Immunohistochemistry (IHC) is widely and integrally employed in surgical pathology, and has become critical in many diagnostic settings. The first part of this short course updates pathologists on many of the problems relating to preanalytical, analytical, and postanalytical (interpretive) factors that can potentially lead to incorrect interpretations and diagnoses. These factors include incorporating the correct antibodies into the diagnostic panel, optimal fixation and epitope retrieval techniques, misinterpretation of immunostained slides and misinterpretation of the significance of selected immunostaining results. The second part of the course is a series of case studies highlighting the impact of IHC on tumor diagnosis, using the examples of: (a) carcinoma of unknown primary arising in the liver; (b) small, blue round cell tumor in the nasopharynx; (c) spindle cell tumor in the lung. Discussion will be focused on selection of optimal antibody panels to maximize sensitivity and specificity. The third part of the course is a review of the utility and application of several novel IHC markers, including napsin A (lung cancer), INI1 (epithelioid sarcoma and rhabdoid tumors), PAX8 (ovarian tumors), arginase 1 (hepatocellular carcinoma), beta catenin (subset of mesenchymal tumors) and TLE1 (synovial sarcoma). This course will benefit pathologists at all levels of training. Registrants will receive a syllabus at the course and have access to after meeting materials on the USCAP website.

(NEW COURSE) This course may be used for CME credits or SAM credits.