OBJECTIVES: The aim of this study was to compare the costs of disease management based on revised diagnoses after centralized histological reviews for sarcoma, GIST, and desmoid tumors with the costs based on diagnoses before reviews. METHODS: A decision tree was constructed. For both options, the initial pathway was the World Health Organization (WHO) Classification of soft tissue and bone tumors. Diagnoses were considered concordant only when the final diagnosis was categorized in the same manner as the initial finding, as defined by the WHO classification. The decision tree was evaluated over a time horizon of 12 months. Disease management and the probabilities were based on a cohort of patients who had a histological review performed within the RRePS (Réseau de Référence en Pathologie des Sarcomes) network in 2010. The characteristics of the patient and disease, as well as any relevant guidelines, were used. All of the disease managements were defined by the authors of this study. The costs were considered from the French National Health Insurance (NHI) perspective and the costs of the histological review were extracted from the literature. The costs were assessed for each pathway and expressed in Euros 2013. The expected costs were calculated. One-way and probabilistic sensitivity analyses were performed.   RESULTS: A total of 2,425 patients underwent a histological review. Of these, 341 patients were found to have a discordant diagnosis. Ten patients were excluded due to missing data. The costs reached €8,420 (histological review included) when disease management was based on revised diagnoses and €8,610 when not. CONCLUSIONS: In addition to the positive impact of centralized histological reviews on the quality of diagnosis for sarcoma, GIST, and desmoid tumors, our model demonstrated that histological reviews lower the cost of disease management for the French NHI.