title: Epithelioid gastrointestinal stromal tumor with PDGFRA activating mutation and immunoreactivity.
abstract: The authors report a unique case of an intra-abdominal, epithelioid mesenchymal tumor that had an activating mutation of PDGFRA and a strong PDGFRA immunoreactivity but lacked both c-kit mutation and c-kit protein (CD117) expression. IHC study showed that the tumor cells were diffusely and strongly positive for PDGFRA, vimentin, CD34, and Bcl-2 but completely negative for CD117 as well as for muscle, epithelial, endothelial, endocrine, mesothelial, neural, and melanocytic cell markers. Molecular study revealed a mutation at the juxtamembrane domain of exon 12 in PDGFRA gene with GTC to GAC transition at codon 561 (V561D), as shown in the previous mutational studies on gastrointestinal stromal tumor (GIST). This case likely represents an example of GIST with PDGFRA activating mutation and PDGFRA immunoreactivity without CD117 positivity, which has not been documented in the literature. STI 571 (imatinib mesylate [Gleevec]) might be an effective therapy in this case, since Gleevec targets both PDGFRA and c-kit oncoproteins.
authors.affiliation: Department of Pathology, University of California San Diego, School of Medicine, San Diego, CA 92103-8720, USA. jeyi@ucsd.edu
authors.forename: Eunhee S
authors.initials: ES
authors.lastname: Yi
authors.forename: Curtis R
authors.initials: CR
authors.lastname: Strong
authors.forename: Zhe
authors.initials: Z
authors.lastname: Piao
authors.forename: Manuel
authors.initials: M
authors.lastname: Perucho
authors.forename: Noel
authors.initials: N
authors.lastname: Weidner
mesh_terms: D000328:Adult; D004252:DNA Mutational Analysis; D046152:Gastrointestinal Stromal Tumors / Q000235:genetics* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000235:genetics* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008297:Male; D009154:Mutation; D019009:Proto-Oncogene Proteins c-kit / Q000276:immunology; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics* / Q000378:metabolism
chemical_list: D019009:Proto-Oncogene Proteins c-kit; D020796:Receptor, Platelet-Derived Growth Factor alpha