An intramyocardial ‘cyst-like’ mass: Complementary role of multimodality imaging

A 28-year-old female who had been diagnosed with Kawasaki disease at the age of 5, presented to our clinic with the complaint of shortness of breath on exertion. The ECG showed 0.5 mm ST depression and negative T waves in V2-V4 derivations (Fig. 1). Two-dimensional transthoracic echocardiography revealed normal left ventricle dimensions with an ejection fraction of 60%. There was a unilocular, cystic, hypointense, sharply marginated mass measuring 23x15 mm in the interventricular septum (Fig. 2). A cardiac MRI demonstrated a cystic massive structure of approximately 27x17 mm in dimensions with no contrast uptake (Fig. 3). The patient underwent open heart surgery, which showed a large diameter circumflex artery merging with an aneurysmatic vascular structure penetrating into the myocardium along the left anterior descendant (LAD) artery trace of the anterior cardiac surface through apex. An arteriotomy was performed in a small area of the aneurysmatic vascular structure, and the arterial wall was resected about 4x4 mm for pathological analysis. Microscopic examination showed fibrosis, reactive proliferative and infiltrative changes in the vascular section, and advanced coronary vasculitis (Fig. 4). Coronary angiography could not be performed because of patient refusal. In order to identify the coronary anatomy, a multidetector-row computed tomography. Volume rendering images showed that the distal segment of LAD took course inside the interventricular septum, the circumflex artery ran down towards the apex on the anterolateral wall of the left ventricule after leaving the left main coronary artery, and following bifurcation at the apex united again after a short course; later dividing into two branches. One ran down to the interventricular groove, and the other penetrated into the interventricular septum; resulting in an intraseptal thrombosed aneurysmatic segment of 22 x 33 x 46 mm. There were also small branches reaching this aneurysmatic segment from the intraseptal portion of the LAD (Fig. 5). The patient was started on an anti-ischemic treatment protocol upon discharge.