Evaluation of poorly differentiated head and neck neoplasms. Immunocytochemistry techniques

Despite the use of strict morphologic criteria, some head and neck neoplasms remain classified as "poorly differentiated" or "undifferentiated." To circumvent this diagnostic quandary, newer techniques primarily based on immunocytochemistry are being utilized to study tumor specimens. These methods rely on the binding of specific antibodies to cellular antigens in order to better define the tumor according to cell type. We treated six patients in whom a definitive pathologic diagnosis could not be obtained without the use of immunohistologic stains. In each case, the definition of a specific tumor category altered patient management. The approach to the evaluation of patients with undifferentiated head and neck neoplasms is important. Close cooperation between the clinician and pathologist is necessary in such cases; this is assisted by a knowledge of the uses and limitations of the current diagnostic modalities being used, as well as proper tissue handling and processing.