Congenital neuroblastoma, neuroblastoma in situ, and the normal fetal development of the adrenal.

In normal fetal development nodular collections of neuroblast cells were found in the adrenal glands from 7 wk gestation; there nodules increased in size and number, and in all specimens from fetuses of 14-18 wk gestation, aggregates of nodules closely resembling neuroblastoma in situ could be found. From about 12 wk gestation the large neuroblast nodules appear to split into smaller nodules and differentiation into chromaffin cells takes place. The mean nuclear size of neuroblasts at all stages of development studied was 4.25 +/- 0.84 mu, statistically significantly less than the mean nuclear size of the cells measured in 7 neonatal neuroblastomas. Measurement of nuclear size may be a way of distinguishing a true potentially malignant neuroblastoma in situ from a normal benign residual neuroblast nodule.