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Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract, frequently characterized by mutations in the KIT or PDGFRA genes. This case report details the complex clinical course of a 71-year-old female with a history of HIV and metastatic GIST presenting with acute abdominal symptoms indicative of perforated viscus. Initial imaging revealed a massive pneumoperitoneum and a large abdominal mass, necessitating immediate surgical intervention. The patient underwent multiple surgeries, including bowel resections and colostomy creation, to address the extensive tumor burden and complications. Postoperatively, she required intensive care management, including mechanical ventilation, vasopressor support, and hemodialysis for acute kidney injury. Pathological examination confirmed metastatic GIST with extensive mesenteric and omental involvement. Immunohistochemical staining was positive for CD117 (c-KIT) and DOG-1. Despite aggressive surgical and supportive measures, the patient's condition highlighted the significant challenges in managing advanced GIST with perforation. This case highlights the importance of a multidisciplinary approach, integrating surgical, medical, and intensive care to optimize outcomes. The prognosis of GIST varies widely, with localized tumors having favorable outcomes following resection, while metastatic cases often face a poorer prognosis despite advances in targeted therapies. This case exemplifies the critical need for personalized treatment plans and ongoing research to improve the management and prognosis of GIST patients.

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Background Gastrointestinal stromal tumors (GISTs) arise from Cajal's interstitial cell precursors and display a variety of genetic mutations, primarily in the KIT and PDGFRA genes. These mutations are linked to tumor location, prognosis, and response to treatment. This study delves into the mutational patterns of GISTs in a Mexican population and their impact on overall survival (OS) and disease-free survival (DFS). Methodology This retrospective study examined 42 GIST cases diagnosed at the Oncology Hospital of the National Medical Center XXI Century between January 2018 and December 2020. Clinical, histological, and immunohistochemical data were gathered, and mutational analysis of KIT and PDGFRA genes was conducted using second-generation sequencing. Results The study group consisted of 52.4% females and 47.6% males, with an average age of 62.6 years. The most common tumor site was the stomach (59.5%), followed by the small intestine (26.2%). KIT mutations were detected in 71.4% of cases, predominantly involving exon 11. PDGFRA mutations were observed in 7.1% of cases. Recurrence was noted in 9.5% of patients, all with high-risk tumors. No significant link was identified between specific mutations and OS or DFS. Conclusions This investigation sheds light on the genetic landscape of GISTs in the Mexican population. While no significant association was established between particular mutations and survival outcomes, the study emphasizes the importance of molecular profiling in treatment decision-making. Further studies with larger sample sizes and longer follow-up periods are necessary to validate these results and explore their clinical relevance.

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Classic colon carcinomas are defined as adenocarcinomas, characterized by groups of medium/large cells with basophilic and polymorphous nuclei and an eosinophilic elongated cytoplasm, that rearrange on glandular structures. Signs of poor prognosis include high tumor budding, lymphovascular and perineural invasion, poor differentiation, positive margins, and CDX2 loss. Less frequent colon carcinoma subtypes are: mucinous, medullary, signet-ring cell, squamous cell, small cell and undifferentiated carcinoma, among others. In the following case report, we present a 65-year-old woman with a T2N0Mx colon carcinoma with a remarkable papillary and follicular histological appearance. The immunohistochemical stains confirmed an intestinal origin (CDX2+) and excluded a thyroid, gynecological, and urological metastasis, with tumor cells negative for GATA3, PAX8, TTF-1, and thyroglobulin. There was no loss of mismatch repair proteins and p53 showed a wild-type staining. next generation sequencing showed a platelet-derivated growth factor receptor alpha (PDGFRA) mutation. To the best of our knowledge, there have been only two examples of primary papillary colon carcinoma reported in the literature, and neither of them with a PDGFRA mutation. We describe one tumor and discuss its pathological features.

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A 49-year-old man with abdominal pain was referred to our hospital. Abdominal computed tomography showed an extraluminal tumor near the gastric anterior wall and intra-abdominal fluid collection. A ruptured intra-abdominal tumor was suspected, and emergency abdominal angiography was performed. Hemorrhage into the abdominal cavity was seen, and transcatheter arterial embolization (TAE) was performed, which stopped the bleeding. The tumor was surgically resected, and a diagnosis of an extraluminally growing gastric gastrointestinal stromal tumor was made. TAE should be considered for rare cases of extraluminally growing tumors with intra-abdominal hemorrhage.

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BACKGROUND: The patient selection for optimal adjuvant therapy in gastrointestinal stromal tumors (GISTs) is provided by nomogram based on tumor size, mitotic index, tumor location, and tumor rupture. Although mutational status is not currently used to risk assessment, tumor genotype showed a prognostic influence on natural history and tumor relapse. Innovative measures, such as KIT/PDGFRA-mutant-specific variant allele frequency (VAF) levels detection from next-generation sequencing (NGS), may act as a surrogate of tumor burden and correlate with prognosis and overall survival of patients with GIST, helping the choice for adjuvant treatment. PATIENTS AND METHODS: This was a multicenter, hospital-based, retrospective/prospective cohort study to investigate the prognostic role of KIT or PDGFRA-VAF of GIST in patients with radically resected localized disease. In the current manuscript, we present the results from the retrospective phase of the study. RESULTS: Two-hundred (200) patients with GIST between 2015 and 2022 afferent to 6 Italian Oncologic Centers in the EURACAN Network were included in the study. The receiver operating characteristic (ROC) curves analysis was used to classify "low" vs. "high" VAF values, further normalized on neoplastic cellularity (nVAF). When RFS between the low and high nVAF groups were compared, patients with GIST with KIT/PDGFRA nVAF > 50% showed less favorable RFS than patients in the group of nVAF ≤ 50% (2-year RFS, 72.6% vs. 93%, respectively; P = .003). The multivariable Cox regression model confirmed these results. In the homogeneous sub-population of intermediate-risk, patients with KIT-mutated GIST, the presence of nVAF >50% was statistically associated with higher disease recurrence. CONCLUSION: In our study, we demonstrated that higher nVAF levels were independent predictors of GIST prognosis and survival in localized GIST patients with tumors harboring KIT or PDGFRA mutations. In the cohort of intermediate-risk patients, nVAF could be helpful to improve prognostication and the use of adjuvant imatinib.

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Epithelioid gastrointestinal stromal tumors (GISTs) are rare and may be confused with other tumors with epithelioid morphology. Therefore, herein, we collected 12 epithelioid GIST samples and summarized their morphological and immunohistochemical characteristics. Through genetic testing, we explored the correlation between morphology and gene mutations. The results showed that eight tumors showed focal or diffuse myxoid stromal changes with less cohesively arranged rhabdoid tumor cells; among these, five showed platelet-derived growth factor receptor alpha gene (PDGFRA) mutations. Signet ring cells with sclerosing stroma and receptor tyrosine kinase type III gene (KIT) mutations were present in two cases, which might be a KIT mutation-associated growth pattern in epithelioid GISTs. Succinate dehydrogenase gene (SDH) mutations were detected in three cases. Simultaneously, PDGFRA mutations were detected in two cases, and the Kirsten rat sarcoma viral oncogene homolog gene (KRAS) mutation was detected in another case. SDH-subunit B (SDHB) expression was partially weak and strongly diffuse in two cases with concurrent PDGFRA and SDHD mutations, respectively. The coexistence of PDGFRA and SDHD mutations may have affected SDHB expression. Altogether, we concluded that PDGFRA mutations may play an important role in co-mutant GIST pathogenesis.

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BACKGROUND: Metanephric stromal tumors (MST) are rare benign renal tumors that mainly occur in infants and children. Approximately 72% of MST in children have the B-Raf proto-oncogene serine/threonine kinase (BRAF) V600E mutation. To date, only five cases of adult MSTs have been reported and no clear genetic alterations have been found. CASE PRESENTATION: We report a case of MST in a 45-year-old woman who complained of left lower back pain for a week, accompanied by hypertension (150/79 mmHg). Magnetic resonance imaging (MRI) showed an abnormally enhanced nodule (1.1 cm in the middle of the left kidney), which was histopathologically consistent with an MST. The BRAF V600E mutation was not detected in tumor cells using PCR and next-generation sequencing (NGS). However, a platelet-derived growth factor receptor alpha (PDGFRA) mutation was detected in this case using NGS. The patient showed no recurrence or metastasis nine months after partial nephrectomy, and her blood pressure was consistently normal. CONCLUSION: This is the first report of alterations in PDGFRA in MSTs. This result advances our knowledge of genetic variations in adult MSTs, which may have different gene alterations from MSTs in children.

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Platelet-derived growth factor receptor A (PDGFRA) mutations occur in approximately 10-15% of gastrointestinal stromal tumors (GISTs). These tumors with PDGFRA mutations have a different pathogenesis, clinical characteristics, and treatment response compared to tumors with receptor tyrosine kinase protein (KIT) mutations (60-70%). Many clinical studies have investigated the use of tyrosine kinase inhibitors mainly in patients with KIT mutations; however, there is a lack of attention to the PDGFRA-mutated molecular subtype. The main effective inhibitors of PDGFRA are ripretinib, avapritinib, and crenolanib, and their mechanisms and efficacy in GIST (as confirmed in clinical trials) are described in this review. Some multi-targeted tyrosine kinase inhibitors with inhibitory effects on this molecular subtype are also introduced and summarized in this paper. This review focuses on PDGFRA-mutated GISTs, introduces their clinical characteristics, downstream molecular signaling pathways, and existing resistance mechanisms. We focus on the most recent literature that describes the development of PDGFRA inhibitors and their use in clinical trials, as well as the potential benefits from different combination therapy strategies.

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Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the canine gastrointestinal tract and are diagnosed by the immunohistochemical expression of the receptor tyrosine kinase (RTK) KIT. Activating mutations of the proto-oncogenes c-KIT and PDGFRA drive GIST oncogenesis and are used to predict the response to RTK-inhibitors in human oncology. Currently, the frequency and significance of these mutations in canine GIST have not been adequately explored. Therefore, we investigated the mutational status of c-KIT (exons 9, 11 and 13) and PDGFRA (exons 12 and 18) genes by PCR followed by fragment analysis for c-KIT deletions and PCR followed by screening with DHPLC and direct sequencing confirmation for single nucleotide variations in 17 formalin-fixed paraffin-embedded canine GISTs confirmed by KIT immunopositivity. c-KIT mutations were detected in 47% of cases, with a mutation detection rate significantly higher (p = 0.0004, Fisher's exact test) and always involving exon 11. A PDGFRA gene mutation (exon 18) was identified in one case. Even if follow-up data were not available for all cases, four cases with documented abdominal metastases displayed c-KIT mutations. These data confirm that c-KIT exon 11 mutations occur frequently in canine GISTs, and identify the presence of a PDGFRA mutation similar to human GISTs. This study also suggests a potential association of c-KIT mutation with more aggressive biological behavior.

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Introduction: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the digestive tract. Presentation of case: 54-year-old woman with a history of phyllodes tumor of the left breast he patient was admitted to our hospital for management of retroperitoneal soft tissue tumor, attached to the fourth portion of the duodenum, opposite the head of the pancreas. The patient underwent a large excision of the tumor, the duodenojejunal flexure, and the third and fourth portions of the duodenum along with the head of the pancreas. The histopathological examination confirmed the presence of a spindlecell mesenchymal proliferation. These cells do not express CD117, but they express DOG1. A PDGFRA mutation was identified later. The final diagnosis was duodenal GIST. Discussion: few cases of GIST in the fourth portion of the duodenum had been reported in the literature. PDGFRA mutation is identified as GISTs tumorigenesis to 15% of cases, and the diagnosis of GISTs is not based solely on the expression of the protein Kit. Conclusion: the molecular biology examinations are very helpful in the direction of the correct diagnosis in case of negative staining for CD117.

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Gastrointestinal stromal tumour (GIST) is the most common sarcoma and can be seen in any part of the gastrointestinal tract. The effect of tyrosine kinase inhibitors varies with mutation status in receptor tyrosine kinase KIT and in platelet-derived growth factor receptor A (PDGFRA). This case presents a 61-year-old man, diagnosed with an 11-cm GIST located at the stomach with a high risk of recurrence. The patient showed intolerance to imatinib shortly after introduction and subsequently progressed on sunitinib and nilotinib. The patient started fourth-line treatment with sorafenib with an impressive response to a point at which metastases intra-abdominally and in the liver could be resected. After surgery, sorafenib was restarted. Due to toxicity, sorafenib dose was reduced over time. The dose was insufficient to control the disease since a new recurrence was detected. Mutation analyses revealed a GIST harbouring a deletion of codon p.I843_D846del, located at PDGFRA exon 18, right next to the codon D842 where mutations are known leading to imatinib resistance. In this case, the GIST was highly sensitive to sorafenib, and the response was dose related. It is mandatory to perform mutation analyses on primary tumour and at recurrence in the decision-making of the correct treatment for the patient. In March 2021, the patient had been in treatment with sorafenib for 12.5 years and was still without signs of recurrence. A multidisciplinary approach was essential for the long-term survival of the patient in this case.

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Purpose: To explore molecular alterations and their correlation with the survival of patients with glioblastoma (GBM) with corpus callosum (CC) involvement (ccGBM). Methods: Electronic medical records were reviewed for glioma patients tested for molecular alterations and treated at our hospital between January 2016 and July 2020. ccGBM was compared to GBM without CC involvement (non-ccGBM) to identify differences in molecular alterations. Clinical outcomes and survival were compared between ccGBM and non-ccGBM patients, as well as among patients with ccGBM with different molecular alteration statuses. ccGBM was also compared to diffuse midline glioma (DMG) to clarify their correlation in molecular alterations, the progression-free survival (PFS), and overall survival (OS). Results: Thirty ccGBM and 88 non-ccGBM patients were included. PDGFRA amplification (PDGFRAamp, 33.3 vs. 9.1%, P = 0.004) and missense mutation (PDGFRAmut, 20.0 vs. 3.4%, P = 0.011) both had higher incidences in ccGBM than in non-ccGBM. PDGFRA alteration was associated with the occurrence of ccGBM (OR = 4.91 [95% CI: 1.55-15.52], P = 0.007). ccGBM with PDGFRAamp resulted in a shorter median PFS (8.6 vs. 13.5 months, P = 0.025) and OS (12.4 vs. 17.9 months, P = 0.022) than non-ccGBM with PDGFRAnon-amp. ccGBM with PDGFRAamp combined with PDGFRAmut (PDGFRAamp-mut) had a shorter median PFS (7.6 vs. 8.9 months, P = 0.022) and OS (9.6 vs. 17.8 months, P = 0.006) than non-ccGBM with wild-type PDGFRA and no amplification (PDGFRA-w, non-amp). Compared to ccGBM with PDGFRA-w, non-amp, ccGBM with PDGFRAamp and PDGFRAamp-mut both had a shorter median PFS and OS (P < 0.05). The hazard ratios (HRs) of PDGFRAamp for PFS and OS in ccGBM were 3.08 (95% CI: 1.02-9.35, P = 0.047) and 5.07 (1.52-16.89, P = 0.008), respectively, and the HRs of PDGFRAamp-mut for PFS and OS were 13.16 (95% CI: 3.19-54.40, P < 0.001) and 16.36 (2.66-100.70, P = 0.003). ccGBM may have similar incidences of PDGFRAamp or mut (PDGFRAamp/mut) as DMG, and they also had similar median PFS (10.9 vs. 9.0 months, P = 0.558) and OS (16.8 vs. 11.5 months, P = 0.510). Conclusion: PDGFRA alterations are significantly associated with the occurrence and poor prognosis of ccGBM. ccGBM with PDGFRAamp/mut may be classified as a single subtype of GBM that has a similar survival rate to DMG. PDGFR inhibitors may be a promising treatment method for ccGBM.

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A 21-year-old female presented with a 5-year history of an erythematous papule on her right breast. The biopsy showed a dense, dermal nodular infiltrate, extending focally into the subcutaneous tissue. The infiltrate was composed predominantly of pleomorphic cells with bi-lobed, multi-lobed, horseshoe, or ring-shaped nuclei. There was a smaller subset of monomorphous cells characterized by a round, reniform, or elongated single-lobed nucleus. Accompanying cells included few foamy histiocytes, lymphocytes, and numerous scattered eosinophils. No necrosis, vascular invasion, or ulceration was present. The pleomorphic and monomorphic granular cells were positive for Giemsa stain as well as for tryptase, CD117, CD68, CD2, and CD30 immunohistochemistry and negative for S100, CD1a, myeloperoxidase, lysozyme, and CD56. Clinical examination was negative for any additional similar lesions and serum tryptase was within normal limits. The bone marrow was not biopsied. In addition, fluorescent in situ hybridization revealed multiple clones with loss of number 5 chromosome and PDGFRA and HRAS mutations. The lesion did not recur or progress after a 6-year clinical follow-up. To our full knowledge, we report the first case of pleomorphic mastocytoma with loss of chromosome 5 and PDGFRA and HRAS mutations.

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Introduction: The benefit of the tyrosine kinase inhibitor (TKI) imatinib mesylate in metastatic Gastrointestinal Stromal Tumors (GIST) leads to improved progression-free survival (PFS) and overall survival (OS). Clinical trials of adjuvant imatinib have provided data on the utility in management of primary GIST. There still remains uncertainty regarding the optimal duration of therapy.Areas covered: Here, we review the literature on the pivotal clinical trials evaluating adjuvant imatinib: ACOSOG Z9000/Z9001, EORTC 62024, Scandinavian Sarcoma Group XVIII, and PERSIST-5. The data from these studies that were analyzed included the patient population, length of therapy, and outcomes.Expert opinion: Clinical trial data demonstrate that adjuvant imatinib delays recurrence and appears to improve survival when taken for 3 years in high-risk patients; treatment for 5 years has been found to be safe, although difficult for patients to maintain adherence. These studies all incorporated slightly different patient populations based upon eligibility criteria for risk of recurrence, but support the use in patients with intermediate to high risk of disease recurrence. Data from these studies does not support treating those with low risk of recurrence or imatinib-insensitive mutations.

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Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors in the gastrointestinal tract although they are much less frequent than epithelial tumors. In more than 60% of cases they occur in the stomach. Especially small lesions measuring ≤1 cm in diameter, so-called microscopic GIST can occur multifocally, frequently in the proximal stomach wall and sometimes as an incidental finding in a gastrectomy specimen resected for gastric cancer. The multicentricity of GIST alone is not proof of a metastatic behavior or a syndromal or hereditary disease. Multiple sporadic synchronous and metachronous GIST are characterized by different primary mutations mostly in the KIT or PDGFRA genes and are often less aggressive. It is speculative whether a field effect is responsible or whether still unknown GIST-promoting factors may facilitate the development of several independent lesions. If KIT or PDGFRA mutations are lacking, a succinate dehydrogenase (SDH) deficient GIST has to be considered, either hereditary as Carney-Stratakis syndrome or syndromal as part of a Carney triad.

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Pediatric high-grade glioma (HGG, WHO Grade III and IV) is a devastating brain tumor with a median survival of less than two years. PDGFRA is frequently mutated/ amplified in pediatric HGG, but the significance of this finding has not been fully characterized. We hypothesize that alterations of PDGFRA will promote distinct prognostic and treatment implications in pediatric HGG. In order to characterize the impact of PDGFR pathway alterations, we integrated genomic data from pediatric HGG patients (n=290) from multiple pediatric datasets and sequencing platforms. Integration of multiple human datasets showed that PDGFRA mutation, but not amplification, was associated with older age in pediatric HGG (P= <0.0001). In multivariate analysis, PDGFRA mutation was correlated with worse prognosis (P = 0.026), while PDGFRA amplification was not (P = 0.11). By Kaplan-Meier analysis, non-brainstem HGG with PDGFRA amplification carried a worse prognosis than non-brainstem HGG without PDGFRA amplification (P = 0.021). There were no pediatric patients with PDGFRA-amplified HGG that survived longer than two years. Additionally, we performed paired molecular profiling (germline / tumor / primary cell culture) and targeting of an infant thalamic HGG with amplification and outlier increased expression of PDGFRA. Dasatinib inhibited proliferation most effectively. In summary, integration of the largest genomic dataset of pediatric HGG to date, allowed us to highlight that PDGFRA mutation is found in older pediatric patients and that PDGFRA amplification is prognostic in non-brainstem HGG. Future precision-medicine based clinical trials for pediatric patients with PDGFRA-altered HGG should consider the optimized delivery of dasatinib.

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The first 15 years of management of gastrointestinal stromal tumor (GIST) have led to 3 lines of therapy for metastatic disease: imatinib, sunitinib, and regorafenib. In the adjuvant setting, imatinib is usually given for 3 years postoperatively to patients with higher-risk primary tumors that are completely resected. In this review, issues regarding GIST adjuvant therapy are discussed. It is hoped this review will help the reader understand the present standard of care to improve upon it in years to come.

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OBJECTIVE: Gastrointestinal stromal tumors (GISTs) with no mutations in exons 9, 11, 13, and 17 of the KIT gene and exons 12, and 18 of the PDGFRA gene were defined as KIT/PDGFRA wild-type and they accounted for ~15-20% of GISTs. However, some KIT/PDGFRA wild-type GISTs with KIT mutations in other exons were occasionally reported. We therefore assessed GISTs to understand the whole genomic genotypes of KIT or PDGFRA genes in KIT/PDGFRA wild-type GISTs. METHODS: A cohort of 185 KIT/PDGFRA wild-type GISTs from 1,080 cases was retrospectively assessed. Thirty-nine patients were excluded due to insufficiency of genomic DNA data or failure of library preparation, and 146 patients were analyzed by targeted next-generation sequencing (NGS) followed by validation. RESULTS: For hot spots in KIT and PDGFRA genes, 23 out of 146 KIT/PDGFRA wild-type cases carried mutations according to NGS; there were 19 KIT mutations and 4 PDGFRA mutations, and these were exclusive. Intratumoral KIT mutational heterogeneity was observed in 4 of 19 samples which potentially triggered mechanisms of polyclonal evolution and metastasis and drug sensitivity. Eleven patients treated with imatinib were evaluable for clinical response, and 2 of 3 patients with KIT mutations achieved partial response (PR), while only 1 of 8 patients without KIT mutations reached PR. CONCLUSION: NGS had the potential property to identify partial mutant tumors from a subset of GISTs regarded as KIT/PDGFRA wild-type tumors using Sanger sequencing, and provided a better understanding of KIT/PDGFRA genotypes as well as identified patients eligible for imatinib therapy.

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Gastrointestinal stromal tumor (GIST) is the most frequent mesenchymal tumor of the gastrointestinal tract and one of the most frequent sarcoma. Mutually exclusive KIT and PDGFRA mutations are central events in GIST pathogenesis, and their understanding is crucial because specific treatment targeting oncogenic KIT and PDGFRA activation (especially imatinib) has become available. The most frequent PDGFRA mutation (D842V) is associated with primary resistance to imatinib. Data related to regorafenib efficacy in PDGFRA-mutated GIST are lacking. We report here a case report of a prolonged response with regorafenib in a patient with a PDGFRA-mutated GIST.

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AIMS: Rhabdoid morphology resembling that of the aggressive paediatric rhabdoid tumours occurs in various malignancies usually lacking characteristic SMARCB1 (INI1) loss. Little is known about the clinicopathological and molecular characteristics of the rhabdoid phenotype in gastrointestinal stromal tumours (GISTs). METHODS AND RESULTS: Six gastric rhabdoid GISTs were examined by immunohistochemistry, KIT and platelet-derived growth factor receptor-α gene (PDGFRA) mutation analysis, and comparative genomic hybridization (CGH). All tumours expressed KIT, PDGFRA, DOG-1, and SMARCB1 (two of six with a mosaic pattern). Five of six tumours harboured PDGFRA mutations (D842V in four; N659K in one), and one case was wild type for KIT/PDGFRA and succinate dehydrogenase (SDH) A-negative and SDHB-negative by immunohistochemistry. CGH revealed aberrations typical of GISTs (-1p, -14, and -22q in three, five, and three cases, respectively), with a mean of 1.7 aberrations in the epithelioid component and 2.7 in the rhabdoid component. None showed progression (mean follow-up of 25 months). CONCLUSIONS: Rhabdoid gastric GISTs are associated with epithelioid morphology and PDGFRA mutations. They harbour CGH aberrations that are typical of ordinary GISTs in both tumour components. The presence of additional genetic alterations in the rhabdoid areas indicates evolution from the epithelioid components, and possible genetic and biological progression. On the basis of our series and previous reports, rhabdoid morphology in GISTs presumably does not imply aggressiveness.

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