Sacroiliitis in familial Mediterranean fever and seronegative spondyloarthropathy: importance of differential diagnosis.

Familial Mediterranean fever (FMF) is a multisystemic autosomal recessive disease, occasionally accompanied by sacroiliitis. Transient and non-erosive arthritis of the large joints is the most frequent articular involvement. Amyloidosis is also the most significant complication of FMF, leading to end stage renal disease. Here we present three cases of FMF with sacroiliitis and review the literature for spinal arthritic involvement of FMF. All cases were referred to our clinic with a diagnosis of seronegative spondyloarthropathy and with low back pain sourced by sacroiliitis. They also had homozygous M694V gene mutations and negative HLA B27 antigens. Molecular analysis of the gene mutation is recommended during the evaluation of uncertain cases in order to clarify diagnostic discrimination. We suggest that FMF with sacroiliitis, which is rare in rheumatological practice, should be considered in the differential diagnosis of seronegative spondyloarthropathy or other rheumatologic diseases causing spinal involvement.