Abstract
Immunoglobulin G4-related disease (IgG4-RD) is a systemic immune-mediated fibroinflammatory condition characterized by tumefactive lesions that can affect multiple organs. Serum IgG4 levels may be elevated. Early recognition is sometimes difficult but is important to avoid irreversible organ damage. We describe the case of a 28-year-old male patient who presented with a 2-year history of recurrent low-grade fever, night sweats and non-specific manifestations. We eventually diagnosed IgG4-related aortitis by PET-CT scan. The patient was successfully treated with prednisolone and mycophenolate mofetil with complete clinical and radiological resolution. LEARNING POINTS: IgG4-related disease is a systemic immune-mediated disease that can affect many organs and systems.Aortitis can be one of the differential diagnoses in patients with fever of unknown origin, back pain and other unspecific symptoms.Delayed diagnosis and treatment may cause major complications or irreversible damage, so timely diagnosis and appropriate treatment is very important.