Extremely enlarged right atrial appendage in paediatric idiopathic pulmonary hypertension.

We report an extremely rare case of a right atrial appendage aneurysm in idiopathic pulmonary arterial hypertension (PAH) identified at autopsy. The female patient was diagnosed with idiopathic PAH at the age of 7. Despite intensive treatment, she expired due to cardiac failure at the age of 18. At autopsy, initial thoracotomy revealed an extremely enlarged intrapericardial balloon-like chamber with characteristic horizontal stripes, which turned out to be a markedly dilated right atrial appendage. The histology of the lungs was compatible with idiopathic PAH. In cor pulmonale which may complicate PAH, the occurrence of a right atrial appendage aneurysm is extremely rare, although right ventricular dilatation is common. Improved prognosis and rare paediatric occurrence of idiopathic PAH may have disclosed the unprecedented flexibility and expandability of the atrial appendage in children.