Familial multiple gastrointestinal stromal tumours with associated abnormalities of the myenteric plexus layer and skeinoid fibres

AIMS: Multiple familial gastrointestinal stromal tumours are rare. We report the third family with two cases of multiple gastrointestinal stromal tumours showing skeinoid fibres. Associated abnormalities of the myenteric plexus layer are described and new hypotheses for the histogenesis of gastrointestinal stromal tumours are formulated. METHODS AND RESULTS: Multiple gastrointestinal stromal tumours developed in the duodenum and proximal jejunum were removed from mother and son. No history of a specific syndrome or of mastocytosis was known. Light microscopy revealed typical gastrointestinal stromal tumours with skeinoid fibres. An unusual abnormality of the myenteric plexus layer, showing a diffuse spindle cell hyperplasia, was noted in the macroscopically normal digestive wall. No abnormalities of the ganglion cells were associated. Tumours and the spindle cell hyperplasia showed similar morphological and immunohistochemical features with expression of CD34 and CD117 antigens. Follow-up revealed recurrences in the mother. CONCLUSION: The morphological characteristics of these two cases of familial gastrointestinal stromal tumours and of the associated abnormalities of the myenteric plexus layer, help to better explain the histogenesis of multiple familial gastrointestinal stromal tumours. The hyperplasia of the myenteric plexus could be considered a risk factor for recurrent tumours.     

Prognostic significance of p53 gene mutations and protein overexpression in localized gastrointestinal stromal tumours

AIMS: Mutation of c-kit is a relatively early event in the tumorigenesis of gastrointestinal stromal tumours (GISTs). The aim was to determine the prognostic significance of p53 alterations as an additional genetic change in GISTs. METHODS AND RESULTS: We reviewed 125 patients with localized GISTs subjected to complete resection between 1990 and 2002. Mutational analyses of c-kit exons 9, 11, 13 and 17, p53 exons 4-8 and immunohistochemistry for p53 protein were conducted using paraffin-embedded tissues. Alterations of p53 were observed in 50 patients (40.0%). Based on the National Institutes of Health's risk category, p53 alterations were noted more frequently in the higher risk categories (P = 0.041). With a median follow-up of 56.5 months (range: 2.3-126.8), 5-year relapse-free survival (RFS) rates were 61.7% without p53 alterations, compared with only 40.2% with p53 alterations (P = 0.009). Multivariate analysis indicated that p53 alterations comprised an independent, poor prognostic factor for RFS, in addition to c-kit mutations, large size, a high mitotic count and non-gastric primary sites. CONCLUSIONS: Alterations in p53 were more commonly observed in localized GISTs at higher risk of relapse. This suggests that they are significant as an independent, poor prognostic factor.     

The expression of p53 and bcl-2 in gastrointestinal stromal tumours is associated with anatomical site, and p53 expression is associated with grade and clinical outcome

AIMS: To compare the expression of p53 and bcl-2 in gastrointestinal stromal tumours (GISTs) with anatomical site, National Institutes of Health (NIH) risk category (grade), pathological features, and clinical outcome. METHODS AND RESULTS: The immunohistochemical expression of p53 and bcl-2 in 105 GISTs (71 gastric, 20 small intestinal, four colonic, 10 rectal) was recorded. When all GISTs were assessed, there was p53 positivity in 28% and bcl-2 positivity in 77%. Gastric tumours had a lower prevalence of p53 positivity (20%) than intestinal (40-50%). Rectal GISTs had the lowest prevalence of bcl-2 positivity (20%) and gastric and small intestinal the highest (80% and 90%, respectively). In GISTs from all sites, p53 positivity was associated with size > 50 mm, epithelioid cell shape, nuclear atypia, mucosal invasion, and mitotic count > 5/50 high-power fields. In gastric GISTs the associations were the same, apart from size and mitotic count. In GISTs from all sites and in gastric GISTs, p53 expression correlated with NIH risk category. When GISTs from all sites were subjected to univariate survival analysis, an adverse outcome was associated with p53 positivity, NIH risk category, and several established prognostic factors. When gastric GISTs were assessed, the associations were similar although size was not prognostic. In multivariate survival analysis, p53 expression was independently prognostic for gastric GISTs in some models, while it was never independently prognostic for GISTs from all sites. Whether all GISTs or gastric GISTs were assessed, bcl-2 showed no association with clinical outcome or risk category. CONCLUSIONS: Anatomical site influences p53 and bcl-2 expression in GISTs. p53 expression is associated with NIH risk category, various pathological features, and clinical outcome, and may be independently prognostic for gastric GISTs. Bcl-2 expression has no prognostic value.     

胰腺癌中p-Akt、HSP90的表达及其临床意义

目的 探讨胰腺癌组织中p-Akt与HSP90蛋白的表达及其与胰腺癌临床病理参数和预后的相关性及意义.方法 应用高通量的组织芯片技术免疫组织化学方法检测88例无术前放化疗史的胰腺癌手术标本和11例非肿瘤性胰腺组织中p-Akt和HSP90蛋白的表达情况,运用Spearman秩相关分析两者之间的相关性,并对随访2个月～6年的53例病例作生存分析.结果 88例胰腺癌组织中,p-Akt、HSP90高表达率分别为46(52.3%)、65(73.9%).p-Akt、HSP90高表达和胰腺癌的临床TNM分期、淋巴结转移存在相关性(P<0.01),与肿瘤病理分级、部位和大小无关(P>0.05).经Spearman秩相关分析显示p-Akt、HSP90在胰腺癌中有协同表达(P<0.05).在有随访结果的53例病例中,单因素Cox分析显示,p-Akt表达均与胰腺癌预后有关(P<0.05).结论 p-Akt、HSP90的表达与胰腺癌临床病理参数相关,并且p-Akt表达可作为胰腺癌的预后指标.     

喉癌组织中MKRN1和HSP90基因表达的研究

【摘要】目的 正常细胞中MKRN1和HSP90基因的平衡决定了端粒酶活性和端粒长度,使细胞保持正常的状态。二者的表达异常可能与肿瘤的发生发展有关。为探讨MKRN1和HSP90基因的表达与喉癌发生发展之间的关系,我们研究了喉癌组织中MKRN1和HSP90基因mRNA的表达情况。方法 提取35例喉癌组织的总mRNA,用半定量RT-PCR的方法检测MKRN1和HSP90基因mRNA的表达情况。结果 35例喉鳞癌中有18例MKRN1基因mRNA表达下调,占51.4%（18/35）;16例HSP90基因mRNA表达上调,占45.7%（16/35）。 MKRN1基因在肿瘤组织中的表达水平为0.74±0.63,在癌旁正常对照组织中为1.21±0.76,（P＜0.01）。HSP90基因在肿瘤组织中表达水平为1.82±1.25,而在癌旁正常对照组织中为1.23±1.04,（P＜0.05）,统计学上具有显著差异。MKRN1与HSP90基因的表达存在负相关(r=-0.458, P＜0.05)。HSP90基因表达情况与肿瘤的病理分期和患者年龄相关 (P＜0.05) ,MKRN1的表达与肿瘤的临床特征均无相关性(P＞0.05)。结论 喉癌组织中MKRN1和HSP90基因mRNA的表达异常存在相关性,二者表达平衡的破坏可能在喉癌的发生发展中起着重要的作用。     

Site-independent prognostic value of chromosome 9q loss in primary gastrointestinal stromal tumours

Although the significance of tumour site for estimating malignant potential in gastrointestinal stromal tumours (GISTs) has recently been recognized, site-specific genetic patterns have not to date been defined. This study examined 52 c-kit-positive primary GISTs (with a mean follow-up of 42.3 months in 51 cases) from three different locations (35 gastric, 12 small intestinal, and five colorectal) using comparative genomic hybridization (CGH). In general, tumour site correlated with key prognostic factors, including tumour size, mitotic rate, proliferative activity, and probable malignant potential. Furthermore, several DNA copy number changes showed a site-dependent pattern. These included losses at 14q (gastric 83%, intestinal 35%; p = 0.001), losses at 22q (gastric 46%, intestinal 82%; p = 0.02), losses at 1p (gastric 23%, intestinal 88%; p = 1 x 10(-5)), losses at 15q (gastric 14%, intestinal 59%; p = 0.002), losses at 9q (gastric 14%, intestinal 53%; p = 0.006), and gains at 5p (gastric 11%, intestinal 53%; p = 0.002). These data demonstrate strong site-dependent genetic heterogeneity in GISTs that may form a basis for subclassification. Prognostic evaluation of DNA copy number changes identified losses at 9q as a site-independent prognostic marker associated with shorter disease-free survival (p = 0.03) and overall survival (p = 0.002). Furthermore, 9q loss also appeared to carry prognostic value in predicting overall survival for patients with advanced or progressive GISTs (p = 0.003).     

KIT immunohistochemistry and mutation status in gastrointestinal stromal tumours (GISTs) evaluated for treatment with imatinib

AIMS: With the availability of effective but expensive treatment in the form of imatinib, accurate diagnosis of gastrointestinal stromal tumour (GIST) is extremely important. The aims of this study were: to describe the clinicopathological, immunohistochemical and molecular features of cases referred to a cancer centre with a possible diagnosis of GIST; to identify pitfalls in the performance and interpretation of KIT immunohistochemistry; to define the role of KIT mutation testing in making a diagnosis of GIST. METHODS AND RESULTS: Morphological review, KIT immunohistochemistry and mutation testing were performed on all cases referred with a diagnosis of GIST or where the diagnosis was under serious consideration on the basis of KIT immunopositivity with a view to treating with imatinib. Thirty-seven cases met the inclusion criteria. Of these, 26 were classified as GIST and 11 as non-GIST. Most GISTs showed strong diffuse membranous, cytoplasmic or paranuclear KIT immunopositivity. Some non-GISTs demonstrated patchy cytoplasmic KIT immunopositivity related to the immunohistochemical protocol used in the external laboratory, which led to erroneous diagnoses of GIST in nine (24%) cases. KIT mutations involving exons 11 or 9 were identified in 22 (88%) GISTs tested and none of the non-GISTs. CONCLUSIONS: An accurate diagnosis of GIST can be made on clinicopathological and immunohistochemical criteria without the need for mutational analysis in most cases, provided proper attention is paid to the immunohistochemical protocol used and, most importantly, control material. False-positive diagnoses of GIST potentially leading to inappropriate treatment with imatinib are more common than missed diagnoses.     

KIT and PDGFRalpha mutational analyses of mixed cell-type gastrointestinal stromal tumours

AIMS: To determine whether the epithelioid and spindle components of a mixed cell-type gastrointestinal stromal tumour (GIST) show the same receptor tyrosine kinase mutation and, by inference, the same sensitivity to imatinib. METHODS AND RESULTS: Six mixed cell-type GISTs were identified from 108 gastric GISTs. Clinicopathological and immunohistochemical data of the six neoplasms were collated. For each neoplasm, DNA was extracted separately from the laser-microdissected epithelioid and spindle components and non-neoplastic tissue and sequenced for KIT and platelet-derived growth factor receptor (PDGFR)alpha mutations. The epithelioid component often showed less CD117 and/or CD34 immunoreactivity than the spindle component of the same mixed cell-type GIST. Four mixed cell-type GISTs showed somatic KIT mutations (deletions in exon 11 in three tumours and an insertion in exon 9 in one tumour) and one showed a somatic PDGFRalpha mutation (point mutation in exon 18); in each of the five cases, both epithelioid and spindle components showed identical mutations. CONCLUSIONS: The presence of the same receptor tyrosine kinase mutation in both components of a mixed cell-type GIST suggests that both components should be equally responsive to imatinib treatment, and that such mutation is an early key event in the pathogenesis of these neoplasms.     

小胃肠间质瘤的临床病理学特征

目的探讨小胃肠间质瘤(small gastrointestinal stromal tumors,sGIST)的临床病理学特征。方法回顾性分析21例sGIST的临床病理学及免疫表型特征,对比分析非sGIST,并进行随访。结果 21例sGIST中女性7例,男性14例,中位年龄63岁,直径0.5~1.5 cm,主要发生于胃,全部为梭形细胞型,其中9例同时伴有胃肠道恶性肿瘤。与非sGIST相比,sGIST很少出现肿瘤内出血、坏死、黏膜侵犯、溃疡及核分裂,复发风险明显低于非sGIST;免疫组化标记p53、Ki-67及肿瘤内微血管密度(microvascular density,MVD)明显低于非sGIST,差异有统计学意义(P0.05)。结论 sGIST可与胃肠道恶性肿瘤同时伴发,免疫组化标记p53、Ki-67及MVD均低于非sGIST,其预后较好。     

Knock-in murine models of familial gastrointestinal stromal tumours

In recent years, gastrointestinal stromal tumour (GIST) has emerged from a poorly understood group of mesenchymal tumours to a distinct pathological entity that has become a leading model for new therapies targeting kinases. GIST pathogenesis is driven by receptor tyrosine kinase-activating mutations most often in KIT or PDGFRA that may be sporadic or result in familial GIST syndromes. In a recent issue of The Journal of Pathology (J Pathol 2008;214:302-311), Nakai and colleagues report that mutation of the previously un-modelled tyrosine kinase II domain of KIT generates a spectrum of features very similar to that in two human GIST families. Knock-in mouse models of GIST may prove extremely useful in pre-clinical evaluation of kinase-targeted compounds and of the mechanism of drug resistance, but intriguingly it now seems clearer that the distribution of GIST in mouse models and humans is different.     

Gastrointestinal stromal tumours: an update

Recently, there has been intense interest in the study of gastrointestinal stromal tumour (GIST); one might call it a virtual GIST revolution. This is due largely to the realization that most GISTs express KIT and harbour activating c-KIT (KIT) or platelet-derived growth factor receptor-alpha (PDGFRA) receptor tyrosine kinase mutations that can be targeted by small molecule pharmacological inhibitors. Pathologists have benefited greatly from this revolution, mainly in the form of an improved ability to classify GISTs and, even more recently, in understanding the molecular underpinnings that underlie many fascinating clinical and pathological correlations. It is the purpose of this review to summarize recent developments in GIST classification and the molecular pathogenesis of GIST.     

Clinical significance of oncogenic KIT and PDGFRA mutations in gastrointestinal stromal tumours

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Despite clinicopathological differences, GISTs share oncogenic KIT or platelet-derived growth factor-alpha ( PDGFRA ) mutations. Imatinib, KIT and PDGFRA inhibitor, has been successfully used in the treatment of metastatic GISTs. There are primary KIT or PDGFRA mutations diagnosed before imatinib treatment, linked to GIST pathogenesis, and secondary mutations detected during treatment, causing drug resistance. KIT exon 11 mutations are the most common. Gastric GISTs with exon 11 deletions are more aggressive than those with substitutions. KIT exon 11 mutants respond well to imatinib. Less common KIT exon 9 Ala502_Tyr503dup mutants occur predominantly in intestinal GISTs and are less sensitive to imatinib. An Asp842Val substitution in exon 18 is the most common PDGFRA mutation. GISTs with such mutation are resistant to imatinib. PDGFRA mutations are associated with gastric GISTs, epithelioid morphology and a less malignant course of disease. GISTs in neurofibromatosis 1, Carney triad and paediatric tumours generally lack KIT and PDGFRA mutations. Secondary KIT mutations affect exons 13–17. GISTs with secondary mutations in exon 13 and 14 are sensitive to sunitinib, another tyrosine kinase inhibitor. KIT and PDGFRA genotyping is important for GIST diagnosis and assessment of sensitivity to tyrosine kinase inhibitors.     

Absence of c-kit gene mutations in gastrointestinal stromal tumours from neurofibromatosis type 1 patients

Most sporadic gastrointestinal stromal tumours (GISTs) have somatic c-kit gene mutations that are considered to be causal. Neurofibromatosis type 1 (NF1) is caused by mutations of the NF1 gene and NF1 patients have an increased risk of developing GISTs. Since most neoplasms are considered to develop as a result of the combination of several gene mutations, these findings suggest that GISTs from NF1 patients might have somatic c-kit gene mutations and that sporadic GISTs from non-NF1 patients might have somatic NF1 gene mutations. The present study analysed 29 GISTs from seven NF1 patients for c-kit gene mutations and ten sporadic GISTs from ten non-NF1 patients for NF1 mutations. Exons 9, 11, 13, and 17 of the c-kit gene were amplified and directly sequenced after the extraction of genomic DNA from wax-embedded tissues from 26 GISTs from five NF1 patients. The whole coding region of the c-kit cDNA and the whole coding region of the NF1 cDNA were amplified and directly sequenced after RNA extraction and cDNA synthesis in three fresh GIST tissues from two NF1 patients and ten fresh GIST tissues from ten non-NF1 patients. Of the ten sporadic GISTs, eight had heterozygous mutations at exon 11, and one at exon 9, of c-kit. Heterozygous NF1 gene mutations were detected in GISTs from the two NF1 patients from whom fresh tissues were available. None of the 29 GISTs derived from NF1 patients had detectable c-kit gene mutations and none of the ten GISTs derived from non-NF1 patients had detectable NF1 mutations. These results suggest that the pathogenesis of GISTs in NF1 patients is different from that in non-NF1 patients.     

Discovered on gastrointestinal stromal tumours 1 (DOG1) expression in non-gastrointestinal stromal tumour (GIST) neoplasms

Hemminger J & Iwenofu O H
(2012) Histopathology  61, 170–177 Discovered on gastrointestinal stromal tumours 1 (DOG1) expression in non‐gastrointestinal stromal tumour (GIST) neoplasms Aims: To further characterize discovered on GIST1 (DOG1) antibody clone K9 expression in a broad range of mesenchymal and epithelial tumours. Methods and results: Formalin‐fixed paraffin‐embedded sections of various tumours were stained with the anti‐DOG1 monoclonal antibody clone K9. The tumours (n = 187) included: gastrointestinal stromal tumours (GISTs) (n = 20); malignant melanoma (n = 19); schwannoma (n = 10); neurofibroma (n = 10); leiomyosarcoma (n = 10); low‐grade fibromyxoid sarcoma (n = 5); angiosarcoma, (n = 10); epithelioid sarcoma (n = 5); clear cell sarcoma (n = 3); synovial sarcoma (n = 10); malignant peripheral nerve sheath tumour (MPNST) (n = 12); alveolar soft part sarcoma (n = 3); chordoma (n = 5); pleomorphic undifferentiated sarcoma (n = 5); perineurioma (n = 4); granular cell tumour (n = 6); acinic cell carcinoma (n = 5); adenocarcinoma, lung (n = 5), colon (n = 10), endometrioid (n = 10), prostate (n = 10) and renal cell (n = 10). Nineteen of 20 GISTs expressed DOG‐1 and 12 of 20 were diffusely positive (≥95%) with moderate to strong intensity. There was focal, predominantly luminal staining of colorectal (three of 10), endometrioid (four of 10) and acinic cell carcinomas (four of five). One case each of spindle cell/desmoplastic melanoma (2+), schwannoma (trace) and MPNST (2+) showed DOG‐1 expression. Conclusions: Our study supports that DOG‐1 is a highly sensitive and specific marker for GISTs and also highlights hitherto unrecognized and unusual patterns of expression in non‐mesenchymal neoplasms.     

Recent developments in gastroesophageal mesenchymal tumours

The pathologist’s approach to gastroesophageal mesenchymal tumours has changed dramatically during the last 25 years. In particular, gastrointestinal stromal tumour (GIST) has evolved from a wastebasket mesenchymal tumour category to a precisely defined entity with an increasingly detailed genetic subclassification. This subclassification has brought gastrointestinal mesenchymal neoplasia into the realm of precision medicine, with specific treatments optimised for particular genetic subtypes. Molecular genetic data have also greatly improved our understanding of oesophageal mesenchymal tumours, including the discovery that so‐called ‘giant fibrovascular polyps’ in fact represent a clinically distinctive presentation of well‐differentiated liposarcoma. Here, we will focus on gastroesophageal mesenchymal tumours for which there have been recent developments in classification, molecular genetics or tumour biology: granular cell tumour, ‘giant fibrovascular polyp’/well‐differentiated liposarcoma, plexiform fibromyxoma, gastroblastoma and, of course, GIST.