SEEING THROUGH SKIN: HOW ADVANCED MRI TRANSFORMS DERMATOMYOSITIS DIAGNOSIS

Juvenile dermatomyositis (JDM) is a rare systemic autoimmune connective tissue disorder marked by distinctive cutaneous manifestations and progressive proximal muscle weakness. While the Bohan and Peter criteria historically guided diagnosis, magnetic resonance imaging (MRI) has emerged as a non-invasive alternative that is increasingly supplanting muscle biopsy for both confirmation and ongoing monitoring of JDM. Three pediatric patients, aged 4 to 8 years, presented with characteristic cutaneous findings and muscle weakness and underwent whole-body MRI (WBMRI). These cases were selected for their representative clinical features and the diagnostic complexity associated with juvenile dermatomyositis (JDM). Each patient exhibited distinct clinical manifestations, all confirmed by established JDM diagnostic criteria. American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) scores ranged from 7 to 9, reflecting the variability and severity of symptoms in pediatric populations. WBMRI with short tau inversion recovery (STIR) sequences enabled comprehensive assessment, revealing symmetric muscle involvement with T2/STIR hyperintensity in proximal muscles, subcutaneous fat reticulation, and fascial involvement. One patient demonstrated large calcifications on WBMRI, while the other cases showed diffuse inflammation and perivascular enhancement in the pelvis and thighs. WBMRI findings correlated with clinical severity, elevated muscle enzyme levels, and positive autoimmune markers, underscoring its value as a non-invasive diagnostic modality. In summary, WBMRI is an essential non-invasive modality for diagnosing juvenile dermatomyositis (JDM). Early detection of subclinical involvement enables objective assessment of disease activity, facilitating timely diagnosis and effective treatment strategies. This approach contributes to improved long-term patient outcomes.