VIP and neuroblastoma: We used the following keywords in the MEDLINE, EMBASE, and LILACS databases: "Neuroblastoma", "Ganglioneuroblastoma", "Ganglioneuroma", "Neural Crest tumor", "paravertebral mass", "mediastinal mass", "neurogenic tumor" and "tumor", joined by combined Boolean terms and the keywords "diarrhea", "paraneoplastic syndrome", "weight loss", "primary syndrome", "secondary syndrome", "Vasoactive Intestinal Peptide", "neuronal peptide", "vipoma", "verner-morrison syndrome", "VIP-secreting tumor", "WDHA", "WDHH", "WDHA syndrome", "WDHH syndrome".