DNA quantitation by image cytometry of touch preparations from fresh and frozen tissue

Using formalin-fixed, paraffin-embedded tissue for DNA quantitation has several disadvantages, including sacrifice of tissue and relatively poor resolution. DNA quantitation of touch preparations by image cytometry correlates well with flow cytometry, and analysis of touch preparations made from frozen tissue may offer an alternative method for retrospective studies. The authors compared the results of DNA quantitation of fresh and frozen tissue touch preparations in 59 solid tumors. For 54 cases there was excellent correlation. In three cases with multiple aneuploid peaks, the same populations were identified by each method, but different proportions of cells from each stemline were present in the fresh and frozen samples. In two cases there was a discrepancy between the DNA indices; the imprints showed different cell morphologic characteristics, suggesting different stemlines or areas of tumor differentiation. The authors conclude that DNA quantitation from touch preparations of frozen tissue by image cytometry provides a desirable alternative to sacrificing formalin-fixed tissue.