Introduction-Screening for auto-antibodies(Abs) is useful for the management of idiopathic inflammatory myopathies(IIMs). Among myositis-specific Abs(MSA), some Abs are reported to be associated with juvenile variants. Our aim was to determine the frequency and clinical relevance of MSA in children. Methods-During a period of 10 years, 392 serum samples were tested for a suspicion of IIM. MSA screening was done using immunodot. We included in this study pediatric cases with positive MSA. Results-Among 129 positive tests for at least one MSA, 3 pediatric cases were enrolled. These patients (three boys; mean age: 8 years) had in common walking difficulties. Disease-onset was insidious in one case and subacute with a preceding infectious episode in 2 cases. The diagnosis of IIM was reached in one patient with positive anti-NXP2 Abs, a clinical myopathic syndrome, electromyographical abnormalities and suggestive histological features. The IIM diagnosis was probable in another case taking into consideration the clinical and electromyographical features, the inflammatory biological syndrome and the positivity of anti-TIF1gamma but without a histological confirmation. For the third case (positive anti-MDA5 Abs), electroneuromyography showed an acute motor axonal neuropathy pattern; cerebro-spinal fluid analysis showed an albumino-cytological dissociation. The association of an acute polyradiculoneuropathy with a muscular disorder remained to be confirmed. Conclusion-Our results are in accordance with literature data regarding the low seroprevalence of MSA in children and the antigenic specificities reported in this population. The positivity of these Abs enables to evoke juvenile variants of IIM, which diagnosis relays on clinical, biological, electromyographical and histological arguments.

Sabrina Mejdoub
Habib Bourguiba University Hospital
Tunisia

Salma Mallouli
Hedi Chaker University Hospital
Tunisia

Hend Hachicha
Habib Bourguiba University Hospital
Tunisia

Fatma Kammoun
Hedi Chaker University Hospital
Tunisia

Sawsan Feki
Habib Bourguiba University Hospital
Tunisia

Chahnez Triki
Hedi Chaker University Hospital
Tunisia

Hatem Masmoudi
Habib Bourguiba University Hospital
Tunisia