Cytogenesis and differentiation of pineal neoplasms.

Our knowledge of pineal neoplasms is still fragmentary, but a pattern is beginning to emerge in this highly challenging area of neuro-oncology. In vitro studies and more complete morphologic and biochemical characterization are still needed for these very rare neoplasms. Follow-up data from appropriate clinical series are still almost nonexistent for the evaluation of therapeutic effectiveness. As an illustration of neoplastic development, the demonstration of divergent differentiation in pineal parenchymal tumors represents a most intriguing phenomenon in light of the origin, structure, and function of the pineal gland.