Flow cytometric analysis of DNA in diagnostic cytology

Flow cytometric analysis of nuclear DNA content and cell surface immunologic phenotyping were used in the evaluation of cytologic samples obtained from four patients. In each sample, a lymphoid cell population was present, which was difficult to evaluate by traditional cytopathologic methods. In two of the cases, the flow cytometric demonstration of monoclonal populations of lymphoid cells characterized by abnormal amounts of nuclear DNA gave support to the cytologic interpretation of malignancy. In a third sample, a lymphoid cell population that could not be cytologically distinguished from malignant lymphoma cells of small lymphoid cell type was shown to be composed of euploid, polyclonal cells. In the fourth case, the demonstration of euploidy in morphologically distinctive cell populations was helpful in interpreting the fine-needle aspirate of the thyroid gland. The authors conclude that flow cytometry can be used to great advantage in the evaluation of cytologic samples as well as in predicting biologic behavior.