INTRODUCTION: The purpose of this study was to address the gap in knowledge in the incidence, presentation and imaging features of PPGL in Fontan patients. It has been hypothesised in the literature that Fontan circulation patients have an increased incidence of these tumours. This study is the largest cohort of adult Fontan patients in North America. The Fontan procedure is a palliative procedure for single ventricle congenital heart disease where the systemic venous return is directed into the pulmonary circulation. Fontan patients are at increased risk of developing several extracardiac complications including phaeochromocytoma and paraganglioma (PPGL). METHODS: This retrospective single-centre study includes all adult patients who were treated between 1 September 2015 and 1 September 2022 in a tertiary referral centre for adult congenital heart disease. Imaging and electronic medical records were retrospectively searched for the presence of PPGL. RESULTS: Five hundred and forty-seven Fontan patients were included in the study. Three patients had PPGL with an incidence of 0.5%. Two patients were diagnosed with paraganglioma and one with phaeochromocytoma. All patients were female. Median age of Fontan procedure was 1.8 years (range: 1.75-27 years). Median age of PPGL diagnosis was 19 years (range: 12-39 years). Median time from Fontan operation to diagnosis of PPGL was 12 years (range: 10.3-17.2 years). CONCLUSION: Fontan patients are at increased risk of PPGL. Clinically, the diagnosis of PPGL is challenging as symptoms and serum markers can be confounding in this population
however, the imaging features of PPGL remain typical making the role of the radiologist crucial.