This book is focused on mastering basic skills and concepts to tackle some of the most difficult lesions encountered in diagnostic surgical pathology. This volume is concise, rich in high quality images, and intended to either offer a foundation or a refresher course in soft tissue lesions. In it, we have taken a novel approach, dividing the book into a brief introductory section that points out some basic principles of reviewing mesenchymal lesions, and then we delve into tumors that can be diagnosed on routine hematoxylin and eosin only – in fact, the majority of soft tissue lesions – together with some for which ancillary studies are helpful. We end with a discussion of lesions for which performing ancillary studies can be important. This book encourages taking diagnoses as far as possible by honing our foundational morphology skills. It is a practical addition to the libraries of both trainees and practicing pathologists