Bone marrow observed in radiofrequency ablation scar tissue.

摘要

A 60-year-old woman was admitted with congestive heart failure due to paroxysmal atrial fibrillation and flutter. She had been diagnosed with multiple myeloma (IgG, kappa) as well as the heart condition 3 years prior. The surface electrocardiogram showed an atypical atrial flutter with positive F wave in II, III, aVF lead. The electrophysiologic study was performed and entrained with pacing from the coronary sinus ostium. To terminate the atrial flutter, radiofrequency (RF) current was delivered along the inferior vena cava- and coronary sinus ostium-tricuspid valve isthmus (inferior andseptal isthmus) at 60 degrees. The patient died unexpectedly 1 year later. Autopsy showed dilatation and wall thickening of all chambers of the heart. Histologically, severe interstitial fibrosis was observed in both the atria and the ventriculi. Red-orange amyloid deposits were revealed in the intermyocardialarteriole by Congo-red and diagnosed with cardiac amyloidosis. At the ablative lesion, two gray-white nodules were observed next to the edge of the coronary sinus ostium. Histologically, diffuse fibrosis and diffuse cartilage metaplasia were observed within the inferior and septal isthmuses. In the subendocardial nodules, calcium deposits with bone marrow tissue were noted (Figure 1, allows, azan-Mallory stain, bar = 1 mm, CS = coronary sinus, MV = mitral valve, TV = tricuspid valve, VS = ventricular septum). This bone marrow tissue contained regular three hematopoietic components (granulocytes, erythrocytes, and megakaryocytes) (inset figure, hematoxylin-eosin stain, bar = 20 mum). Bone marrow arising after osseous metaplasia within the myocardium is rare.