Ith tki resistance exon 9 mutations – respond to dose escalation of tkis wild-type-kit gists and exon 9 mutations – more responsive to sunitinib pdgfra gene (platelet-derived growth factor receptor alpha) arup test: gastrointestinal stromal tumor mutation 2002674 characteristics mutations cluster on exons 12, 14, and 18 exon 18 most common therapeutic implications wild-type pdgfra – associated with tki resistance wild-type pdgfra gists – more responsive to sunitinib diagnosis indications for testing patient with gastrointestinal symptoms (satiety, abdominal discomfort due to pain or swelling, intraperitoneal hemorrhage) and suspicious mass on endoscopy or scanning laboratory testing cbc – may demonstrate anemia liver function tests histology gists are soft and fragile tumors; biopsy may cause tumor hemorrhage and possible increased risk for tumor dissemination consideration of biopsy should be based on extent of disease and suspicion of a given histologic subtype immunohistochemistry cd117 (kit) most demonstrate strong and diffuse cytoplasmic staining; may have membranous or paranuclear stain cd117 stains may become weaker after imatinib therapy others cd34 – positive in 80% caldesmon – positive in up to 85% smooth muscle actin (sma) – positive in up to 30% smooth muscle phenotype becomes more common after tyrosine kinase inhibitor (tki) therapy differential markers desmin – rarely seen in gist; usually indicates smooth muscle tumor s-100 protein, glial fibrillary acidic protein (gfap) – seen in schwannomas beta-catenin-1 – seen in desmoid fibromatosis molecular testing – gist mutation analysis kit or pdgfra mutations are characteristic of gist kit immunohistochemistry positivity alone does not confirm diagnosis; other spindle cell neoplasms may be kit positive 5-10% are kit negative (half of these cases show kit or pdgfra genetic mutations) kit-negative gists typically occur in the stomach and show epithelioid or mixed pattern other patient should be evaluated by a multidisciplinary team with expertise in sarcoma imaging studies tumor is often discovered incidentally on imaging ultrasound – endoscopic ultrasound demonstrates hypoechoic mass that is contiguous with the muscularis propria high-risk features include irregular border, cystic spaces, ulceration, echogenic foci, and heterogeneity mri and/or abdominal/pelvic ct with contrast – demonstrates mass and helps define extension of tumor pet scan – may help differentiate active tumor from necrotic or inactive scar tissue, malignant from benign tissue, and recurrent tumor from nondescript benign changes pet is not a substitute for ct but may clarify ambiguous ct or mri findings percutaneous image-guided biopsy may be appropriate for confirmations of metastatic disease prognosi. viagra and effect on blood pressure vision loss due to viagra cheapest generic viagra online generic viagra viagra 25 mg achat generic viagra online viagra pills young men who use viagra This Site is Being Updated

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