Large cell lymphoma. II. Differential diagnosis of centroblastic and B-immunoblastic subtypes by morphometry on cytologic preparations.

Measurements were made, using semiautomatic electronic planimetry, of nuclear and nucleolar parameters of cytologic preparations from 18 cases of centroblastic and 9 cases of B-immunoblastic Non-Hodgkin's lymphomas, in order to determine whether these two subgroups of large cell lymphoma could be differentiated objectively by morphologic criteria. Statistically significant differences between centroblastic and B-immunoblastic lymphoma occurred in the mean and standard deviation of nucleolar area, the mean nuclear area, and the number of nucleoli per nucleus. The most useful discriminatory parameter was mean nucleolar area. The mean percentage of immunoblasts, defined as cells with nuclear area greater than 35 micron 2 and mean nucleolar area greater than 3 micron 2, was significantly different between the two groups of patients. The results suggest that although the groups of centroblastic and of immunoblastic lymphomas can be differentiated by measurable morphologic criteria, the individual cases form a spectrum from nodular centroblastic through diffuse centroblastic to immunoblastic, with polymorphic forms in between. A comparison with the results of a similar study on histologic sections from the same patients demonstrated that morphologic measurements on these two types of material are not interchangeable but, in general, the same conclusions were reached by morphometric study on histologic and cytologic specimens.