This classification represents a project aimed at bringing together the variety of ways thymic epithelial neoplasms have been classified. It focuses on their growth characteristics, and cytoarchitectural features . The classification, though restricted to the thymic region rather than the mediastinum in general, also covers neuroendocrine, germ cell, lymphoid, and stromal tumours, as well as tumour-like lesions and the neck tumours of thymic or related branchial pouch derivation.

In the years since the publication of the third edition, awareness of the remarkable morphologic diversity of thyroid carcinoma has notably expanded, and great advances have been made in unravelling the molecular genetic features of thyroid and parathyroid tumours. There has also been an increased interest in the use of the fine-needle aspiration technique for the diagnosis and management of thyroid tumours, and in the role of the pathologist in the operative handling of the hyperfunctioning parathyroid gland. This volume documents the most significant advances that have taken place since the previous edition, emphasising those with a practical application at the clinical level. The format remains similar to that of the previous versions, but the two thyroid and parathyroid editions have been merged into one, and most of the black and white images and photomicrographs have been replaced with colour. The authors include a number of the most recent references, but have not ignored the classic works in the field, many of which have descriptions, illustrations, and insights that cannot be bettered. This edition fulfils the original goal of this series, which is that of helping the pathologist diagnose and anticipate the behavior of the tumours and tumour-like lesions included in this publication.