Osteosarcoma is the most common primary malignant bone tumor in children and adolescents. The standard and most effective treatment is wide resection of the tumor combined with neoadjuvant chemotherapy. Adolescent idiopathic scoliosis (AIS) is a genetically determined three-dimensional spinal deformity, which occurs in teenage patients and is mostly progressive. The basic management strategy is surgical treatment when the curve exceeds 50 degrees. However, the indications are different in oncologic patients. The aim of this study was to describe a case of adolescent scoliosis with osteosarcoma of the pelvis. The authors conducted a scoping review using PubMed and Embase to analyze the state of knowledge. The presented paper is the first report of pelvis osteosarcoma coexisting with adolescent idiopathic scoliosis. Treatment for this complex case finished with very good results, with no recurrence observed during the nine-year follow-up.