title: How to investigate multisystem disease.
abstract: The investigation of the patient with possible systemic autoimmune rheumatic disease is potentially one of the most challenging areas of rheumatology as the differential diagnosis is potentially very broad. The investigative approach should not only be directed at confirming the diagnosis of an autoimmune rheumatic disease but also at excluding as best as possible the major alternative diagnoses of malignancy and infection. A systematic approach should yield a positive diagnosis in the majority of cases based on excluding infection by appropriate cultures and serology, malignancy using imaging including 18-fluorodeoxyglucose positron emission tomography/computerized tomography (FDG PET/CT). The most important part of the assessment is the history, in particular covering systems that may not previously been assessed such as ears, nose, throat or eyes. The clue to the diagnosis of an autoimmune rheumatic disease often lies in detecting the multisystem nature of the condition and the cumulative effects of multiorgan involvement. Investigation may therefore need to cover different systems. Although stratified approaches have been described, they have not been subjected to a detailed investigation as to their effectiveness.
authors.affiliation: Ipswich Hospital NHS Trust, UK; Norwich Medical School, Norwich, UK. Electronic address: Richard.watts@ipswichhospital.nhs.uk.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Watts
mesh_terms: D001327:Autoimmune Diseases / Q000175:diagnosis*; D003937:Diagnosis, Differential; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage; D006801:Humans; D009369:Neoplasms / Q000175:diagnosis; D049268:Positron-Emission Tomography / Q000379:methods; D012216:Rheumatic Diseases / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: Autoimmune rheumatic disease; Investigation autoantibodies; PET/CT; pyrexia of unknown origin (PUO)