Plasmacytoid T-cell clusters in non-specific lymphadenitis.

The occurrence and morphology of Lymphoblastennester (clusters of lymphoblasts) were analyzed in 500 unselected cases of nonspecific lymphadenitis. Sixty-eight cases showed such clusters, which consist of uniform-looking medium-sized cells. Based on the results of recent immunologic investigations, these cells may be interpreted as T-cells with plasmacytoid features ("plasmacytoid T-cells', PTC). PTC were usually located near venules in the pulp, but not in the generally hyperplastic T-nodules. There was usually no relation to hyperplasia of B-regions (follicles). Although occasional mitotic figures and basophilic blast cells were found at the edges of PTC clusters, it is possible that PTC develop through transformation of T-lymphocytes. PTC often showed pyknotic nuclei and a tendency to perish, suggesting that they are end cells. Necrotic cells were phagocytosed by macrophages, which occasionally caused a starry sky pattern like that seen in germinal centers. Sometimes there were also a few interdigitating reticulum cells in the clusters. The function of PTC is still obscure; they might secrete lymphokines.