RESUMO
Intramyocardial cartilage has never been reported in the human heart before. In the literature, the only reported localizations of cartilage in the heart were in the central fibrous body and the valves. We report a case of an unusual presence of cartilage tissue within the myocardial wall of the left ventricle in a 10-year-old boy who died unexpectedly. This case presents an interesting, unusual and apparently asymptomatic sudden cardiac death related to a cartilaginous myocardial tumor. Conducting system disturbance secondary to the myocardial tumor is the probable cause of death. This case is relevant not only for its singularity and originality, but also for the diverse and controversial hypotheses related to the onset of cartilaginous tissue in the myocardial wall. Early detection of this tumor by modern thoracic imaging may have prevented a fatal unexpected outcome.