Origin is neural crest. A ganglioneuroma is a benign tumor of neural crest origin that is completely differentiated. A tumor of neural crest origin that is intermediate in differentiation between neuroblastoma and ganglioneuroma are called ganglioneuroblastoma. A neuroblastoma is composed of dense sheets of small, round to fusiform cells with hyperchromatic nuclei and scanty cytoplasm and frequent mitoses. Homer-Wright rosettes, rim of dark tumor cells in a circumferential arrangement around a central pale fibrillar core.
Pseudo rosettes with tumor cells arranged around small vessels are also present.
A ganglioneuroma is well encapsulated and histologically has mature ganglion cells associated with scanty spindle cells in a loose and abundant stroma. A ganglioneuroblastoma has combination of these patterns having ganglions and immature cells. The neuroblastoma and ganglioneuroma show differentiation towards neuroblasts or neurons of the sympathetic ganglia. They do not show the same zellballen pattern seen with pheochromocytomas or paragangliomas even though these tumors are also of neural crest origin. Note the increase of parthyroid chief cells and loss of adipose tissue.