Vasoactive Intestinal Peptide (VIP)-Secreting Neuroblastic Tumors in Children Presenting With Chronic Secretory Diarrhea: A Report of Two Cases.

Vasoactive intestinal peptide (VIP)-secreting neuroblastic tumors are rare pediatric neoplasms that may present with chronic secretory diarrhea prior to tumor detection, posing significant diagnostic and therapeutic challenges. VIP-induced diarrhea is typically profuse, watery, and refractory to standard management, often resulting in dehydration, electrolyte imbalance, weight loss, and failure to thrive. Herein, we report two pediatric patients with neuroblastoma who presented with chronic secretory diarrhea as the initial and predominant symptom. In both cases, the persistent diarrhea remained unexplained by common etiologies and was unresponsive to conventional therapies. After approximately three months of ongoing symptoms accompanied by progressive abdominal distension, radiologic evaluation revealed intra-abdominal masses in both cases. The diagnosis of neuroblastoma was confirmed by tumor biopsy in one patient and bone marrow biopsy in the other. Serum VIP levels were not available in either case; however, the clinical presentation was consistent with VIP-mediated secretory diarrhea. Although surgical resection of VIP-secreting neuroblastic tumors in localized disease is typically associated with resolution of diarrhea and favorable outcomes, delayed diagnosis could result in advanced, metastatic, and inoperable disease. Both of our cases had metastatic, inoperable disease at the time of diagnosis, and proved fatal in one. These cases underscore the importance of considering VIP-secreting neuroblastic tumors in the differential diagnosis of children presenting with unexplained, treatment-resistant secretory diarrhea. Early recognition may facilitate timely diagnosis and improve clinical outcomes.