Multifocal myocardial necrosis: a distinctive cardiac lesion in cystic fibrosis, lipomatous pancreatic atrophy, and Keshan disease.

Multifocal myocardial necrosis (MMN) is an unusual cardiomyopathy of childhood, characterized by multiple patchy areas of myocardial fiber necrosis/fibrosis involving mainly the middle part of the left ventricle, but also, to a lesser extent, the right ventricle and the atria. These necrotic lesions are isolated and are not accompanied by an inflammatory reaction or vascular alterations. They are responsible for acute cardiac failure. MMN lesions are observed in various pathologic conditions including cystic fibrosis of the pancreas, pancreatic lipomatous hypoplasia/atrophy, malnutrition due to extensive intestinal resection with subsequent total parenteral feeding, and in Keshan disease. MMN is the main and the most characteristic feature of Keshan disease, an endemic and idiopathic condition affecting Chinese rural children. The causes and mechanisms of MMN presently are unknown. However, the presence of similar cardiac lesions in such different pathological conditions suggests the role of a selective deficiency of a hypothetical extrinsic factor (selenium, molybdenum iodide, other), probably crucial for the metabolism of the myocardial fiber.