The Pathologic Evaluation of Neoplastic Diseases

The pathologist's understanding of oncologic disorders has progressed far beyond the recognition of abnormal tissues by gross or microscopic examination. Today, the laboratory specialist plays an integral role in eliminating incorrect differential diagnostic considerations, determining prognostic factors, evaluating treatment outcomes, and otherwise supporting the multidisciplinary care of oncology patients. The light microscope continues to serve as the cornerstone of surgical pathology, and the simple use of paraffinembedded tissue sections or cytology specimens is sufficient to make the final diagnosis for the great majority of malignant neoplasms. However, in about 10% of all oncology cases, the routinely assessed microscopic features are insufficient for a definitive diagnosis, and in these cases ancillary testing must be performed by a variety of techniques, including classical cytogenetics, flow cytometry, immunohistochemistry, and molecular genetic analysis. The use of ancillary techniques not only often permits more definitive diagnosis, but also provides predictive and prognostic information that is used to direct therapy.