c-kit immunocytochemical staining in the cytologic diagnosis of metastatic gastrointestinal stromal tumor. A report of two cases

BACKGROUND: Gastrointestinal stromal tumor (GIST) is a distinct group of mesenchymal neoplasms recently shown to exhibit differentiation toward interstitial cells of Cajal (ICC). C-kit (CD117), an immunocytochemical marker consistently expressed in normal ICC, is demonstrable in 81-100% of GISTs. We report two cases wherein immunocytochemical staining for c-kit aided in the diagnosis of metastatic GIST in the liver. CASES: Two patients, a 37-year-old female (case 1) and a 76-year-old male (case 2), presented with multiple nodules in the liver. They had a history of small bowel GIST resected 11 and 1 year earlier, respectively. Fine needle aspiration of the liver nodules showed loose aggregates or fascicles of spindle cells with elongated to oval nuclei, rare paranuclear vacuoles and eosinophilic cytoplasm. The spindle cells showed minimal (case 1) to moderate nuclear pleomorphism (case 2), with occasional mitotic figures seen in case 2. Immunocytochemical staining revealed strong and diffuse staining for c-kit; it was negative for actin, desmin, CD34 and S-100 protein. Thus, a diagnosis of metastatic GIST was rendered. Histologic review of the primary small bowel GISTs of both cases and the subsequently resected liver nodules in case 1 confirmed the diagnosis. CONCLUSION: Metastatic GIST may pose diagnostic problems due to its broad morphologic spectrum and variable cytologic atypia; in particular, distinction from leiomyosarcoma and other mesenchymal tumors is difficult. The diagnostic difficulty is compounded when the prior history of gastrointestinal tumor is not available or forgotten and when GIST is the initial presentation of the tumor. C-kit is a highly sensitive and reliable immunocytochemical marker that can aid in the diagnosis.     

Gain-of-Function Mutations of Receptor Tyrosine Kinases in Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in human gastrointestinal tract. We first found that most GISTs expressed KIT, a receptor tyrosine kinase encoded by protooncogene c-kit and that approximately 90% of the sporadic GISTs had somatic gain-of-function mutations of the c-kit gene. Since both GISTs and interstitial cells of Cajal (ICCs) were double-positive for KIT and CD34, GISTs were considered to originate from ICCs or their precursor cells. We also found that germline gain-of-function mutations of the c-kit gene resulted in familial and multiple GISTs with diffuse hyperplasia of ICCs as the preexisting lesion. Moreover, we found that about half of the sporadic GISTs without c-kit gene mutations had gain-of-function mutations of platelet-derived growth factor receptor alpha (PDGFRA) gene that encodes another receptor tyrosine kinase. Imatinib which is known to inhibit constitutively activated BCR-ABL tyrosine kinase in chronic myelogenous leukemia also inhibits constitutive activation of mutated KIT and PDGFRA, and is now being used for metastatic or unresectable GISTs as a molecular target drug. Mutational analyses of c-kit and PDGFRA genes are considered to be significant for prediction of effectiveness of imatinib and newly developed/developing other agents on GISTs. Some mouse models of familial and multiple GISTs have been genetically created, and may be useful for further investigation of GIST biology.     

Giant gastrointestinal stromal tumor with predominantly cystic changes: a case report and literature review

Background

Gastrointestinal stromal tumors (GISTs) rarely present with predominantly cystic changes. Here, we report a case of giant GIST of the stomach with predominantly cystic changes in a 74-year-old female patient.

Case presentation

The tumor was 10 cm?×?15 cm in size and positive for CD117, H-caldesmon, and DOG-1. Complete surgical resection was performed without regional lymphadenectomy. The patient recovered uneventfully and no recurrence occurred.

Conclusions

The case illustrates that GIST with cystic changes should be considered in the diagnoses of hepatic and pancreatic lesions. Furthermore, immunohistochemistry with CD117, DOG1, and other molecular markers is critical for diagnosis of GIST of the stomach and facilitates optimization of treatments for GIST.

     

Reclassification of gastrointestinal mesenchymal tumors

A retrospective (1985-2005) multicentric evaluation of the pathological diagnoses of GIST (gastrointestinal stromal tumor) in Hungary was performed. A large cohort of 463 patients with abdominal mesenchymal tumors was reevaluated with the help of immunohistochemistry for CD117, CD34, desmin and S100. Prognostic groups have been established based on international criteria. Two hundred fifty five GISTs have been found in 245 patients during the evaluated period. Beside GIST, 81 leiomyogenic and 25 neurogenic tumors were the primary pathological diagnosis and in 74/255 cases the primary diagnosis was a benign tumor. In our cohort high-risk GIST cases were found to be the predominant. Based on our experience, in case of abdominal tumors of uncertain localization, immunohistochemical markers of CD117, CD34, S100 and desmin provide a proper tool for precise identification of the tumor entity including GIST.     

c-kit和PDGFRA基因对胃肠间质瘤的影响

胃肠间质瘤(gastrointestinal stromal tumors,GIST)是较常见的人消化道间叶性肿瘤,多发于胃部.尽管有不同临床病理特征,但绝大多数GIST均存在c-kit或血小板衍生生长因子受体α(PDGFRA)基因突变. c-kit、PDGFRA的抑制剂—格列卫是目前主要应用于GIST治疗的分子靶向治疗药物,c-kit、PDGFRA的不同基因状态会对分子靶向治疗药物呈现不同的反应.c-kit基因外显子11发生突变的GIST对格列卫呈现良好的反应,而外显子 9突变对格列卫的反应略差.另外发现,c-kit、PDGFRA基因的二次突变会引起格列卫抗性.本文简要介绍c-kit、 PDGFRA基因与GIST的临床表现、分子靶向治疗之间的关系及其二次突变的特征.     

Gastrointestinal stromal tumors: key to diagnosis and choice of therapy

The common feature of gastrointestinal stromal tumors (GISTs) is the expression of KIT protein or acquisition of activating, constitutive mutations in the KIT or platelet-derived growth factor receptor alpha (PDGFRA) genes that are the early oncogenic events during GIST development. With these discoveries, GIST has emerged as a distinct sarcoma entity, enabling the introduction of targeted therapy using the inhibition of KIT/PDGFRA and their downstream signaling cascade. The introduction of a small-molecule tyrosine kinase inhibitor, imatinib mesylate, to clinical practice has revolutionized the treatment of patients with advanced GISTs and is currently approved as first-line treatment for patients with metastatic and/or inoperable GISTs. Mutation screening is currently a tool in GIST diagnosis, assessment of sensitivity to tyrosine kinase inhibitors, and prediction of achieving response to molecularly targeted therapy.This article discusses the histologic and molecular criteria for distinguishing GISTs from other types of sarcoma, and the molecular diagnostic tools that are currently available or in development to assist in therapy decisions.     

Prognostic Indicators for Gastrointestinal Stromal Tumors: A Review

Gastrointestinal stromal tumors (GISTs) are potentially malignancies that can occur anywhere in the digestive tract. Tyrosine kinase inhibitors (TKIs) such as imatinib have proven effective since the discovery of KIT and PDGFRA. The current version of NCNN, ESMO and EURACAN guidelines recognized that the three main prognostic factors are the mitotic rate, tumor size and tumor site. In addition, tumor rupture is also recognized as an independent risk factor. However, recent evidence shows that various types of gene mutations are associated with prognosis, and influencing factors such as gastrointestinal bleeding and high Ki67 index have been associated with poor prognosis. It shows that the current risk classification is still insufficient and controversial. With the emergence of more and more lack mutation in KIT/PDGFRA GISTs (KIT/PDGFRA wild-type GISTs) or drug resistance genes, primary and secondary drug resistance problems are caused, which makes the treatment of late or metastatic GIST face challenges. Therefore, this article will review the clinicopathological characteristics of GIST, the special molecular subtypes and other factors that may affect prognosis. We will also explore reliable prognostic markers for better postoperative management and improve the prognosis of patients with GIST.     

Co-expression of monocarboxylate transporter 1 (MCT1) and its chaperone (CD147) is associated with low survival in patients with gastrointestinal stromal tumors (GISTs)

Monocarboxylate transporters (MCTs) have been described to play an important role in cancer, but to date there are no reports on the significance of MCT expression in gastrointestinal stromal tumors (GISTs). The aim of the present work was to assess the value of MCT expression, as well as co-expression with the MCT chaperone CD147 in GISTs and evaluate their clinical-pathological significance. We analyzed the immunohistochemical expression of MCT1, MCT2, MCT4 and CD147 in a series of 64 GISTs molecularly characterized for KIT, PDGFRA and BRAF mutations. MCT1, MCT2 and MCT4 were highly expressed in GISTs. CD147 expression was associated with mutated KIT (p?=?0.039), as well as a progressive increase in Fletcher's Risk of Malignancy (p?=?0.020). Importantly, co-expression of MCT1 with CD147 was associated with low patient's overall survival (p?=?0.037). These findings suggest that co-expression of MCT1 with its chaperone CD147 is involved in GISTs aggressiveness, pointing to a contribution of cancer cell metabolic adaptations in GIST development and/or progression.     

Malignant epithelioid gastrointestinal stromal tumors: report of a case with cytologic and immunohistochemical studies

BACKGROUND: Gastrointestinal stromal tumors (GISTs) may exhibit a fusiform, epithelioid or mixed pattern of growth. Only rare articles report the cytologic and immunohistochemical features of malignant epithelioid tumors. CASE: A 57-year-old woman presented with a tumor mass in the small intestine omentum measuring 8 x 7 cm; it was surgically removed. Five years later 2 mesenteric relapses were studied by fine needle aspiration biopsy and later surgically excised. Cytologically the smears contained small clusters of epithelioid and plasmacytoid cells with round nuclei. The presence of nucleoli and occasional nuclear grooves were prominent. Focally the background was myxoid. Histologically the tumor showed an epithelioid pattern with moderate pleomorphism and mitoses in 6 of 50 high-power fields. Immunohistochemical study showed positivity for c-kit (CD117), vimentin, smooth muscle actin and caldesmon, and focally for desmin and cytokeratin. CONCLUSION: This case illustrates the difficulty in making a reliable diagnosis of the epithelioid variant of GIST by cytology alone. The immunohistochemical panel (apart from c-kit) should include smooth muscle markers and cytokeratins because they are more likely to be reactive. A complete cytoimmunohistochemical evaluation is mandatory to make an accurate diagnosis.     

Analysis of KIT mutation and protein expression in fine needle aspirates of gastrointestinal stromal/smooth muscle tumors

OBJECTIVE: To determine if sequencing the KIT gene could facilitate more definitive FNA diagnosis. STUDY DESIGN: Sixteen cases of gastrointestinal stromal/smooth muscle tumor (GIST) in which fine needle aspiration (FNA) was performed (mean age, 67; M/F = 12/4) were studied. DNA was extracted from cytologic preparations from all patients (15 cell blocks, 1 alcohol-fixed smear) and seven subsequent resection specimens. DNA was amplified by polymerase chain reaction, using primers designed to amplify a segment of the KIT gene exon 11 and sequenced on an ABI Prism 377 DNA sequence analyzer (Applied Biosystems, Indianapolis, Indiana, U.S.A.). Immunocytochemical staining for CD 117 (the KIT gene product) was performed on sections from 12 cell blocks and 7 surgical resections. RESULTS: In-frame deletion of exon 11 was detected in eight cases (7 monoalleic, 1 bialleic); a point mutation was found in one case. Mutation was found only in histologically malignant (6 of 10 cases) and borderline GISTs (3 of 4 cases). No mutation was identified in benign tumors. In three cases, scant cellularity or blood precluded sequencing. CD 117 was expressed in 12 of 15 cases. CONCLUSION: Immunocytochemical staining for CD 117 is useful in confirming a cytologic diagnosis of GIST but does not facilitate diagnosis of malignancy. FNA biopsy specimens are suitable for KIT gene sequencing; detection of a KIT mutation favors a malignant diagnosis, though absence of mutation does not preclude malignancy.     

CD117、CD34、DOG-1、WT-1 在胃肠道间质瘤中的表达及意义

目的:探讨DOG-1、CD117、CD34、WT-1在胃肠道间质瘤(GIST)中的表达及临床意义。方法:应用免疫组织化学SP法检测DOG-1、CD117、CD34、WT-1在39例GIST患者肿瘤组织中的表达。结果:GIST光镜下主要由梭形细胞和(或)上皮样细胞或多形性细胞混合或单一性组成。DOG-1、CD117、CD34和WT-1在GIST肿瘤组织中阳性表达率分别为92.3%(36/39)、71.7%(28/39)、64.1%(25/39)、23.1%(9/39),四者的阳性表达率在各风险程度组(极低及低度危险性GIST、中度危险性GIST、高度危险性GIST)两两比较中差异均无统计学意义(P>0.05)。DOG-1与CD117相比,在极低及低度危险组中表达有显著差异(P<0.05),DOG-1与CD34相比,在极低及低度危险组、高度危险组中表达有显著差异(P<0.05);WT-1与CD117相比,在中度及高度危险组中表达有显著差异(P<0.05),WT-1与CD34相比,在中度危险组中表达有显著差异(P<0.05)。对照组平滑肌瘤、纤维瘤、神经鞘瘤中CD117、DOG-1在GIST中的表达明显高于其他多种梭形细胞的表达(P<0.05)。结论:DOG1是GIST较为敏感和特异的标记物,WT-1在极低及低度危险性GIST中有一定的诊断价值,在GIST的诊断中加入两者将使患者更加受益。     

Fine needle aspiration of gastrointestinal stromal tumors

OBJECTIVE: Gastrointestinal stromal tumors (GISTs) are uncommon mesenchymal tumors of the gastrointestinal tract. Fine needle aspiration (FNA) is one option for diagnosing GISTs before surgery. This study was designed to evaluate the clinical utility of FNA in the diagnosis of GISTs. STUDY DESIGN: FNAs from 19 GISTs originating in the stomach, small bowel and colon obtained from 1988 to 1998 were studied. Immunocytochemistry was performed on 12 cases. The GISTs were classified as benign, borderline and malignant, according to location, size, mitotic activity and clinical outcome. RESULTS: Benign (three) and borderline (five) GISTs were all spindle cell type; malignant GISTs included five spindle cell type and six epithelioid type. Most smears contained abundant cellular material. Benign and borderline GISTs of spindle cell type tended to have cells arranged in tightly cohesive clusters, while malignant GISTs were more likely to exhibit loosely cohesive groups with many single cells, occasional nuclear pleomorphism, hyperchromasia and irregular nuclear contours. Epithelioid-type GISTs mimicked adenocarcinoma. Mitoses were seldom observed in either type. CD117 (KIT protein product) was demonstrated by immunocytochemistry in 9 cases, CD34 in 11, desmin in 3, S-100 protein in 2 and smooth muscle actin in 6 cases. CONCLUSION: FNA can be used to diagnose GISTs as spindle cell and epithelioid types, but cytomorphology alone cannot be used to assess malignant potential. Immunocytochemical staining for CD117 is helpful in confirming the diagnosis. Care must be taken to differentiate epithelioid-type GISTs from adenocarcinoma.     

Quantitative evaluation of immunohistochemical staining in gastrointestinal stromal tumors

OBJECTIVE: To evaluate the differences among pathologists' interpretations in gastrointestinal stromal tumors (GISTs) and to demonstrate the usefulness of quantitative pathology in the assessment of immunohistochemical staining. STUDY DESIGN: Twenty GISTs were separately evaluated by 4 pathologists by the visual estimation method using a 6-antibody panel. Each case was then quantitatively measured with a computer-assisted image analysis system by 2 pathologists. Cohen's kappa test was performed for statistical analysis. RESULTS: All GISTs showed some degree of expression of CD 117, CD34, SMA and Ki-67. No case was immunoreactive for desmin or S-100 protein. There were remarkable differences in the pathologists' visual estimations. Moreover, the discrepancies between visual and quantitative methods were noteworthy. The differences in interpretations showed the greatest variability for Ki-67, which is known to be related to poor prognosis. CONCLUSION: Quantitative pathology in assessment of immunohistochemical staining of GISTs may improve the consistency in the interpretation of staining results and provide some degree of reproducibility.     

GSTT1 Copy Number Gain and ZNF Overexpression Are Predictors of Poor Response to Imatinib in Gastrointestinal Stromal Tumors

Oncogenic mutations in gastrointestinal stromal tumors (GISTs) predict prognosis and therapeutic responses to imatinib. In wild-type GISTs, the tumor-initiating events are still unknown, and wild-type GISTs are resistant to imatinib therapy. We performed an association study between copy number alterations (CNAs) identified from array CGH and gene expression analyses results for four wild-type GISTs and an imatinib-resistant PDGFRA D842V mutant GIST, and compared the results to those obtained from 27 GISTs with KIT mutations. All wild-type GISTs had multiple CNAs, and CNAs in 1p and 22q that harbor the SDHB and GSTT1 genes, respectively, correlated well with expression levels of these genes. mRNA expression levels of all SDH gene subunits were significantly lower (P≤0.041), whereas mRNA expression levels of VEGF (P=0.025), IGF1R (P=0.026), and ZNFs (P<0.05) were significantly higher in GISTs with wild-type/PDGFRA D842V mutations than GISTs with KIT mutations. qRT-PCR validation of the GSTT1 results in this cohort and 11 additional malignant GISTs showed a significant increase in the frequency of GSTT1 CN gain and increased mRNA expression of GSTT1 in wild-type/PDGFRA D842V GISTs than KIT-mutant GISTs (P=0.033). Surprisingly, all four malignant GISTs with KIT exon 11 deletion mutations with primary resistance to imatinib had an increased GSTT1 CN and mRNA expression level of GSTT1. Increased mRNA expression of GSTT1 and ZNF could be predictors of a poor response to imatinib. Our integrative approach reveals that for patients with wild-type (or imatinib-resistant) GISTs, attempts to target VEGFRs and IGF1R may be reasonable options.     

C-kit gene product (CD117) immunoreactivity in canine and feline paraffin sections.

CD117 is a transmembrane tyrosine kinase growth factor receptor expressed by a variety of normal human cell types, including germ cells, immature myeloid cells, and mast cells. To evaluate the pattern of CD117 expression in dogs and cats, we applied a polyclonal antibody on paraffin sections from 44 samples of normal tissues and 104 tumors. In both species, strong immunoreactivity was observed in mast cells, interstitial cells of Cajal, and in mast cell tumors. Among gastrointestinal mesenchymal neoplasms, tissues from five dogs and one cat revealed strong CD117 expression, enabling us to identify them as gastrointestinal stromal tumors (GISTs).     

Functional role of the Ca-activated Cl channel DOG1/TMEM16A in gastrointestinal stromal tumor cells

DOG1, a Ca²⁺-activated Cl⁻ channel (CaCC), was identified in 2004 to be robustly expressed in gastrointestinal stromal tumors (GIST). It was rapidly included as a tumor marker in routine diagnostics, but the functional role remained unknown. CaCCs are important regulators of normal physiological functions, but also implicated in tumorigenesis, cancer progression, metastasis, cell migration, apoptosis, proliferation and viability in several malignancies. We therefore investigated whether DOG1 plays a role in the three latter in GIST by utilizing in vitro cell model systems. Confocal microscopy identified different subcellular localizations of DOG1 in imatinib-sensitive and imatinib-resistant cells. Electrophysiological studies confirmed that DOG1-specific pharmacological agents possess potent activating and inhibiting properties. Proliferation assays showed small effects up to 72 h, and flow cytometric analysis of adherent cells with 7-AAD/Annexin V detected no pharmacological effects on viable GIST cells. However, inhibition of DOG1 conveyed pro-apoptotic effects among early apoptotic imatinib-resistant cells. In conclusion, DOG1 generates Cl⁻ currents in GIST that can be regulated pharmacologically, with small effects on cell viability and proliferation in vitro. Inhibition of DOG1 might act pro-apoptotic on some early apoptotic GIST cell populations. Further studies are warranted to fully illuminate the function of DOG1 and its potential as therapeutic target.     

Diagnostic Value of Immunohistochemical Staining of GP73, GPC3, DCP,CD34, CD31, and Reticulin Staining in Hepatocellular Carcinoma

It has been reported that Golgi protein-73 (GP73), glypican-3 (GPC3), and des-γ-carboxy prothrombin (DCP) could serve as serum markers for the early detection of hepatocellular carcinoma (HCC). This study aimed to evaluate a panel of immunostaining markers (including GP73, GPC3, DCP, CD34, and CD31) as well as reticulin staining to distinguish HCC from the mimickers. Our results revealed that CD34 immunostaining and reticulin staining were highly sensitive for the diagnosis of HCC. A special immunoreaction pattern of GP73—a diffuse coarse-block pattern in a perinuclear region or a concentrated cluster-like or cord-like pattern in a certain part of the cytoplasm—was observed in HCC cells, in contrast to the cytoplasmic fine-granular pattern in surrounding non-tumor cells and non-malignant nodules. This coarse-block pattern correlated significantly with less differentiated HCC. In comparison, GPC3 displayed a good advantage in diagnosing well-differentiated HCC. In our study, DCP and CD31 showed little diagnostic value for HCC as an immunostaining marker. When GP73, GPC3, and CD34 were combined, the specificity improved to 96.6%. Our findings demonstrate for the first time that the immunohistochemical panel of GP73, GPC3, and CD34 as well as reticulin staining is highly specific for the pathological diagnosis of HCC.     

Integrated analysis of long non-coding RNAs and mRNAs associated with malignant transformation of gastrointestinal stromal tumors

Malignant transformation of gastrointestinal stromal tumors (GISTs) is correlated with poor prognosis; however, the underlying biological mechanism is not well understood. In the present study, low-risk (LR) GISTs, GISTs categorized as high-risk based on tumor size (HBS), and on mitotic rate (HBM) were collected for RNA sequencing. Candidate hub lncRNAs were selected by Oncomine analysis. Expression of a selected hub lncRNA, DNM3OS, and its correlation with patients’ prognosis were analyzed using FISH staining, followed with the determination of function and underlying mechanism. Our results revealed a series of key pathways and hub lncRNAs involved in the malignant transformation of GISTs. Oncomine analysis revealed a tight association between clinical signatures and DNM3OS and suggested that DNM3OS is a hub lncRNA that is involved in the Hippo signaling pathway. In addition, DNM3OS was upregulated in HBS, HBM, and HBS/M GIST and correlated with worse prognosis in patients with GISTs. In addition, DNM3OS promoted GIST cell proliferation and mitosis by regulating the expression of GLUT4 and CD36. Collectively, these results improve our understanding of the malignant transformation of GISTs and unveil a series of hub lncRNAs in GISTs.Subject terms: Sarcoma, Long non-coding RNAs