Ultrastructural Observations on Neuroblastic Tumors in Childhood: A Study of Tumor Cell Differentiation and Regression on 89 Cases

Overview

The study presents ultrastructural findings in 89 neuroblastic tumors. All of them including 21 undifferentiated neuroblastomas (NB) were characterized by neural cell processes which contai- ned neurofilaments, mitochondria and neurosecretory granules. The granules were generally sparse and their number and distribution was a feature independent on other signs of differentia- tion of the tumor cells. We found degenerative changes in the tumor cell bodies and their neuro- nal processes to be a prominent phenomenon in neuroblastic tumors. Although they occurred both in patients who were operated primarily and in those who received a preoperative chemo- therapy they were most conspicuous in the latter group (28 of 80 patients). The degenerative changes included swelling and dilatations of the neuronal processes, accumulation of heteropha- gosomes, myelinated bodies and cytoskeletal filaments. Some ganglion cells had dilated endoplas- mic reticulum, and contained lipofuscin. In one ganglioneuroblastoma we detected dense granulated bodies resembling neuromelanin. The diagnosis of undifferentiated NB was estab- lished on the basis of ultrastructural investigations in 13 out of 21 undifferentiated NB; in the remaining 8 cases the electron microscopy was an additional confirmatory tool together with the results of immunohistochemical reactions. The electron microscope is still a valuable instrument for diagnosis of neuroblastic tumors in addition to newer diagnostic approaches such as immuno- histochemical and molecular investigations.

Key words:
neuroblastoma - ganglioneuroblastoma - ganglioneuroma - ultrastructure - degenerati- ve changes