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V600E BRAF mutations are alternative early molecular events in a subset of KIT/PDGFRA wild-type gastrointestinal stromal tumours

Agaimy, A. and Terracciano, L. M. and Dirnhofer, S. and Tornillo, L. and Foerster, A. and Hartmann, A. and Bihl, M. P.. (2009) V600E BRAF mutations are alternative early molecular events in a subset of KIT/PDGFRA wild-type gastrointestinal stromal tumours. Journal of clinical pathology : the journal of the Association of Clinical Pathologists, Vol. 62. pp. 613-316.

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Official URL: http://edoc.unibas.ch/dok/A6005035

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Abstract

BACKGROUND: A small subset (10-15%) of gastrointestinal stromal tumours (GISTs) lack mutations in KIT and PDGFRA (wild-type GIST). Recently, a novel BRAF exon 15 mutation (V600E) was detected in imatinib-naive wild-type high-risk intestinal GISTs (4%). However, the frequency and distribution of BRAF mutations within the spectrum of GISTs, and whether they might represent secondary events acquired during tumour progression, remain unknown. METHODS: 69 GISTs (39 KIT mutants, 2 PDGFRA mutants and 28 wild-type) were analysed for mutations in BRAF exon 15 and KRAS exon 2. To assess the stage at which these mutations might occur in GIST, a considerable number of incidental gastric (n = 23) and intestinal (n = 2) tumours were included. RESULTS: BRAF mutations (V600E) were detected in 2 of 28 wild-type GISTs (7%), but in none of the 41 KIT/PDGFRA mutants. No KRAS mutation was detected. The two BRAF-mutated GISTs measured 4 mm in diameter and originated in the gastric body and the jejunum in two men (mean age, 76 years). Both tumours were mitotically inactive KIT-positive spindle-cell GISTs that were indistinguishable histologically from their more common KIT-mutated counterparts. CONCLUSION: BRAF mutations represent an alternative molecular pathway in the early tumorigenesis of a subset of KIT/PDGFRA wild-type GISTs and are per se not associated with a high risk of malignancy. Mutations in KIT, PDGFRA and BRAF were mutually exclusive in this study. Results from this and a previous study indicate that BRAF-mutated GISTs show a predilection for the small bowel (four of five tumours), but this needs further evaluation in larger studies.
Faculties and Departments:03 Faculty of Medicine > Bereich Querschnittsfächer (Klinik) > Pathologie USB
03 Faculty of Medicine > Departement Klinische Forschung > Bereich Querschnittsfächer (Klinik) > Pathologie USB
03 Faculty of Medicine > Bereich Querschnittsfächer (Klinik) > Pathologie USB > Histopathologie (Dirnhofer)
03 Faculty of Medicine > Departement Klinische Forschung > Bereich Querschnittsfächer (Klinik) > Pathologie USB > Histopathologie (Dirnhofer)
03 Faculty of Medicine > Bereich Querschnittsfächer (Klinik) > Pathologie USB > Molekulare Pathologie (Terracciano)
03 Faculty of Medicine > Departement Klinische Forschung > Bereich Querschnittsfächer (Klinik) > Pathologie USB > Molekulare Pathologie (Terracciano)
UniBasel Contributors:Dirnhofer, Stephan and Terracciano, Luigi M. and Tornillo, Luigi
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:British Medical Association
ISSN:0021-9746
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:01 Feb 2013 08:46
Deposited On:01 Feb 2013 08:42

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