The authors report a case of tumoral calcinosis (TC) in a six-month-old infant, which developed within the thoracotomy scar from previous aortic coarctation repair. After initial resection of the lesion, the child returned with a large mass of TC restricting movement of the left shoulder. Repeated total resection was successful with no recurrence in 12 months' follow-up. This is the first report of TC that developed in a postoperative scar and is unusual in its recurrence and aggressive growth. Pathogenesis, diagnosis and treatment of this rare event is discussed.