"Aneurysmal Bone Cyst of the Pelvis: A Systematic Literature Review"

Abstract

Background:Aneurysmal bone cysts (ABC) are rare benign, vascular, osteolytic bone lesions. Pelvic ABCs account for 8 -12% of these tumors and no clear guidelines for their treatment are available. To our knowledge, this is the first systematic literature review regarding pelvic ABCs. Our primary objective was to identify treatment modalities and to assess the bone healing, measured as the degree of radiological ossification. Secondary objectives were to describe demographics, tumor characteristics, clinical and functional outcomes and recurrence.Methods: Searches were conducted in PubMed, Cochrane Library, and Web of Science. Based on the scarcity of reports, inclusion criteria were kept broad and comprised primary or recurrent pelvic ABCs, with a minimum follow up of one year and available information on radiological ossification. Data was extracted on the individual patient-level and grouped according to treatment modality. Results:Forty-nine studies reporting on 194 patients were included. The level of evidence was low (29 case reports and 20 retrospective case series) and the reporting of outcomes inconsistent. Patients had a median age of 15 years and 52% were male. Five major treatment groups were identified and divided into 11 subgroups. The largest subgroup was curettage (23%) followed by selective arterial embolization (20%). Most ABCs were located in the ilium. Variations in mean tumor size (4.5-22.2cm) and degree of ossification (60-100%) depended on the treatment modality. Overall, in 77% cases the cyst ossified completely. Recurrence was reported in 22 patients (11%) and 2 patients (1%) died during the course of the treatment.Conclusion:Despite the low quality of reporting, this systematic review provides the first comprehensive overview of pelvic ABC treatment modalities and their radiological and clinical outcomes. Neoadjuvant sclero-embolic treatments appear to be used most in recent years, but further comparative studies and better quality of reporting are needed to determine their effectiveness. Quality of reporting should be improved by following reporting guidelines.Level of Evidence: IV