (extracellular domain) and its possible clinicopathologic significance was investigated. Screening of 520 GISTs identified 26 cases with 1530ins6 KIT mutation and confirmed the previously reported low frequency of this type of KIT mutation among GISTs of different locations. Of the 26 tumors with 1530ins6 KIT mutation studied, 21 originated from the small intestine, 1 from the colon, and 3 from the rectum. In 1 case, primary small intestinal versus colonic localization could not be clearly established because of intra-abdominal dissemination. No distinctive morphological features were identified for the cohort of tumors defined by 1530ins6 KIT mutations. Most of the tumors showed predominant spindle cell morphology, and a few cases had epithelioid or pleomorphic histological features. Following previously published criteria based on tumor size and mitotic rate, 22 of 26 (85%) tumors were classified as malignant or potentially malignant, and 4 (15%) were classified as probably benign. A malignant clinical course was documented in 18 of 19 tumors from the malignant category. The survival times of 11 patients who died of disseminated GISTs ranged from 1 month to 105 months (median survival time, 26 months). In contrast, 2 of 4 GISTs assigned as probably benign tumors with follow-up information had long disease-free survival. GISTs carrying 1530ins6 occur exclusively in the intestinal location, and a great majority of these tumors follow a malignant course.

Primary malignant gastrointestinal stromal tumor of the liver

We report the case of a malignant, primary, hepatic gastrointestinal stromal tumor (GIST) that was resected from the liver of a 79-year-old woman. To our knowledge, this is the first primary, hepatic GIST on record. The tumor expressed CD117 (c-Kit protein) and vimentin and had the ultrastructural features of GISTs. Sixteen months after partial hepatectomy and resection of the tumor, a hilar lymph node metastasis was found. The metastatic tumor had the same morphologic features as the primary tumor, but in addition it contained numerous multinucleated giant cells. This case shows that GIST can occur as a primary liver tumor, and accordingly, we point out that not all hepatic tumors with a GIST phenotype should be automatically considered to be metastases from a primary gastrointestinal site.