Prevalence of Neuroendocrine Tumors in Patients With Cyanotic Congenital Heart Disease

Congenital Cyanotic Heart Disease and the Association with Pheochromocytomas and Paragangliomas

PURPOSE OF REVIEW

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors that commonly produce excess catecholamines causing significant morbidity and mortality. Patients with cyanotic congenital heart disease (CCHD) develop PPGLs at a higher frequency than the general population. This review will summarize recent research in the association of PPGL and CCHD.

RECENT FINDINGS

Advances in molecular genetics have provided new insights into a variety of germline mutations and somatic mutations related to PPGLs. In the CCHD population, mutations can occur in the hypoxia signaling pathway with gain-of-function somatic mutations in EPAS1, which prevent degradation of hypoxia-inducible factor-2 alpha. These mutations are implicated in oncogenesis. PPGLs associated with CCHD develop as early as age 15 years and have predominantly noradrenergic secretion. Surgical removal is considered the first line of therapy, although belzutifan, a HIF-2α inhibitor, is currently being tested as a potential therapy. Early screening with plasma metanephrines may assist in identifying PPGLs in patients with CCHD.

Special situations in pheochromocytomas and paragangliomas: pregnancy, metastatic disease, and cyanotic congenital heart diseases

The aim of our study was to describe the epidemiology, diagnosis, and treatment of the most complex pheochromocytoma and paraganglioma (PGL) cases, including pheochromocytoma/PGL during pregnancy, in cyanotic congenital heart diseases (CCHDs), and metastatic pheochromocytoma. The English and Spanish literature was thoroughly evaluated searching for articles reporting clinical studies, case reports, or reviews of pheochromocytoma/PGL in pregnancy and in CCHD and metastatic pheochromocytoma/PGL. Particular settings in the diagnosis and management of pheochromocytoma and PGLs remain challenging. Those special situations include the diagnosis during pregnancy or in the context of CCHD since the typical clinical features of pheochromocytoma may be confounded with preeclampsia during pregnancy and with the complications commonly observed in CCHD. In addition, although some clinical and genetic features have been associated with higher risk of metastatic pheochromocytoma, the detection and prediction of the development of metastatic disease involve another complex situation that may require special hormonal determinations as plasmatic 3-methoxytyramine and nuclear medicine studies including ¹⁸FDG PET-CT or ¹⁸F-FDOPA PET-CT, among others. Furthermore, the selection of the most appropriate treatment in these situations, as well as the moment to carry it out, requires special care as limited evidence is available. This article reviews the epidemiology, diagnosis, and treatment of the pheochromocytoma/PGL during pregnancy, metastatic pheochromocytoma/PGL, and pheochromocytoma/PGL in CCHD. The diagnosis, and especially the treatment, of metastatic pheochromocytomas and pheochromocytoma/PGL during pregnancy and in CCHD is challenging. Thus, these cases should be management in reference centres by multidisciplinary teams specialized in the pheochromocytoma/PGL treatment.

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.