Mantle zone lymphoma: a morphometric comparison with centrocytic and immunocytic lymphomas and reactive secondary...

Nuclear size and shape of lymphoid cells were evaluated morphometrically in the mantle zone lymphoma, immunocytic lymphoma, and centrocytic lymphoma, and were compared with those of reactive secondary follicles. Shape factors (forms Ar, Ell, Pe, and Dia) have been used to quantitatively define the most frequent nuclear profiles. One of the testing sets consisted of the nuclei of the light, dark, and mantle regions of reactive nodes, as well as those of the centrocytic lymphoma, immunocytic lymphoma, and the mantle-fashion growth lymphoma. Another testing set was made up of only the three types of lymphoma and was used for evaluating the variability of shapes within these groups by means of a pattern recognition algorithm. The content of reactive T lymphocytes was assessed in all cases by immunohistochemistry. The results of transforming centroid values into geometric shapes by computer modelling indicated that only minor geometric differences existed between the a priori qualitatively chosen nuclear types and those modeled a posteriori by computer. All the nuclear types were found in each of the reactive regions and in each of the lymphomas. However, highly significant differences of distribution were detected among the three categories of lymphoma and between each reactive region and each lymphoma. The cases of centrocytic lymphoma showed constant findings in terms of nuclear composition, while lymphomas with mantle-fashion growth and the examples of immunocytic lymphoma showed significant variability. These observations confirm that the centrocytic lymphoma represents a distinct entity, although its normal counterpart is still unknown, and question the view that the immunocytoma and the mantle zone lymphoma correspond to homogenous categories of non-Hodgkin's lymphomas. In addition, since all the qualitatively and quantitatively detected nuclear types were found in all the reactive regions and in all the lymphomas, albeit with different distributions, it has to be assumed that only numerical differences exist among the various lymphomas and the reactive regions.