This book presents clinicopathological insights into common genitourinary diseases, especially those of neoplastic nature, and introduces experiential learning based on case presentations (case-based learning). One of the tasks that trainees face is converting the extensive amount of data into medical experience. Using successive microscopic images, the book gradually and analytically presents diagnostic procedures for the genitourinary system (kidney, urinary bladder, prostate gland and testis). Characteristic cases are presented for each organ, each ending with a clinical commentary and key messages. This form of presentation helps readers acquire the valuable skill of effective diagnostic thinking, focusing their attention on the essential microscopic findings and disregarding insubstantial findings.