Since the publication of the Third Series Fascicle of the Uterine Corpus nearly thirty years ago, molecular discoveries have deepened our understanding of epithelial, mesenchymal, and mixed müllerian tumors of the uterus, fueling a new and still evolving classification of the different categories of uterine neoplasms. Enormous insights have been made to refine the classification of the different subtypes of endometrial carcinoma linked to important prognostic and therapeutic implications. At the same time, molecular findings have allowed for the discovery of familial syndromes associated with uterine corpus neoplasms, and identification of patients at increased risk for developing specific tumors, with the subsequent implementation of genetic counseling and appropriate treatment guidelines. Molecular underpinnings have also assisted in the development of new and potentially more predictive morphologic criteria for endometrial preneoplasia, namely the endometrial intraepithelial neoplasia (or EIN) system. In this Uterine Corpus Fascicle, there is an increased emphasis on the cytopathologic (intraoperative, exfoliative, or fine needle aspiration) and molecular features that are important in diagnosis and prognosis. What does not change from the three previous series, however, is the goal of providing the reader with thorough, concise, and up-to-date information on the nomenclature and classification; epidemiologic, clinical, and pathogenetic features; and, most importantly, guidance in the diagnosis of the tumors and tumorlike lesions of all major organ systems and body sites. Order the Tumors of the Uterine Corpus and Trophoblastic Diseases now to take advantage of these new discoveries and techniques for diagnosing and treating these types of tumors.