Early-onset pheochromocytoma with a somatic EPAS1 mutation in an 8-year-old boy with unrepaired pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries.

We report the case of an 8-year-old boy with unrepaired cyanotic CHD who developed pheochromocytoma and presented with hypertensive heart failure. Imaging revealed a tumour in the right adrenal gland. A genetic analysis identified a somatic EPAS1 mutation. This case highlights the potential for early pheochromocytoma development in patients with unrepaired CHD and severe cyanosis. This case provides a hypothesis-generating observation suggesting that chronic hypoxia may act synergistically with a pseudohypoxia mutation, potentially leading to an earlier-than-expected presentation of pheochromocytoma.