Large-vessel vasculitis in Behçet’s disease carrying MEFV exon 10 variants: a case suggesting a pyrin-associated autoinflammatory background

Behçet's disease (BD) is a multisystem inflammatory disorder in which innate immune dysregulation has been increasingly recognized as a key pathogenic feature, and MEFV variants have also been implicated in its pathogenesis. We describe the case of a 51-year-old Japanese woman with incomplete BD who developed large-vessel vasculitis during treatment with low-dose glucocorticoids and colchicine. She had a history of recurrent abdominal pain associated with menstruation and two episodes of aseptic meningitis since childhood, but she had never experienced periodic fever. Genetic analysis revealed compound heterozygous MEFV variants (E148Q in exon 2 and M694I in exon 10). 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) demonstrated aneurysms of the brachiocephalic and bilateral subclavian arteries with patchy FDG uptake, indicating active vasculitis consistent with BD rather than familial Mediterranean fever (FMF). Infliximab therapy was initiated for BD-associated vasculitis, resulting in rapid normalization of CRP and successful tapering of prednisolone. This case suggests that MEFV variants may contribute to an autoinflammatory background predisposing to vascular involvement in BD even in the absence of clinical FMF. The association between MEFV variants and vascular involvement in BD remains controversial, and it has not been consistently demonstrated in Japanese populations, where both the clinical features and genetic background of FMF differ from those of Eastern Mediterranean patients. This case may therefore provide further insight into the role of MEFV variants in the pathogenesis of vascular involvement in BD, particularly in Japanese patients.