Carcinoma, Signet Ring CellAdenocarcinoma, MucinousStomach NeoplasmsAppendiceal NeoplasmsUmbilicusCarcinomaAdenocarcinomaImmunohistochemistryMicrosatellite InstabilityGastrectomyRare DiseasesMucinsNeoplasms, Unknown PrimaryProto-Oncogene Proteins B-rafPeritoneal NeoplasmsCadherinsCarcinoma, Squamous CellNeoplasm MetastasisPyloric AntrumCarcinoma, HepatocellularEndoscopy, GastrointestinalNeoplasm StagingColorectal NeoplasmsNeoplasm Invasivenessras ProteinsLoss of HeterozygosityPrognosisHistocytochemistryAlcian BlueMicrosatellite RepeatsTumor Markers, Biological