Morphometric analysis of bovine lymphomas classified according to the National Cancer Institute working formulation

The National Cancer Institute Working Formulation (NCI-WF) for the subjective classification of human non-Hodgkin's lymphoma is readily applicable to the classification of bovine lymphomas. Forty-nine cases of bovine lymphoma were analysed morphometrically to see if nuclear size and cleavage were distributed continuously or discretely between different NCI-WF tumour cell types. The mean nuclear area (+/- standard error of the mean, SE) was significantly greater (P < 10(-6)) in cells from the different types of diffuse large-cell lymphoma than in cells from the different types of small-cell lymphoma (42.91 +/- 1.21 micron 2 vs 19.33 +/- 1.08 micron 2, respectively); there was no overlap between the two groups. The mean nuclear are (+/- SE) of cells from diffuse large-cell lymphomas was significantly greater (P < 10(-4)) than that of cells from small non-cleaved lymphomas (42.74 +/- 1.72 micron 2 vs 27.54 +/- 1.08 micron 2, respectively), and there was again no overlap between the two groups; these two cell types are difficult to distinguish by any criteria other than size. Additionally, the cell-to-cell variability in nuclear area within a given tumour was significantly greater (P < 0.001) for the diffuse large-cell type than for the small non-cleaved cell type. The mean nuclear form factor (+/- SE) and mean nuclear contour indices (+/- SE) of the diffuse large cleaved cell type (0.53 +/- 0.02 and 5.08 +/- 0.11, respectively) were significantly different (P < 0.01 to 10(-6)) from the same parameters in the diffuse large-cell type (0.82 +/- 0.01 and 3.94 +/- 0.04, respectively). Some of the major criteria of the NCI-WF used subjectively to discriminate between bovine lymphoma cell types were supported by morphometric measurements. The magnitude of the differences in nuclear morphological characteristics between bovine lymphoma cell types was such that there was no overlap.