Deutscher Rheumatologiekongress 2026
Sudden severe muscle weakness in a nine-year-old girl
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History: The previous history was blank except for two seizures, no pharmacological treatment was required. The patient has been living with a foster family since she was 10-month-old.
Cardinal symptom by manifestation of disease: A 9-year-old female presented herself with persistent soreness in her limbs. The patient reported having trouble climbing stairs and changing her clothes due to difficulty raising her arms. The physical examination revealed severe muscle weakness without skin involvement. Strength and reflexes in the upper extremities were diminished.
Diagnostics: Laboratory tests revealed elevated levels of Aspartate Aminotransferase 871 U/l, Alanine Aminotransferase 498 U/l, Creatine Kinase (CK) 19,619 U/l, CK-MB 2,052 U/l, Troponin T 5,487 pg/ml and Antinuclear Antibody (ANA) test 1:5,200 (positive: SS-A/Ro-52/Nucleosomen). The childhood myositis assessment scale (CMAS) was 3/52. Whole-body magnetic resonance imaging (MRI) demonstrated proximal muscle inflammation. A muscle biopsy showed signs of necrotizing myositis. Testing for myositis antibodies confirmed the presence of anti-signal recognition particle (anti-SRP). Further examinations including an electrocardiogram, echocardiography, diagnostics for infectious disease, electroencephalogram, MRI of the brain and computed tomography of the chest revealed no abnormalities.
Therapy: Immune modulated therapy (IMT) was administered [1]. Therapy included pulsed methylprednisolone in combination with intravenous immunoglobulin, methotrexate, mycophenolate mofetil, cyclophosphamide, rituximab and abatacept. IMT was accompanied by daily intensive physical therapy. Despite CK-level improvement, IMT failed to significantly improve muscle strength measured by weekly CMAS scores. CMAS level did not exceed 10/52. Thus, an immunoablation followed by an autologous stem cell transplant (ASCT) was considered and performed. An intensive rehabilitation was started promptly afterwards.
Further course: Four weeks after ASCT a successful decline in disease activity was observed. The patient was walking with little support. Muscle strength continued to increase steadily. Full muscle strength was achieved one year after ASCT. ASCT induced the remission of the disease.
Detection of anti-SRP led to the diagnosis of immune-mediated necrotizing myopathy (IMNM). IMNM is characterized by proximal muscle weakness and elevated levels of serum muscle enzymes. Anti-SRP associated myopathy is rare in children and often fails to respond to standard immunosuppression. Our case adds to the growing literature of ASCT in children with inflammatory myopathies.
Disclosures: JB: None declared.
