Ultrastructural study of two central nervous system lymphomas.

Electron microscopy was performed on two CNS lymphomas, one primary and the second a skull metastasis from a brain primary lymphoma. The former revealed a tumor perivascularly arranged, which was composed of rounded cells having no specialized organellae. Biopsies from the primary and metastasis of the second case revealed a predominance of rounded cells with scanty cytoplasm, another population of cells with phagocytic activity and a third group with elongated ctyoplasmic processes which stain positively for microglia. By electron microscopy some of these processes resembled neurites or oligondendroglia, while others suggested an astrocytic appearance.