Pathologic Quiz Case: An Exceedingly Rare Cause of Sudden Cardiac Death

A 7-year-old African American boy suddenly collapsed while eating at home. Resuscitation efforts consisted of advanced cardiac life support, including cardiac defibrillation, but were unsuccessful. His medical history was contributory for sickle cell anemia and repair several years earlier of an aortic coarctation secondary to Shone syndrome, consisting of coarctation of aorta, parachute deformity of mitral valve, aortic stenosis, and persistent left subclavian vein. Yearly pediatric cardiology follow-up examinations showed no symptoms of heart disease and a normally active child. Several color-flow Doppler echocardiograms showed a 2.0 × 1.0-cm density in the atrial septum, present since infancy, but now changing in contrast. The density was thought to be a benign atrial septal aneurysm that was clinically of no consequence. The patient was doing well and had not been hospitalized for 5 years before presentation to the medical examiner. A complete autopsy was performed.At autopsy, the heart was longitudinally sectioned through the left atrium and left ventricle. This revealed a nodule at the atrioventricular (AV) node of the otherwise normal, smooth, white left atrial wall (Figure 1). Serial sections through the nodule revealed a 1.3 × 1.1 × 1.0-cm, tan mass in the wall of the left atrium at the AV node, which appeared to have numerous vascular channels (Figure 2). A section of the AV node mass was stained with elastic van Gieson and counterstained with Gomori trichrome stain (original magnification ×200, Figure 3), which highlighted cardiac myocytes at the AV node interrupted by numerous, large, irregular vascular channels, many of which had fragmented parallel lamellae of elastic tissue and an endothelial lining. Lymphocytic change in the myocardium was present nearby.The diagnosis of primary cardiac hemangioma was based on clearly identifiable vascular structures interrupting the conduction pathway of the heart in the absence of necrosis, mitotic figures, cellular pleomorphism, and the cellularity of malignant neoplasms. Cardiac hemangioma is rarely misdiagnosed based on histology.Tumors of the heart are rarely encountered, the most common being atrial myxoma in an adult. The most common childhood primary cardiac tumors in order of decreasing frequency are rhabdomyoma, fibroma, and myxoma.1 The incidence of primary cardiac tumors at autopsy is 1 per 10 000 in patients of all ages, and far less common in infants and children.2 Metastatic lesions of the heart occur 20 to 40 times more frequently. One of the rare primary cardiac tumors, hemangiomas are vascular tumors composed of blood vessels that can be either capillaries (capillary hemangioma) or large cavernous vascular channels (cavernous hemangioma). Any organ can be involved, but most frequently hemangiomas are localized to the skin and subcutaneous tissues. Localization to the heart is extremely rare. Hemangiomas composed of dilated structures that occur in the atrial septum have been separately classified as venous malformations.3 A review of 145 primary cardiac tumors of all types at the Armed Forces Institute of Pathology showed 34 cases (23%) causing sudden death. Six of these cases of sudden death were due to cardiac hemangiomas, and to my knowledge, these cases are the only ones ever reported in the world literature.4 Using data obtained from the Centers for Disease Control and Prevention, only 0.0004% of all sudden deaths are due to primary cardiac hemangiomas. Owing to the rarity of these lesions, it seems likely that many practicing autopsy pathologists will never encounter a cardiac hemangioma.4Cardiac hemangiomas occur in patients of all ages, from 4 months to the seventh decade of life, and there is a male predominance of nearly 2 to 1.3 The most common sites are multiple (30%), lateral wall of the left ventricle (21%), anterior wall of the right ventricle (21%), and septal involvement (17%).5 The hemangiomas causing sudden death generally cause conduction disturbances and are located in the region of the AV node or in the ventricles.3,5On rare occasions, this tumor can cause cardiac tamponade, resulting in sudden death.6 Recent advances in cardiac catheterization, cineangiography, and cardiac surgery have placed a burden on the physician to detect primary cardiac tumors antemortem.2 Doppler echocardiography constitutes the first step of the workup and allows the diagnosis of cardiac tumor. The next step should be contrast-enhanced computed tomographic scanning or magnetic resonance imaging.5 In most cases, a cardiac surgeon can completely excise the tumor; however, both spontaneous remission and remission after steroid therapy have been reported.