Hallazgo de una hiperplasia lipomatosa del septum interauricular en un caso de muerte súbita

the lipomatous hyperplasia of the interatrial septum (lhis) is a benign entity of unknown nature, characterized by the accumulation of fat tissue not encapsulated into the interatrial groove without participation of the fossa ovalis. despite its benign nature, it has been clinically associated with cardiac arrhythmias, usually of supraventricular origin, heart failure and sudden death. we present the case of a woman of middle age (47 years), with morbid obesity and heart failure congestive who died suddenly and the autopsy revealed a lhis. the macroscopic study of resection piece showed a size of 5 x 2.5 cm and the typical histology of this entity, i.e. mature adipocytes and few lipoblastos interspersed with atrial myocytes. we have analysed microscopically both sinoatrial and atrioventricular nodes, which they revealed fat tissue infiltration that surrounded them but not isolated from atrial working myocardium. the interventricular septum and left ventricle myocardium presented areas with severe interstitial fibrosis by chronic ischemic and this fibrosis may be the cause of ventricular arrhythmia and sudden death. although this entity is most frequently recognized due to the development of noninvasive imaging techniques, rarely needs to be corrected surgically.