Adult and Juvenile Myositis

* ELIGIBILITY CRITERIA: Patients with Myositis: Inclusion Criteria: All patients should have age range 2-100 years. All Patients admitted to the study must satisfy at least one of the following criteria among item 1 (A or B or C) OR item 2 (A or B or C) AND item 3: 1. Patient has documented evidence that he/she meets criteria for an idiopathic inflammatory myopathy A. Possible, probable or definite adult or juvenile polymyositis or dermatomyositis by Bohan and Peter criteria B. Possible, probable or definite inclusion body myositis by Griggs and/or ENMC criteria C. Has an idiopathic inflammatory myopathy that does not meet these criteria, including common or rarer forms of myositis such as cancer- associated, focal, orbital, eosinophilic myositis, macrophagic, proliferative, etc. 2. Has one of the following conditions: 2A. Have a disorder that is related to an idiopathic inflammatory myopathy, that may include: * Inflammatory and non-inflammatory myopathies: * Mimicking and related skin disorders: * Disorders of the complications of myositis (including interstitial lung disease, calcifying disorders, cardiomyopathies, etc.): * Overlapping autoimmune diseases that may be associated with myositis * Patients with muscle and/or skin inflammation and documented environmental exposures: * Patients with myositis or complications of myositis and suspected genetic disorders: * Patients with undifferentiated connective tissue disease * Patients with signs or symptoms of myositis (such as weakness, skin rashes, interstitial lung disease) or laboratory abnormalities (such as elevated CK or muscle biopsy with myopathic features) who do not have an established diagnosis of myositis for them to be evaluated to establish a diagnosis 3\. Ability of patient or parent/guardian to give informed consent to all or part of the study after full information has been provided. Exclusion Criteria: 1. Patients \<2 years or \>100 years will be excluded. 2. Any conditions in which the drawing of the amount of blood required or undergoing procedures needed for the study is not deemed medically appropriate by the treating physician or the principal investigator. For females of childbearing potential who are pregnant, they will be permitted to enroll, but would be excluded from radiographic procedures involving radiation or greater than minimal risk procedures, including obtaining biopsies. Relatives of Patients with Myositis: For patients with at least one first-degree relative affected with IIIM, all available first-degree relatives (affected and unaffected) are eligible to participate in the genetics portion of the protocol. For patients in which two or more first degree relatives are affected with myositis, any available close relatives (affected or unaffected parents, siblings or children, as well as grandparents and grandchildren, or other close relatives, when available) are eligible to participate in the genetics portion of the protocol. Inclusion criteria: 1. First or more distant relative of a proband with myositis, for genetics studies. 2. Ability of patient or parent/guardian to give informed consent to all or part of the study after full information has been provided. Exclusion Criteria: 1. Patients \<2 years or \>100 years will be excluded. 2. Any conditions in which the drawing of the amount of blood required or undergoing procedures needed for the study is not deemed medically appropriate by the treating physician or the principal investigator. 3. Pregnancy (females of childbearing potential). Verbal confirmation they are not pregnant. Healthy Volunteers: Inclusion Criteria: 1. Healthy volunteer subjects for biomarker studies will be gender and age-matched (within 5 years) with a myositis patient, as reasonably close as possible. 2. Volunteer is not related to a myositis patient who is enrolled in the study 3. Volunteer is in good health, without a recognized systemic rheumatic disorder, autoimmune disease, immune medicated disease, or cancer, and is not taking any anti-inflammatory medicines, including nonsteroidal anti-inflammatory drugs (NSAIDS) or corticosteroids 4. Volunteer or volunteer s parent/guardian could give assent/informed consent to all or part of the study after full information has been provided Exclusion Criteria: If Any "Yes" answer patient is not eligible for study 1. Volunteer has undergone surgery or had a major trauma within the past 2 months 2. Volunteer used anti-inflammatory medications within the past 8 weeks of enrollment, including not currently receiving nonsteroidal anti-inflammatory drugs or corticosteroids 3. Volunteer has been diagnosed with a chronic infectious illness, inflammatory disease, malignancy, cardiac or pulmonary disease, muscle disorder, clotting disorder, metabolic disorder, systemic rheumatic or autoimmune disease, or immune-mediated disease 4. Volunteer is pregnant (verbally screened for females of childbearing potential) 5. Volunteer has a medical illness that in the judgement of the investigators does not allow safe blood draws or other clinical evaluations needed for study participation 6. Volunteer is cognitively impaired 7. Volunteer and or the volunteer's parents/legal guardian is unable or unwilling to give informed consent/assent 8. Volunteer has functional limitations 9. Volunteer has joint or muscle problems In IMAGE Survey participants must confirm in the survey that they have a medical diagnosis of myositis. Note that the following screening activities may be performed to determine subject eligibility: * Email, written, or telephone communications with prospective subjects * Review of existing medical records * Review of existing imaging studies * Review of existing photographs or videos * Review of existing pathology specimens/reports from a specimen obtained for diagnostic purposes If a participant is ineligible and willing, their contact information- including name, phone numbers, emails, best times to reach, and potential diagnosis- may be shared with other NIH investigators if the participant may be eligible to participate in those studies.