Due to its many clinical and biologic characteristics, neuroblastoma (NB) is a polyhedric neoplasm. It is a very complex, extremely heterogeneous disease that can regress spontaneously even without therapy. However, it frequently shows a very aggressive behavior, refractory to current intensive multimodal therapy. The tumor, originating from primordial neural crest cells, is biochemically unique for its metabolic pathways of catecholamine synthesis and metabolism. Homovanillic acid (HVA), the main metabolite of dopamine, and vanillylmandelic acid (VMA), the main metabolite of adrenalin and noradrenalin, are sensitive and convenient markers of NB since they are found in large amounts in patient's urine. The rate of NB patients with positive VMA and/or HVA at the diagnosis varies with the stage of the disease, with high-stage tumors being more likely to …