Gastrointestinal neuroendocrine tumors in Fontan patients.

The Fontan procedure used for palliation of single ventricle physiology is associated with multisystemic morbidity. With improving survival and increased use of surveillance imaging in this patient population, long-term complications associated with Fontan circuits are commonly encountered by radiologists. One interesting observation is the apparent increased risk of paragangliomas and pheochromocytomas in this group of patients and perhaps a pathogenetic role of chronic hypoxia. We report 2 cases of gastrointestinal neuroendocrine tumors (NET) in the setting of Fontan circuit. The first is a 20-year-old female with history of hypoplastic left heart and Fontan palliation who presented with hematochezia and was diagnosed with a jejunal grade 2 NET. The second case is of a 12-year-old boy with history Fontan palliation for single ventricle physiology, incidentally found to have a well-differentiated pancreatic NET during precardiac transplant workup. These cases should alert the radiologists to be aware of the apparent association between Fontan procedure and NET.