CT OF CALCIFIED CHRONIC AORTIC DISSECTION SIMULATING ATHEROSCLEROTIC ANEURYSM

Calcification along the outermost aspect of the aorta usually means at herosclerotic aneurysm. On occasion, however, this peripheral type cal cification is seen in chronic aortic dissection and leads to a misdiag nosis. Conventional chest roentgenography and CT of 50 cases of chroni c dissection proven by angiography were reviewed. Four of these cases (8%) showed calcification in the outermost wall of the affected portio n of the aorta. Two cases were Stanford type A and the other two cases were type B. In type A cases chest roentgenography showed calcificati on in the wall of the dilated ascending aorta closely mimicking aneury sm. In type B cases, calcification was in the outer wall of a localize d hump in the descending aorta. Computed tomography clearly demonstrat ed that this peripheral calcification was located in the outermost wal l of the false lumen. Review of the pathologic literature shows sporad ic reports of such phenomenon and a theory of endothelialization of th e false lumen. It is presumed that the endothelialized false lumen may develop atheromatous changes much more rapidly than the true lumen si nce two of four cases showed calcification only in the wall of the fal se lumen with the intimal flap and the wall of the true lumen remainin g noncalcified.