Inclusion Criteria:  Male and female patients treated at Rizzoli Institute from 01 Jan 1993 to 01 Dec 2017 Diagnosis of mixofibrosarcoma of extremities Histological slides/formalin-fixed paraffin-embedded tissue tumor (FFPE) blocks from archive available to perform the histology analysis and molecular analysis Enough tumor biobanked material available for molecular analysis Presence of the biobank signed informed consent Written informed consent prior to any study-specific analysis and/or data collection  Exclusion Criteria:  1) Patients with histological diagnosis different from mixofibrosarcoma of extremities