Neural Crest Cell Tumors

Neuroblastoma, ganglioneuroblastoma, andganglioneuroma are tumors of varying maturity derived from the primordial neural crest cells that form the sympathetic nervous system. These precursor cells may remain undifferentiated (referred to as neuroblasts) or they may mature (to ganglion and Schwann cells). A tumor composed primarily of neuroblasts is referred to as neuroblastoma (NB), a tumor composed entirely of mature ganglion cells and other mature tissue is a ganglioneuroma(GN), and a tumor with both immature and mature cell types is a ganglioneuroblastoma (GNB). As a group, these tumors define a spectrum of sympathetic neuroectodermal tumors, ranging from the undifferentiated NB to the mature GN. The presence of immature tissue in NB and GNB indicates malignant or potentially malignant behavior; GN is considered benign.

They arise wherever sympathetic tissue exists and may be seen in the neck, posterior mediastinum, adrenal gland, retroperitoneum, and pelvis. The three tumors differ in their degree of cellular and extracellular maturation; immature tumors tend to be aggressive and occur in younger patients (median age, just under 2 years), whereas mature tumors occur in older children (median age, approximately 7 years) and tend to behave in a benign fashion. The most benign tumor is the ganglioneuroma, which is composed of gangliocytes and mature stroma. Ganglioneuroblastoma is composed of both mature gangliocytes and immature neuroblasts and has intermediate malignant potential. Neuroblastoma is the most immature, undifferentiated, and malignant tumor of the three. Neuroblastoma, however, may have a relatively benign course, even when metastatic. Thus, these neuroblastic tumors vary widely in their biologic behavior. Features such as DNA content, tumor proto-oncogenes, and catecholamine synthesis influence prognosis, and their presence or absence aids in categorizing patients as high, intermediate, or low risk. Treatment consists of surgery and, usually, chemotherapy. Despite recent advances in treatment, including bone marrow transplantation, neuroblastoma remains a relatively lethal tumor, accounting for 10% of pediatric cancers but 15% of cancer deaths in children.