Calcinosis Cutis and Delayed-Onset Myositis in a Case of Suspected Localized Scleroderma: A Diagnostic and Therapeutic Challenge.

A 16-year-old girl presenting with calcinosis cutis and localized scleroderma subsequently developed delayed-onset idiopathic inflammatory myopathy five years after initial skin involvement. Despite the absence of typical dermatomyositis features and negative myositis-specific antibodies, whole-body MRI revealed extensive subclinical muscle inflammation. This rare clinical evolution highlights the importance of long-term surveillance in pediatric autoimmune disease and supports the role of imaging in detecting early, atypical manifestations of inflammatory myopathy.