HLA-B27-negative sacroiliitis: a manifestation of familial Mediterranean fever in childhood.

Familial Mediterranean fever is a polysystemic disease seen most frequently in persons of Mediterranean ancestry. Arthritis is one of the common manifestations. Both symptomatic and asymptomatic sacroiliitis have been reported in adults. We report on two children with familial Mediterranean fever with radiographic abnormalities similar to those described in adults. Although sacroiliitis is strongly correlated with the presence of HLA-B27 in most arthropathies, these children were HLA-B27-negative. The diagnosis of familial Mediterranean fever was delayed in both patients because the association of sacroiliitis with familial Mediterranean fever in childhood was not recognized.