The Pathology of Tumors Part II: Diagnostic Techniques

Frozen section diagnosis of cancer is generally used to 1) determine the type and extent of treatment while the patient is in the operating room and 2) to confirm the adequacy of surgical excision. Frozen section diagnosis forms the basis for further surgery. Because of the pathologist's role in this decision, he should be as familiar as possible with pertinent clinical data (e.g., previous biopsy or surgery) prior to operation. In some cases he may wish to observe the lesion in situ or suggest an area to be biopsied. Frozen section is very reliable in cancer diagnosis. A recent review of 2,240 consecutive sections has shown an overall accuracy of 99.3 percent with 13 false-negatives and only five false-positives. The technique is useful for most specimens, even tissue from needle biopsies. When the pathologist receives the gross specimen he must orient it and describe the color, consistency and size of the tumor and record its appearance prior to sectioning. The specimen must be carefully examined for any indications of inadequate tumor excision. Specimens may have critical areas close to the wound limits and the sections must be careflly oriented to prove or disprove adequate excision. Specimen roentgenography is very useful in evaluating excision and in pinpointing the tumor area. Microscopic description of tumors includes details of pattern, nuclear changes, stroma, and many others. However, only the microscopic findings which have prognostic or therapeutic significance should be emphasized to the surgeon. Summarizing the pertinent findings in a final paragraph of the pathology report can translate routine microscopic description into constructive clinical information which will give the surgeon a clear idea of the probable behavior of the tumor. In addition to the standard procedures for preparing and examining specimens for final diagnosis, there are some special techniques which are extremely useful. These include immunohistochemical staining, electron microscopy, tissue culture and biochemical studies.