Risk factors for developing calcinosis in juvenile dermatomyositis: subcutaneous and myofascial edema in initial magnetic resonance imaging

Calcinosis is a sequela of Juvenile Dermatomyositis (JDM) with significant morbidity. A retrospective study observing risk factors for JDM calcinosis, including a possible association between higher intensity of subcutaneous and myofascial edema in initial magnetic resonance imaging (MRI) and development of calcinosis was performed at a tertiary pediatric medical center. Data from the past 20 years on JDM patients with MRIs at the time of JDM diagnosis were obtained. MRIs were individually evaluated by two pediatric musculoskeletal radiologists who blindly graded the intensity of edema on a 0–4 Likert scale. Clinical data and edema scores were compared between patients who developed calcinosis and who did not. Forty-three patients (14 with calcinosis and 29 without calcinosis) were identified. The calcinosis group contained more racial and ethnic minorities, younger ages of JDM onset and longer time to reach JDM diagnosis. Muscle enzyme levels at JDM diagnosis were lower in the calcinosis group, especially Creatinine Kinase (CK) (p = 0.047) and Alanine Aminotransferase (ALT) (p = 0.015). The median score for edema in both groups was 3 (p = 0.39) with an inter-rater reliability of 95%. There was no association between increased subcutaneous and myofascial edema in MRIs at the time of JDM diagnosis and development of calcinosis. Earlier age of JDM onset, racial and ethnic minority, and delay in JDM diagnosis could be risks for developing calcinosis. The calcinosis group presented with lower muscle enzyme levels at the time of JDM diagnosis, especially CK and ALT with statistical significance. This could reflect delay in diagnosis and treatment.