Calcinosis Cutis as the Leading Manifestation of Juvenile Dermatomyositis: A Case Report.

Introduction: Juvenile dermatomyositis (JDM) is a rare autoimmune inflammatory myopathy of childhood. Initial manifestations may be atypical and lead to delays in diagnosis. Case report: An 11-year-old boy with a history of trauma of the left knee was initially treated with systemic antibiotics without clinical improvement. On physical examination, ulcerated plaques composed of multiple fistulous tracts with abundant purulent discharge were observed. A skin biopsy revealed findings consistent with calcinosis cutis. The autoantibody panel was positive for anti-Mi-2 antibodies, along with elevated muscle enzymes (CK = 2892 U/L). A diagnosis of JDM was established, and systemic treatment with prednisone at 1 mg/kg/day was initiated, resulting in an adequate clinical response of the lesions. Conclusion: JDM is a rare condition with a variable clinical presentation in the pediatric population. This case highlights the importance of considering JDM in the differential diagnosis of patients presenting with calcinosis, even in the absence of classic cutaneous manifestations and with only subtle or initially unrecognized muscle involvement.