title: Anti-MDA5-Positive Dermatomyositis Presenting as Fever of Unknown Origin.
abstract: Dermatomyositis is a chronic systemic autoimmune disease characterized by inflammatory infiltrates in the skin and muscle. The wide variability in clinical and serologic presentation poses a diagnostic challenge for the internist. Appreciation of the clinical variants of dermatomyositis allows for expedient diagnosis and avoidance of diagnostic error. We illustrate these challenges with the case of a 51-year-old Vietnamese-American man who initially presented with fever of unknown origin in the absence of overt skin and muscle manifestations. The diagnosis of dermatomyositis was not evident on several clinical encounters due to the absence of these hallmark symptoms. We review the variable clinical manifestations of a subtype of dermatomyositis associated with an autoantibody against melanoma differentiation-associated protein 5 (anti-MDA5) and suggest consideration of dermatomyositis as a diagnosis in patients presenting with systemic illness and markedly elevated ferritin, even in the absence of elevated muscle enzymes and classic autoantibodies.
authors.affiliation: Stanford University School of Medicine, Stanford, CA, USA. lwhlee@stanford.edu.
authors.forename: Lori W
authors.initials: LW
authors.lastname: Lee
authors.affiliation: Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Neera S
authors.initials: NS
authors.lastname: Narang
authors.affiliation: Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Postolova
authors.affiliation: Department of Dermatology, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: Seminara
authors.affiliation: Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.|Department of Medicine, Division of Hospital Medicine, University of California, San Diego, School of Medicine, San Diego, CA, USA.
authors.forename: Molly A
authors.initials: MA
authors.lastname: Kantor
mesh_terms: D003882:Dermatomyositis / Q000097:blood* / Q000150:complications / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D005335:Fever of Unknown Origin / Q000097:blood* / Q000150:complications / Q000000981:diagnostic imaging*; D006801:Humans; D000072640:Interferon-Induced Helicase, IFIH1 / Q000097:blood*; D008297:Male; D008875:Middle Aged
chemical_list: C452815:IFIH1 protein, human; D000072640:Interferon-Induced Helicase, IFIH1
keywords: case report; clinical evaluation; clinical reasoning; clinical vignette; dermatomyositis; diagnosis; errors in clinical reasoning; evaluation; fever of unknown origin; rheumatology