title: Myxoid epithelioid gastrointestinal stromal tumor harboring an unreported PDGFRA mutation: report of a case and review of the literature.
abstract: Activating mutations of platelet-derived growth factor receptor α (PDGFRA) are detected in a significant proportion of gastrointestinal stromal tumors (GISTs), in addition to the more frequent mutation in c-kit. GISTs with PDGFRA mutations have been found to have several characteristic morphological features, sometimes allowing to discriminate them from GISTs with c-kit mutations. Among these, epithelioid morphology in tumor cells and tumor-infiltrating mast cells are powerful predictors of PDGFRA mutations. Although myxoid stroma by itself is not so much a reliable predictor of PDGFRA mutation, myxoid stroma in conjunction with epithelioid morphology in tumor cells is a powerful predictor of mutations in this gene. GISTs showing either weak or negative immunoreactivity for c-kit and epithelioid cells with myxoid stroma are called myxoid epithelioid GISTs, which typically show PDGFRA mutation. Herein, we presented a case of a 59-year-old woman with myxoid epithelioid GIST of the stomach. A unique finding in this case was eosinophil infiltration, probably more numerous than mast cells; mast cell infiltration is known to be usually found in myxoid epithelioid GIST. The existence of a similar mechanism in eosinophil and mast cell recruitment via tumor-producing stem cell factor is speculated. Mutational analyses revealed a PDGFRA exon 18 mutation: D842_H845del, D846N. Combined deletion and substitution mutation has been reported in rare instances, but to the best of our knowledge, D846N has not been documented.
authors.affiliation: Department of Pathology, Graduate School of Medicine, The University of Tokyo Tokyo, Japan ; Department of Pathology, Fujieda Municipal General Hospital Shizuoka, Japan.
authors.forename: Shogo
authors.initials: S
authors.lastname: Tajima
authors.affiliation: Department of Gastroenterology, Fujieda Municipal General Hospital Shizuoka, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Ohata
authors.affiliation: Department of Pathology, Fujieda Municipal General Hospital Shizuoka, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Koda
authors.affiliation: Department of Gastroenterology, Fujieda Municipal General Hospital Shizuoka, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Maruyama
mesh_terms: D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000032:analysis / Q000235:genetics*; D001706:Biopsy; D004252:DNA Mutational Analysis; D015622:Epithelioid Cells / Q000737:chemistry / Q000473:pathology; D005091:Exons; D005260:Female; D005743:Gastrectomy; D046152:Gastrointestinal Stromal Tumors / Q000737:chemistry / Q000235:genetics* / Q000473:pathology / Q000601:surgery; D005773:Gastroscopy; D020022:Genetic Predisposition to Disease; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D008969:Molecular Sequence Data; D010641:Phenotype; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics*; D017384:Sequence Deletion; D013274:Stomach Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000473:pathology / Q000601:surgery; D014057:Tomography, X-Ray Computed
chemical_list: D014408:Biomarkers, Tumor; D020796:Receptor, Platelet-Derived Growth Factor alpha
keywords: Myxoid epithelioid gastrointestinal stromal tumor; PDGFRA gene; exon 18; mutation