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Rhabdoid morphology in gastrointestinal stromal tumours ( GIST s) is associated with PDGFRA mutations but does not imply aggressive behaviour
Author(s) -
Schaefer IngaMarie,
Ströbel Philipp,
Cameron Silke,
Beham Alexander,
Otto Claudia,
Schildhaus HansUlrich,
Agaimy Abbas
Publication year - 2014
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1111/his.12265
Subject(s) - pdgfra , gist , immunohistochemistry , biology , pathology , stromal cell , sdhb , cancer research , mutation , medicine , germline mutation , gene , genetics
Aims Rhabdoid morphology resembling that of the aggressive paediatric rhabdoid tumours occurs in various malignancies usually lacking characteristic SMARCB 1 ( INI 1) loss. Little is known about the clinicopathological and molecular characteristics of the rhabdoid phenotype in gastrointestinal stromal tumours ( GIST s). Methods and results Six gastric rhabdoid GIST s 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 SMARCB 1 (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 GIST s (−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 GIST s are associated with epithelioid morphology and PDGFRA mutations. They harbour CGH aberrations that are typical of ordinary GIST s 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 GIST s presumably does not imply aggressiveness.