CGRA10: A RARE CASE OF ANTI‐KU ANTIBODIES POSITIVE SYSTEMIC LUPUS ERYTHEMATOSUS AND JUVENILE DERMATOMYOSITIS OVERLAP IN A PAEDIATRIC PATIENT

Abstract

We describe the case of a 14 year old previously healthy girl who presented with fevers, joint and muscle pains, increasing proximal muscle weakness, facial butterfly rash and heliotrope rash of the eyelids for a month. The investigations showed anaemia, thrombocytopenia, low complement C3 and C4 and raised erythrocyte sedimentation rate, lactate dehydrogenase, hepatic transaminases and creatine kinase 6898 U/L (reference range 15–180). The auto-immune screen showed elevated antinuclear antibodies (speckled pattern) >2560 (reference range 0–79), anti-DS DNA antibodies 34 kIU/L (reference range 0–7) and detection of ribonuclear protein, ribosomal P, anti-smith and anti-Ku antibodies. Bone marrow aspirate and C-reactive protein were normal. Magnetic Resonance Imaging (MRI) showed extensive symmetrical truncal and bilateral lower limb muscle oedema. The skin biopsy showed interstitial dermal inflammation with lymphocytes and perivascular inflammation. She was treated with systemic corticosteroids, physiotherapy based on Childhood Myositis Assessment Scale and azathioprine with dramatic improvement. Based on clinical presentation and investigations, a diagnosis of SLE and JDM with overlapping features was made. Our patient is a rare case of anti-Ku antibodies positive SLE and JDM overlap who rapidly responded to immunosuppressive treatment. MRI is a useful diagnostic tool in childhood inflammatory myopathy. Invasive procedures such as muscle biopsy and electromyography are less frequently used in a typical presentation such as our case. Anti-Ku antibodies are rare, with an estimated prevalence of 0.5% of all ANA-positive sera. These antibodies are present in about 2.5 percent of patients with systemic sclerosis in association with myositis and arthritis. Anti-Ku antibodies may also be detected in patients with SLE.