This book reflects the experience of the Rizzoli Orthopedic Institute during more than 100 years of treatment of musculoskeletal tumor and tumorlike lesions. It presents a wide range of lesions from a multidisciplinary perspective, highlighting pertinent clinical, radiological, and histological correlations. Treatment is briefly reported for each entity. In addition, the more recent biomolecular findings of use for diagnosis, prognosis, and treatment are carefully analyzed. The Rizzoli case archive spans more than a century, the first treated case dating back to 28 September 1900, and contains the original material – clinical charts, imaging, paraffin blocks, and histological slides – of more than 40,000 cases, including about 29,000 bone lesions and 11,000 soft tissue lesions. This book reports the most relevant entities and reflects the improvements in knowledge of musculoskeletal tumors as presented during the yearly international course held at the Rizzoli Institute.​