Misty Mesentery as an Initial Imaging Finding Suggestive of Large Vessel Vasculitis.

Large vessel vasculitis (LVV) refers to vasculitis predominantly affecting large arteries, including the aorta and its major branches. It encompasses conditions such as giant cell arteritis and Takayasu arteritis, as well as unclassified or idiopathic forms. Imaging techniques, including computed tomography (CT), are essential for detecting large vessel involvement, particularly when biopsy findings are negative. We report the case of a 56-year-old man admitted with fever, headache, and upper abdominal pain lasting 2 weeks. On examination, he had scalp tenderness and upper abdominal tenderness without temporal artery enlargement. Laboratory tests revealed elevated C-reactive protein (CRP: 19.75 mg/dL) and normal IgG4 (45 mg/dL). Initial CT demonstrated increased attenuation of mesenteric fat (Figure 1), suggestive of misty mesentery. Antibiotic therapy for presumed infectious mesenteritis was ineffective, and CRP increased further to 30.20 mg/dL. Contrast-enhanced CT showed thickening of the aortic wall (Figure 2). Based on fever, headache, systemic inflammation, and aortic wall thickening, LVV was considered the most plausible diagnosis. Cite this article as: Noda S, Kondo S. Misty mesentery as an initial imaging finding suggestive of large vessel vasculitis. Eur J Rheumatol. 13(1), 0084, doi: 10.5152/eurjrheum.2026.25084.