DermatomyositisPolymyositisMyositisParaneoplastic SyndromesLung Diseases, InterstitialMediastinal EmphysemaPanniculitisMuscle WeaknessHistidine-tRNA LigaseAutoantibodiesBiopsyPrednisoloneLupus Erythematosus, CutaneousRheumatic DiseasesMuscle, SkeletalMyositis, Inclusion BodyRetrospective StudiesImmunosuppressive AgentsImmunoglobulins, IntravenousConnective Tissue DiseasesSkinTelangiectasisMicroscopic AngioscopySeverity of Illness IndexCreatine Kinase