DermatomyositisPolymyositisMyositisMyositis, Inclusion BodyLung Diseases, InterstitialHistidine-tRNA LigaseParaneoplastic SyndromesOrbital MyositisAutoantibodiesMuscle WeaknessNervous System Autoimmune Disease, ExperimentalMuscle, SkeletalMediastinal EmphysemaPrednisoloneMuscular DiseasesCreatine KinaseConnective Tissue DiseasesBiopsyImmunosuppressive AgentsAutoimmune DiseasesMusclesImmunoglobulins, IntravenousScleroderma, SystemicAdrenal Cortex HormonesRheumatic DiseasesAntibodies, AntinuclearOrbital PseudotumorMixed Connective Tissue DiseasePanniculitisAutoantigensFatal OutcomeLactate DehydrogenasesLupus Erythematosus, CutaneousMacroglossiaAzathioprinePlasmapheresisSeverity of Illness IndexGlucocorticoidsRetrospective Studies