Comparison of ultrastructural features among neuroblastic tumors: maturation from neuroblastoma to ganglioneuroma.

Neuroblastic tumors have the unique ability to differentiate and mature. This family of tumors is composed of the neuroblastoma, ganglioneuroblastoma, and ganglioneuroma. These tumors are derived from primordial neural crest cells that form the sympathetic nervous system. The purpose of this study was to characterize the ultrastructural features of neuroblastic tumors in a pediatric population. Forty-five neuroblastic tumors (15 neuroblastomas, 15 ganglioneuroblastomas, and 15 ganglioneuromas) were examined using standard transmission electron microscopic techniques. Undifferentiated neuroblastomas were composed of primitive cells with rare neurite-like processes containing clear secretory vesicles and no Schwann cell differentiation. Poorly differentiated and differentiating neuroblastomas showed more frequent neuritic processes with infrequent dense core granules and infrequent immature Schwann-like cells. Ganglioneuroblastomas possessed an admixture of cell types, including immature ganglion cells without associated satellite cells, intermediate cells, and differentiating neuroblasts. The neuropil contained immature Schwann cells encasing haphazardly arranged neuritic processes. Ganglioneuromas were composed of mature ganglion cells with occasional binucleation. The neuropil contained mature Schwann cells with well-organized neuritic processes and abundant collagen deposition. Differentiation or maturation of tumor cells, neuritic processes, and Schwann cells may thus be discerned ultrastructurally in primary neuroblastic tumors in pediatric patients.