Takayasu's arteritis in an adolescent with fever of unknown origin: the contribution of PET-CT in the diagnosis.

Finding the cause of fever of unknown origin can sometimes be a real challenge. We present an adolescent whose diagnosis was achieved after 4 months of fever onset by performing a positron emission tomography (PET)-CT. A young woman presented with prolonged, intermittent fever along with inflammatory and iron deficiency anaemia, loss of weight and abdominal and chest pain. First investigational studies showed high-titre positive antinuclear antibodies, extractable nuclear antibodies and anti-Sjögren's-syndrome-related antigen a autoantibodies (anti-SSA), and mild pericardial effusion and aortic regurgitation, but without meeting criteria for systemic lupus erythematosus. She had maxillary sinusitis that did not resolve with antibiotics. Further study displayed elevated calprotectin in faeces. After normal abdominal ultrasound and CT, an intestinal MRI showed thickening of the terminal ileum, orienting towards an inflammatory bowel disease. A colonoscopy showed only minor macroscopic changes. A PET-CT scan was finally requested, which exhibited a diffuse increase in metabolism in the wall of the thoracic and abdominal aortas, suggesting Takayasu's arteritis.