LiposarcomaLiposarcoma, MyxoidRNA-Binding Protein FUSRetroperitoneal NeoplasmsNeoplasms, Adipose TissueLipomaSoft Tissue NeoplasmsTomography, X-Ray ComputedSensitivity and SpecificityDelayed DiagnosisPrenatal DiagnosisMuscle NeoplasmsEarly DiagnosisMagnetic Resonance ImagingSarcomaTranscription Factor CHOPFatal OutcomeBiopsyRetrospective StudiesSpermatic CordGenital Neoplasms, MaleChromosomes, Human, Pair 12ImmunohistochemistryMediastinal NeoplasmsDiagnosisDiagnostic ErrorsLeiomyosarcomaTreatment OutcomeMesocolonTumor Markers, BiologicalPredictive Value of TestsDioxolesHistiocytoma, Malignant FibrousCell DedifferentiationPrognosisTime FactorsHistiocytoma, Benign FibrousThighTetrahydroisoquinolinesDiagnosis, Computer-AssistedBiopsy, NeedleProto-Oncogene Proteins c-mdm2Polymerase Chain ReactionAbdominal NeoplasmsOncogene Proteins, FusionReproducibility of ResultsFollow-Up StudiesProspective StudiesFibromaPeritoneal Neoplasms