[Bartonella henselae myositis: case report in an adolescent].

Infectious myositis, whether viral or bacterial, is frequent in pediatric age. It causes muscle pain and weakness, associated with fever and general malaise. One cause is Bartonella henselae, responsible for cat scratch disease, which sometimes causes systemic symptoms. We report the case of an adolescent who came to the emergency room with intense myalgia, malaise, weight loss and splenomegaly. Blood tests showed high inflammatory markers. She had been in touch with a cat. Studies were carried out including: lower limbs MRI suggestive of bilateral inflammatory myositis, abdominal MRI with three previously undetected splenic lesions and dilated fundus examination that showed possible retinal arterial occlusion or vasculitis. After 21 days of intravenous antibiotic therapy (cefotaxime + cloxaciline), she became asymptomatic, but inflammatory markers remained high. Suspecting Bartonella henselae infection (myositis + chorioretinitis + splenic abscess), oral azithromycin and rifampicin were prescribed for 14 days. Blood tests and control MRI became normal, and IgG was positive.