Anti-Ku-antibody Positive Juvenile Dermatomyositis in a Young Boy
Ayan Chaudhuri, Ritasman Baisya, Aditi Das, Rohit Bhowmick, Abanti DasAbstract
Background:
Juvenile dermatomyositis (JDM) is a rare inflammatory myositis with associated cutaneous manifestations. Anti-Ku antibodies are a myositis-associated autoantibody that may rarely be seen in JDM. Very few reports of anti-Ku-antibody-positive JDM in children have been published.
Clinical Description:
A 3-year-old boy presented with periorbital puffiness and a hyperpigmented facial rash for one year, as well as rash over the chest, bilateral elbows, and knees, along with progressive symmetric lower-limb weakness for the past few months. Examination revealed a hyperpigmented rash on the face, chest, back, and bilateral elbows and knees, with characteristic Gottron’s papules, and bilateral weakness of hip flexors.
Management and Outcome:
Laboratory investigations showed a normal leukocyte count and inflammatory markers, and normal muscle enzymes, including creatine kinase. Magnetic resonance imaging showed myofasciitis of the bilateral gluteal region and bilateral thigh muscles. Antibody analysis revealed positivity for anti-Ku antibody. At the time of diagnosis, his EULAR/ACR score was 5.1. Thus diagnosed as JDM with anti-Ku antibody positivity, the child was treated with oral prednisone, weekly methotrexate, and sun protection. Follow-up showed gradual rash resolution and improvement in weakness.
Conclusion:
This rare pediatric case of anti-Ku-positive JDM featured proximal weakness and skin involvement, with normal enzymes, responding well to standard immunosuppression therapy.