Membranous changes in primary malignant CNS lymphomas.

Ultrastructural studies of 17 primary malignant CNS lymphomas revealed 6 tumors with abnormal intracytoplasmic and/or intranuclear membranous structures, most frequently associated with the endoplasmic reticulum or perinuclear envelope. In most cases, tubuloreticular inclusions and paired cisternae were present. Less frequent were accumulation of microtubules, concentric lamellar bodies, and rod-like or paracrystalline intranuclear inclusions. The specificity and significance of these membranous structures remain questionable because of their frequent occurrence in a variety of normal and pathological conditions. Some of these changes may be considered as cellular reactions to viral infections, others may indicate cellular activity or degeneration.