Abstract
A case of chylopericardium associated with lymphangiomatous malformation of the thymus is presented. The specific diagnosis of chylopericardium was made by pericardiocentesis and analysis of the fluid. Despite the pericardiocentesis and pericardial tube drainage, pericardial effusion recurred and the patient underwent pericardiectomy. At operation the thymus, which contained a tumor and showed diffuse hyperplasia, was excised and pericardiectomy was performed. The 2-year-old patient recovered uneventfully without reaccumulation of the chyle. The pathologic diagnosis of the mass was intrathymic ectatic lymphangiomatous malformation.