DNA MEASUREMENTS IN THIN-SECTIONS OF LYMPHOMAS

: The DNA content of the nuclei of lymphomas and a reactive lymph node was studied by light absorption measurements in Feulgen-stained thin (2 microns) sections of lymph node biopsies, using the TAS image analysis system. For each nucleus, the integrated light absorbance at 548 nm wavelength was multiplied by the square root of the nuclear area to obtain a parameter for DNA independent from the nuclear size. In a hyperplastic reactive lymph node with follicular hyperplasia, the distribution of DNA X square root area was different in centrocytes and centroblasts, being compatible with a diploid centrocyte fraction and a mainly tetraploid centroblast fraction, in which hypertetraploid (octoploid?) nuclei were present. Similar measurements in three follicular centroblastic-centrocytic lymphomas gave similar results, with the centroblasts mainly tetraploid. The DNA distribution was studied in sections of lymphomas of high and low grades of malignancy, classified visually on the number of mitoses seen per field. The distribution width, from the smoothed histogram as the DNA X square root area values beyond the maximum peak frequency, appeared to be larger in the high-grade malignant lymphomas, in accordance with their higher number of mitoses.