Tumoral Calcinosis of the Knee With Secondary Infection in a Patient With Juvenile Dermatomyositis: Management Approach and Pathophysiological and Therapeutic Review.

Tumoral calcinosis is a debilitating complication of juvenile dermatomyositis (JDM) that results from dystrophic calcification in inflamed soft tissues. Although often asymptomatic, it can occasionally be complicated by secondary infections, requiring both medical and surgical interventions. Here, we report a rare case of tumoral calcinosis with superadded infection in a child with JDM, along with a brief pathophysiological and therapeutic overview. An 11-year-old girl with a known history of JDM presented with fever and localized pain in the right knee. Examination revealed local warmth, mild joint restriction, and no other systemic signs. Imaging demonstrated periarticular soft tissue calcifications without osseous involvement. MRI and CT scans confirmed lobulated, calcified soft tissue masses with surrounding edema. The patient underwent surgical incision, drainage, and excision of accessible calcified nodules. Histopathology confirmed tumoral calcinosis with associated inflammation. Postoperative rehabilitation began two weeks after surgery, with favorable functional recovery. Calcinosis in JDM develops through chronic inflammation, metabolic imbalance, and impaired calcium clearance due to dysfunctional macrophages. Contributing factors include genetic susceptibility, immune complex deposition, and mitochondrial injury. Imaging, particularly MRI and CT, is critical for diagnosis and surgical planning. Management requires a multidisciplinary approach, including phosphate restriction, chelation therapy, immunosuppressive agents, and selective surgical excision. Emerging options such as antioxidants, including N-acetylcysteine, have shown promise in slowing disease progression. This case underscores the importance of early recognition and targeted therapy for tumoral calcinosis in JDM. Prompt, coordinated intervention can help prevent irreversible joint damage and improve the quality of life in affected children.