Gastrointestinal Stromal TumorsProto-Oncogene Proteins c-kitGastrointestinal NeoplasmsBenzamidesReceptor, Platelet-Derived Growth Factor alphaPiperazinesPyrimidinesDelayed DiagnosisPrenatal DiagnosisEarly DiagnosisSensitivity and SpecificityRetrospective StudiesDiagnosisTomography, X-Ray ComputedEpithelioid CellsPrognosisImmunohistochemistryAntineoplastic AgentsTreatment OutcomeDiagnostic ErrorsLeiomyosarcomaMutationBiopsyPredictive Value of TestsTumor Markers, BiologicalDNA Mutational AnalysisMitotic IndexFollow-Up StudiesMesenchymomaNeoplasms, Multiple PrimaryNursing DiagnosisDiagnosis, Computer-AssistedProspective StudiesReproducibility of ResultsTime FactorsDuodenal NeoplasmsStomach NeoplasmsRisk FactorsPolymerase Chain ReactionBiopsy, NeedleMagnetic Resonance ImagingPreimplantation DiagnosisLeiomyomaChondromaIntestinal NeoplasmsNeoplasms, Connective TissueStromal CellsFatal OutcomeInfant, NewbornSarcomaPyrrolesPregnancySuccinate DehydrogenaseEndosonographyProtein Kinase InhibitorsIncidenceExonsCohort StudiesParaganglioma, Extra-AdrenalDisease ProgressionBiopsy, Fine-NeedleDigestive System Surgical ProceduresElectron Transport Complex IIAge FactorsFetal DiseasesGastrectomyNeurilemmomaInterstitial Cells of CajalSurvival RateNeoplasm StagingSyndromeSurvival AnalysisEndoscopy, GastrointestinalJejunal NeoplasmsNeurofibromatosis 1Ileal NeoplasmsPrevalenceIncidental FindingsFalse Positive ReactionsUltrasonography, PrenatalRisk AssessmentBiological MarkersClinical Laboratory TechniquesAcute DiseaseCase-Control StudiesROC CurveFalse Negative ReactionsDisease-Free SurvivalCarney ComplexIndolesAntigens, CD34Severity of Illness IndexImmunoenzyme TechniquesPositron-Emission TomographyEnzyme-Linked Immunosorbent AssayUnited StatesDrug Resistance, NeoplasmRecurrenceDiagnostic ImagingUltrasonography