Mogul signs are various bumps or moguls seen on the cardiac borders on chest X-ray. Moguls are bumps formed on ski paths as skiers push snow into mounds as they take sharp turns. The mogul signs seen on the left cardiac border are:
First mogul: Aortic knuckle.
Second mogul: Main pulmonary artery segment when it is dilated.
Third mogul: Prominent left atrial appendage or other structures in same location like a submitral aneurysm, dilated right ventricular outflow tract or a pericardial cyst.
Fourth mogul: Cardiac apex
Fifth mogul: Prominent pericardial pad of fat or pericardial cyst at the left cardiophrenic angle.
Right sided mogul is usually an enlarged right atrial border. One of the earliest references on mogul signs was from Daves ML in 1970 . This article has been cited in Chest .
A mogul can form due to left ventricular pseudoaneurysm after mitral valve replacement . Early recognition of this is important as pseudoaneurysms are prone for rupture with catastrophic results.
In addition to the mogul signs, the chest X-ray shows prominent upper lobe vessels (antler sign) and double atrial shadow or shadow within shadow of left atrial enlargement. The left atrial shadow is seen as a double density within the right atrial shadow as part of the enlarged left atrium extends posterior to the right atrium. All these features are suggestive of mitral stenosis with pulmonary hypertension.
Daves ML. Skiagraphing the mediastinal moguls. New Physician. 1970. 19:49-54.