An 11-year-old girl presenting with neck pain was diagnosed as having an aneurysmal bone cyst involving the posterior arch of C1. Minimally invasive treatment was performed with percutaneous injections of calcitonin and methylprednisolone. Two injections separated in time by 2 months were performed with complete sclerosis and ossification of the cyst over a period of 6 months. Such percutaneous sclerosis offers an important primary therapeutic option or an adjunct to surgery of these otherwise vascular cystic masses and should be contemplated as the initial step in the treatment of these benign tumors, especially those in the spine where surgical treatment can involve complex resection and fixation procedures.