Neuroblastoma is the most common solid tumor in children. It derives from the neural crest and originates from the sympathetic neuronal lineage [1-3]. At least two distinct biological-clinical entities can be distinguished [3-6]. One favorable subset occurs exclusively in infants and consists of early stages (I and II) as well as widespread disease (stage IV-S) at diagnosis. These tumors are commonly characterized by a hyperdiploid or pseudotriploid karyotype, but lack structural chromosome abnormalities. In particular, 1p abnormalities or N-myc gene amplification are not observed. Virtually all tumors identified with mass screening have belonged to these lower stages [4, 7, 8]. These patients show an excellent clinical outcome despite no or only minimal therapy. The other group of unfavorabled neuroblastomas is associated with older age and advanced stages (stages III and IV), and pseudodiploid karyotypes including lp deletions and N-myc oncogene amplification [2, 9]. Their outcome remains poor despite aggressive multimodality therapy and bone marrow transplantation. It is interesting to note that favorable neuroblastomas rarely, if ever, evolve into unfavorable disease [3].