The tumors that arise in the adrenals and extra-adrenal paraganglia are not only structurally and hormonally complex, they are also intriguing at the molecular level, where many are recognized as components and harbingers of familial genetic tumor syndromes encompassing a variety of mutations affecting diverse signaling pathways. Building on the foundation laid by the fourth series volume, this fifth series ARP Fascicle summarizes and illustrates the large body of knowledge in this field to provide a comprehensive reference for the clinical, biochemical, radiologic, histologic, immunohistochemical, and molecular features of the various tumors and tumor-like conditions that affect the adrenals and extra-adrenal paraganglia.