Bruce R. Smoller, md, concisely reviews for practitioners and students alike the science of immunopathology, its many basic laboratory tools, and their multiple diagnostic uses in actual clinical case studies. The author presents in an easily digestible form a dictionary of antibody probes, summarizing for each antibody the targeted antigen and its cellular function, its diagnostic utility, and, when available, its sensitivities and specificities for identifying various neoplasms. Real clinical cases from the author’s practice demonstrate the benefits of immunopathology.