Magnetic resonance findings may aid in diagnosis of protracted febrile myalgia syndrome: a retrospective, multicenter study

Abstract

Background: Protracted febrile myalgia syndrome (PFMS) is a rare complication of Familial Mediterranean fever (FMF). The diagnosis is based on clinical symptoms and is often challenging, especially when PFMS is the initial manifestation of FMF. The aim of this report was to describe the magnetic resonance imaging (MRI) findings in pediatric patients with PFMS.

Results: There were three girls and two boys ranging in age from 6 months to 16 years, all of Mediterranean ancestry. Three had high-grade fever, and all had elevated inflammatory markers. MRI of the extremities yielded findings suggestive of myositis, which together with the clinical picture, normal CPK levels, and supporting family history of FMF, suggested the diagnosis of PFMS. Out of most common MEFV mutations tested, one patient was homozygous for M694V mutation, three were heterozygous for M694V mutation, and one was compound heterozygous for the M694V and V726A mutations.

Conclusions: MRI may serve as an auxiliary diagnostic tool in PFMS.

Keywords: Familial Mediterranean fever; M694V; Magnetic resonance imaging; Myositis; Protracted febrile myalgia syndrome.

Fig. 1

MRI of the right arm, (Images 1.1, 1.2) of patient number 1, demonstrates a high T2FS signal (along Triceps, Biceps and Brachialis) compatible with myositis.

Fig. 2

MRI of the legs (Images 2.1, 2.2, 2.3), patient number 2, shows a high signal on T2-weighted images with calf muscle enhancement after gadolinium injection compatible with myositis. The bone marrow signal is normal

Fig. 3

MRI of the lower limbs (Images 3.1, 3.2, 3.3, 3.4) of patient number 3, reveals extensive edema involving the muscles without fat atrophy, compatible with myositis