What are the histologic characteristics of pediatric neuroblastoma?

Updated: Oct 09, 2017
  • Author: Norman J Lacayo, MD; Chief Editor: Max J Coppes, MD, PhD, MBA  more...
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Answer

Pluripotent sympathetic stem cells migrate and differentiate to form the different organs of the sympathetic nervous system. The normal adrenal gland consists of chromaffin cells, which produce and secrete catecholamines and neuropeptides. Other cells include sustentacular cells, which are similar to Schwann cells, and scattered ganglion cells. Histologically, neural crest tumors can be classified as neuroblastoma, ganglioneuroblastoma, and ganglioneuroma, depending on the degree of maturation and differentiation of the tumor.

The undifferentiated neuroblastomas histologically present as small, round, blue cell tumors with dense nests of cells in a fibrovascular matrix and Homer-Wright pseudorosettes. These pseudorosettes, which are observed in 15-50% of tumor samples, can be described as neuroblasts surrounding eosinophilic neuritic processes. The typical tumor shows small uniform cells with scant cytoplasm and hyperchromatic nuclei. A neuritic process, also called neuropil, is a pathognomonic feature of neuroblastoma cells. NSE, chromogranin, synaptophysin, and S-100 immunohistochemical stains are usually positive. Electron microscopy can be useful because ultrastructural features (eg, neurofilaments, neurotubules, synaptic vessels, dense core granules) are diagnostic for neuroblastoma.

In contrast, the completely benign ganglioneuroma is typically composed of mature ganglion cells, Schwann cells, and neuritic processes, whereas ganglioneuroblastomas include the whole spectrum of differentiation between pure ganglioneuromas and neuroblastomas. Because of the presence of different histologic components, the pathologist must thoroughly evaluate the tumor; the regions with different gross appearance may demonstrate a different histology.

Neuroblastic nodules are present in the fetal adrenal gland and peak at 17-18 weeks' gestation. Most of these nodules spontaneously regress and likely represent remnants of fetal development. Some of these may persist and lead to the development of neuroblastoma.


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