Neuroblastomas are known to undergo spontaneous maturation or complete regression in some cases resulting in cure. Population-based screening studies of infants have shown that spontaneous regression is at least as common as neuroblastomas detected clinically in the first year of life. Spontaneous regression is more likely to be seen in the absence of adverse prognostic factors and usually occurs only in tumors with a) near triploid number of chromosomes, b) no MYCN amplification and c) no loss of chromosome 1p. This image is of a differentiating subtype of neuroblastoma. The differentiating neuroblasts are surrounded by abundant neuropil.