Successful treatment with tocilizumab in a case of familial Mediterranean fever with Takayasu arteritis.

Familial Mediterranean fever (FMF) is an autoinflammatory disease associated with mutations in MEFV, which encodes pyrin. Patients with FMF present intermittent high fever with elevated inflammatory markers during periodic attacks. While some forms of vasculitis, including immunoglobulin A (IgA) vasculitis and polyarteritis nodosa have been reported in some patients with FMF, Takayasu arteritis (TAK) rarely associated with FMF. In addition, little has been known about the clinical features and pathogenesis of vasculitis with FMF. Here we report a case of FMF with TAK. Our case is remarkable on his clinical course of neck pain with low-grade elevation of serum C-reactive protein during interictal periods of fever attacks. He possessed the dual genetic background of a pathogenic variant of p.M694V in MEFV and HLA-B*52:01, which is susceptible to TAK. Although he was refractory to the combination therapy with colchicine, corticosteroids, and methotrexate, tocilizumab was effective for both recurrent fever attacks and vasculitis. Previous four reports of FMF with TAK as well as our case suggest the pathogenic MEFV mutation could be a predisposing or additional factor that modify the development of TAK. Since both the activity of FMF and TAK responded to tocilizumab in our case, the pathogenesis shared between FMF and TAK was indicated.