An Unusual Cytoplasmic Ribosomal Structure in Pathologic Lymphocytes

Blood slides of a 70-yr-old woman with lymphosarcoma cell leukemia showed 10%-40% notched-split nucleated lymphocytes. A few round, nucleated lymphocytes contained a round or oval body close to the nucleus. The electron microscopic counterpart of this body was a complex tubular structure described previously by D. Zucker-Franklin. The walls of this structure are composed of granules on concentric layers of membranes around a central "core." The ribosomal nature of this structure is evidenced by: (1) similarity of the particles ot ribosomes, (2) the structure’s connections with endoplasmic reticulum, and (3) the ribonuclease effect on the corresponding paranuclear bodies in the blood slides. As an incidental finding, a very few round nucleated lymphocytes showed nuclear blebs only.