Idiopathic Calcinosis Cutis Universalis in a Child.

Calcinosis cutis is the abnormal deposition of calcium salts in the skin and subcutaneous tissue. In children, it is rare and most often dystrophic, occurring in the setting of an underlying connective tissue disease, with juvenile dermatomyositis being the leading cause. Idiopathic calcinosis cutis universalis, defined by diffuse calcium deposition without preceding tissue damage, metabolic disturbance, or identifiable connective tissue disease, is exceptional in the pediatric population and remains a diagnosis of exclusion. We report the case of a nine-year-old girl with a two-year history of multiple painful subcutaneous calcified lesions that progressively spread over the body and impaired walking. Phosphocalcic balance, parathyroid assessment, and an extensive autoimmune workup, including myositis- and scleroderma-specific antibodies, were unremarkable, and there were no clinical features of dermatomyositis or systemic sclerosis. Whole-body computed tomography showed diffuse periarticular soft tissue calcifications without bone or visceral involvement. A diagnosis of idiopathic calcinosis cutis universalis was made after the exclusion of dystrophic, metabolic, and iatrogenic causes. Management was multimodal and resulted in marked clinical, functional, and radiological improvement, with healing of fistulized lesions and restoration of mobility. This case highlights both the diagnostic rigor required before labeling pediatric calcinosis as idiopathic and the need for prolonged surveillance, as an underlying connective tissue disease may declare itself later.