As in the second edition, the third edition of Handbook of Practical Immunohistochemistry – Frequently Asked Questions is written in a question and answer (Q&A) format and intended to be a practical, user-friendly, quick reference for information related to using the most up-to-date immunohistochemistry and in situ hybridization in clinical diagnosis. The new edition demonstrates a significant revision and improvement over the second edition. Five new chapters have been added that cover the following: 1) Immunohistochemistry: Leica’s perspective; 2) Immunohistochemistry: Maixin perspective; 3) RNA in situ hybridization: Applications in anatomic pathology; 4) Applications of rapid immunohistochemistry on frozen tissue sections during intraoperative pathologic diagnosis; and 5) Cutaneous lymphomas. In addition to extensive additions and changes, over 150 new questions and answers were added throughout this new edition. All chapters have been updated to include relevant new questions, new markers, more refined IHC panels, representative pictures, and current references. An extensive set of high-quality color pictures and diagnostic algorithms, if available, is included in each chapter to illustrate some of the key antibodies, including many recently discovered and substantiated antibodies used in that chapter.