The mediastinum is a hollow space within the thoracic cavity that may give rise to a wide spectrum of tumoral conditions from the benign to the intermediate to the highly malignant neoplasms. In addition, other inflammatory and infectious conditions may also arise in this space, which renders the practice of mediastinal pathology, almost a general surgical pathology practice. However, there are numerous mediastinal conditions that are important not only for diagnosis but also for treatment and clinical outcome. Due to the unusual location and because of the complexity of the tumors occurring in the mediastinum, there are only a few experts in this particular anatomic area. In fact, there are no more than 3-4 individuals worldwide with enough experience to properly diagnose, classify, and make treatment suggestions when these tumors arise in the mediastinum. More recent developments in tumor diagnosis and classification have created a vacuum in the general pathologist who often is confronted with this pathology and becomes uneasy about the specifics. For instance, recent developments in tumor pathology have led to the classification and staging of mediastinal tumors in more innovative ways that are in need of proper highlighting. Needless to say, even though there are a few publications on mediastinal pathology, the books are either obsolete or incomplete, in addition of providing superficial knowledge. Unfortunately and with all due respect to the authors of those publications, neither of those books is written by experts in the area. Rather the books were written out of the lack of information in mediastinal pathology. Even the World Health Organization (WHO) publication, which is truly more on lung and pleural neoplasms, has inserted in its contents a portion of mediastinal tumors, such portion not only is superficial and incomplete but also at least highly controversial if not flat out incorrect. . This text's goal is to present comprehensive and up to date information of the diverse pathology that can be encountered in the mediastinal compartment. The book will be divided in 11 different chapters based on the lineage of the diverse tumors that occur in the mediastinum, i.e. epithelial, neuroendocrine, lymphoid, etc (see table of contents). In addition, two separate chapters will be included -one on the radiological aspects and the others on the surgical approach to the different mediastinal tumors., bringing a total of 13 chapters. In the pathology section, the book will include current staging and classification systems of the different tumors. In addition, it will address the most current criteria for diagnosis and the differential diagnosis. Although the emphasis of the book is on diagnostic surgical pathology, every chapter will include the use of immunohistochemical techniques, electron microscopy, and molecular biology when necessary. The book will be extensively illustrated so that the reader will benefit of the different histomorphology of mediastinal tumors. Because of the nature of this specific anatomic area and the need to develop a standard text, Mediastinal Pathology should be of high interest to general surgical pathologists, thoracic pathologists in particular as well as thoracic surgeons, oncologists, and radiologists. Needless to say, this book will be of interest to pathology residents and fellows as well as to those seeking more in depth knowledge of thoracic - mediastinal pathology.