Endomyocardial fibroelastosis is a cause of unexplained childhood cardiac insufficiency. It results from diffuse thickening of the endocardium leading to dilated myocardiopathy in the majority of cases and restrictive myocardiopathy in rare cases. It may occur as a primary disorder or may be secondary to another cardiac malformation, notably aortic stenosis or atresia.

A connective tissue neoplasm formed by proliferation of mesodermal cells. Bone and soft tissue sarcomas are the main types of sarcoma. Sarcoma is usually highly malignant.