Two rare cases of paraganglioma in patients with Fontan physiology.

Pheochromocytoma/paraganglioma is an exceedingly rare tumour, thought to share an association with cyanotic CHD. This association is thought to be a result of chronic hypoxaemia (Antonio et al, Revista Española de Cardiología (English Edition) 2017; 70: 673-675; Folger et al, Circulation 1964; 29: 750-757; Opotowsky et al, J Clin Endocrinol Metab 2015; 100: 1325-1334) We report two cases of paraganglioma over a 4-year period in patients with hypoplastic left heart syndrome who had undergone Fontan completion by ages 2 and 4. Based on a very small number of reported cases of CHD, the mechanism of tumourigenesis is unclear. It is imperative that cases associated with CHD continue to be reported so that we may learn more about the pathogenesis and epidemiology of this entity.