Large cell lymphoma with microvillus-like projections: an ultrastructural study.

On many of the cells of each of the 10 large cell lymphomas we studied, electron microscopy demonstrating slender peripheral cytoplasmic projections that simulated microvilli. They varied in number, but, when numerous, easily could be misinterpreted as evidence of adenocarcinoma. Immunoperoxidase staining confirmed the presence of monoclonal cytoplasmic immunoglobulin in four of 10 cases. Stains for muramidase were negative in every case. Because nine of the 10 cases were of presumed B-cell lineage, the lymphoma cells are compared to transformed lymphocytes from the follicular centers of reactive lymph nodes.