Exponential progress in the identification of new diagnostic molecular markers has been made in recent years. Appropriately applying these new markers in surgical pathology can be challenging. This course will provide a review and update of practical diagnostic immunohistochemistry in genitourinary pathology with a focus on solving commonly faced problems. It is designed for general practicing pathologists, pathologists-in-training, and pathologists with a special interest in genitourinary diseases.

A case-based and scenario-orientated slide seminar will outline an integrated systematic clinicopathological and immunohistochemical approach to accurately diagnosing frequently encountered difficult cases in daily practice. Ten cases, including prostate, bladder, kidney, and testis, will be analyzed for key histological features, commonly encountered mimicking lesions, major differential diagnoses, possible pitfalls, and subsequent clinical significance. Specific dilemmas will be identified and discussed including a small focus of prostatic adenocarcinoma and its mimicking lesions; the classification of the histological variants of infiltrating urothelial carcinoma; the separation of nephrogenic adenoma from urothelial and prostatic adenocarcinoma; and the differentiation of muscularis mucosa from muscularis propria involved by urothelial carcinoma. Additionally, special attention will be placed upon the differential diagnoses among renal tumors; the identification of metastatic clear cell renal cell carcinoma; and the classification and component estimation of a mixed testicular germ cell tumor.

Emerging biomarkers, such as AMACR, PIN4, ERG, CA9, PAX2, PAX8, smoothelin, OCT3/4, SALL4, glypican 3, and others, will be discussed to demonstrate their applications in differential diagnoses and clinical and therapeutic implications. An appropriate panel of antibodies, working algorithms, immunostain interpretations, and potential pitfalls will be emphasized.

Virtual slides, still images, and case histories will be posted on the USCAP website for review prior to the meeting. An interactive style will be used; input as well as questions from the audience will be encouraged and appreciated. All participants will receive online access to all the histological images used during the live lecture (original complete presentation) and a syllabus reviewing diagnostic features with a comprehensive reference list.

Upon completion of the course, you will be able to: 1) explain frequently encountered diagnostic dilemmas in the genitourinary system; 2) select an appropriate panel of immunohistochemical markers; 3) gain expertise in interpreting immunostains; and 4) avoid or minimize pitfalls. Cautious and well-informed utilization of diagnostic immunohistochemistry will be of significant value to your daily practice.

(LAST SCHEDULED PRESENTATION) This course may be used for CME credits or SAM credits.