Ultrastructural characteristics of the "hairy cells" of leukemic reticuloendotheliosis.

The pathognomonic neoplastic reticulum cells, or "hairy cells" of leukemic reticuloendotheliosis from 6 patients were studied with the electron microscope. These cells demonstrated characteristic ultrastructural features which were distinctly different from those of lymphocytes, monocytes, or histiocytes. In 3 patients a distinctive ribosome-lamella complex was found. The biologic significance of this unusual cytoplasmic inclusion is still unknown. Its frequent presence in leukemic reticuloendotheliosis and its rarity in other neoplastic diseases suggest a substantial yet unexplained relationship between this complex and leukemic reticuloendotheliosis.