Favorable histology, MYCN-amplified 4S neonatal neuroblastoma.

We report a neonate with 4S neuroblastoma and MYCN amplification, but favorable Shimada histology, successfully treated with chemotherapy and 13-cis-retinoic acid without stem cell transplantation. MYCN amplification in neuroblastoma is usually associated with unfavorable Shimada histology; the presence of these features in infants with 4S disease confers a poor prognosis. A small number of infants with 4S neuroblastoma and MYCN amplification have favorable Shimada histology. In this subgroup of infants, histopathology may be equally important in predicting outcome.