This book, now in a second revised edition, casts light on the often complex diagnosis of musculoskeletal tumors and tumor-like conditions by drawing on the experience of the Rizzoli Orthopedic Institute during more than 100 years of treatment and research in the field. The different entities are described from a multidisciplinary perspective, highlighting clinical, radiological, and histological correlations. Particular emphasis is placed on differential diagnosis, which often needs to take into account nontumoral conditions. The recent identification of further significant biological and genetic features, and the impact of these discoveries on the classification of round cell tumors, vascular lesions, and spindle/pleomorphic entities in bone, is also extensively discussed. The Rizzoli case archive dates back to September 1900 and contains the original material relating to more than 29,000 bone lesions and 11,000 soft tissue lesions. It is a fabulously rich resource, and this book will be invaluable for pathologists, radiologists, and clinicians at all levels of experience.