Deparaffinization and Processing of Pathologic Material

DNA content has become an important diagnostic, as well as prognostic, method for clinical pathology and investigative oncology. Paraffin-embedded tissue can be examined by flow cytometric (FCM) methods for total DNA content and aneuploidy with respect to the classification of the original pathologic diagnosis. The relative significance of studies on archival material permits retrospective analysis on a great number of cases, studying different specimens of a tumor for intratumor heterogeneity while comparing results from previous pathologic evaluations (1 ). DNA content as measured in paraffin-embedded tissue is closely related to that obtained from fresh specimens. Still, a major drawback in the procedure is that only nuclei are recovered for analysis of DNA content.