Sacroiliitis in familial Mediterranean fever: an unusual presentation in childhood.

Familial Mediterranean fever (FMF) is an autosomal recessively transmitted disease characterized by attacks of fever and serositis. The course of arthritis, which is a common manifestation of FMF, is generally benign. Sacroiliitis due to FMF has been reported by several authors, but all the patients described so far had roentgenographic abnormalities, and most of them were adult cases. Here we report the youngest FMF patient with sacroiliitis without any abnormality on sacroiliac x-ray. She is also the first FMF patient in whom sacroiliac involvement was diagnosed by computed tomography (CT) in childhood. It is concluded that CT is a useful technique for the early diagnosis of destructive arthritis in FMF patients even in early childhood.