Diffuse large cell lymphomas (reticulum cell sarcomas, histiocytic lymphomas). Correlation of morphologic features with functional markers.

Electron microscopic findings in 15 cases of diffuse large cell lymphoma were correlated with other morphologic features, surface immunotype and cytoplasmic immunoglobulin content. Immunologically, the cases were: B cell, 8; null, 4; T cell, 2; and H cell (true histiocytic), 1. Ultrastructurally, all B cell and three null lymphomas were characterized by an abundance of polyribosomes and segments of rough endoplasmic reticulum. Concentric rough endoplasmic reticulum was observed in 4 cases of B cell lymphoma containing cytoplasmic immunoglobulin and in a null lymphoma. In 1 case of B cell lymphoma, the diastase-sensitive, periodic-acid-Schiff-positive cytoplasm showed evidence of widely dispersed monoparticulate glycogen granules. The two T cell lymphomas contained hyperlobulated or single round nuclei, and abundant smooth to rough endoplasmic reticulum. One null lymphoma appeared to share the ultrastructural features of T cell convoluted nuclei and the cytoplasmic organelles of myeloid precursor cells. The H cell lymphoma had features of monocytic-macrophagic differentiation. The large cell lymphomas, a morphologically and functionally heterogeneous group, were represented predominantly in this series by neoplasms with follicular center cells or early plasma cells.