Morgagni hernias are more frequently encountered on the right side. The diaphragmatic defect and epiploic vessels confirm this diagnosis instead of a fat pad. They are a lot rarer than Bochdaleck (posterior) hernia. This case is particularly interesting since the fat density on plain film mimics a cardiomegaly.
Extensive pericardial lipomatosis, lipoma or extensive pericardial fat pad (e.g. in a patient with Cushing's syndrome) are the most important differential diagnosis in this case.