The dendritic reticulum cell pattern in B cell lymphomas of the small cleaved, mixed, and large cell types: An immunohistochemical study of 48 cases

An immunohistochemical study was designed to study the dendritic reticulum cell (DRC) patterns in 48 cases of B cell non-Hodgkin's lymphomas of the small cleaved, mixed, and large cell types, both follicular (20 cases) and diffuse (28 cases), in order to evaluate the possible influence of DRCs on homing and the differentiation o of neoplastic B cells. Three DRC patterns were observed. In the follicular lymphomas, DRCs constituted nodular networks of variable density. In the diffuse lymphomas, DRCs were present either as isolated and scattered cells (17 cases) or constituted irregular meshworks of variable sizes (11 cases). These DRC patterns correlate with B cell immunophenotypes. Like follicular lymphomas, and unlike diffuse lymphomas without DRC networks, diffuse lymphomas with DRC networks constantly expressed the pan B antigens and one marker characteristic of normal germinal center cells, CD21 antigen, the C3d receptor. The finding of organized DRC networks in a significant number of diffuse lymphomas does not substantiate the hypothesis that DRCs may play a role in the homing of neoplastic B cells. The correlations observed between DRC patterns and B cell immunophenotypes suggest that the persistence and/or the development of DRC networks within follicular center cell-type lymphomas are related to the degree of functional differentiation of neoplastic B cells.