Primary Benign, Malignant, and Metastatic Tumors of the Heart

Cardiac masses are often the subject of case reports because of their rarity. However, because they are so infrequent, they often challenge the diagnostic skills of even the most experienced physician. Improvements in echocardiography, including real-time three-dimensional (3D) echocardiography, as well as cardiac computed tomography (CT) and cardiac magnetic resonance imaging (CMRI), have enabled cardiologists to better refine the differential diagnosis of cardiac masses.

Cardiac masses are generally first noted antemortem with echocardiography. The sensitivity and specificity of echocardiography for the detection of cardiac masses is difficult to precisely discern because the incidence of cardiac tumors is low, especially for primary tumors. Data from several small case series, however, offer some insight about the diagnostic yield from two-dimensional (2D) echocardiography. For instance, the sensitivity of 2D transthoracic echocardiography for the detection of a pathologically confirmed tumor was 93.3% with a minimal detectable tumor size of 0.5 to 1.0 cm ² in one series of 149 patients. In the same series, 2D transesophageal echocardiography (TEE) had a sensitivity of 96.8%.

Three-dimensional echocardiography appears to have incremental yield when used as an adjunct to 2D echocardiography. Its value lies in its ability to provide additional information about the location of a mass, its size, site of attachment, and potential approach for surgical resection. In one series, 3D TEE provided incremental information over 2D echocardiography for the preoperative assessment of 37% of the patients studied and was estimated to be able to do so in approximately 18% of all intracardiac masses. Another way in which 3D echocardiography may be helpful is in determining the size of a cardiac mass. Compared with real-time 3D echocardiography, 2D transthoracic echocardiography has been shown to underestimate the diameter of cardiac masses by as much as 24.6%. Similarly, 2D TEE can underestimate mass diameter by 19.8% compared with real-time 3D echocardiography. This has clinical importance because the diameter of a mass, whether it is a vegetation, thrombus, or tumor, has important implications for patient prognosis and embolic potential. Advanced cardiac imaging is now more readily available for diagnostic evaluation of cardiac masses. CMRI is the most commonly used imaging modality after echocardiography; at present, cardiac CT has a more limited role.

Tumor Classification and Frequency

Cardiac masses can be classified as primary or secondary, benign or malignant, or by their location: atrial, ventricular, or valvular. Tables 125.1 and 125.2 show the relative frequencies of primary benign, primary malignant, and metastatic neoplasms. Fig. 125.1 illustrates how the location of a mass may provide a helpful clue to its cause.

TABLE 125.1

Armed Forces Institute of Pathology 1976 to 1993 Report on the Most Common Primary Benign and Malignant Tumors of the Heart

Modified from Burke A, Virmani R: Atlas of Tumor Pathology. Tumors of the Heart and Great Vessels . Washington, DC: Armed Forces Institute of Pathology 1996:231.

Tumor	Total	Surgical	Autopsy	Age 15 Years or Younger at Diagnosis
Primary Benign Neoplasms of the Heart
Myxoma	114	102	12	4
Rhabdomyoma	20	6	14	20
Fibroma	20	18	2	13
Hemangioma	17	10	7	2
Atrioventricular nodal	10	0	10	2
Granular cell	4	0	4	0
Lipoma	2	2	0	0
Paraganglioma	2	2	0	0
Myocytic hamartoma	2	2	0	0
Histiocytoid cardiomyopathy	2	0	2	2
Inflammatory pseudotumor	2	2	0	1
Fibrous histiocytoma	1	0	1	0
Epithelioid hemangioendothelioma	1	1	0	0
Bronchogenic cyst	1	1	0	0
Teratoma	1	0	1	1
Totals	199	146 (73%)	53 (27%)	45 (23%)
Primary Malignant Tumors of the Heart
Sarcoma	137 (95%)	116	21	11 (8%)
Angioma	33	22	11	1
Unclassified	33	30	3	3
Fibrous histiocytoma	16	16	0	1
Osteoma	13	13	0	0
Leiomyoma	12	11	1	1
Fibroma	9	9	0	1
Myxoma	8	8	0	1
Rhabdomyoma	6	2	4	3
Synovial	4	4	0	0
Lipoma	2	0	2	0
Schwannoma	1	1	0	0
Lymphoma	7 (5%)	1	6	0
Totals	144	117 (81%)	27 (19%)	11 (8%)

TABLE 125.2

Metastatic Neoplasms of the Heart at Necropsy: Order of Frequency of Cancers Encountered ^a

Modified from Burke A, Virmani R: Tumors of the Cardiovascular System. Atlas of Tumor Pathology . Washington, DC: Armed Forces Institute of Pathology 1996:231; and Mukai K, et al: The incidence of secondary tumors of the heart and pericardium: a 10-year study, Jpn N Clin Oncol 18:195-201, 1988.

Primary Tumor	Total Autopsies	Metastases to the Heart
Lung	1037	180 (17%)
Breast	685	70 (10%)
Lymphoma	392	67 (17%)
Leukemia	202	66 (33%)
Esophagus	294	37 (13%)
Uterus	451	36 (8%)
Melanoma	69	32 (46%)
Stomach	603	28 (5%)
Sarcoma	159	24 (15%)
Oral cavity and tongue	235	22 (9%)
Colon and rectum	440	22 (5%)
Kidney	114	12 (11%)
Thyroid gland	97	9 (9%)
Larynx	100	9 (9%)
Germ cell	21	8 (38%)
Urinary bladder	128	8 (6%)
Liver and biliary tract	325	7 (2%)
Prostate gland	171	6 (4%)
Pancreas	185	6 (3%)
Ovary	188	2 (1%)
Nose (interior)	32	1 (3%)
Pharynx	67	1 (1%)
Miscellaneous	245	0
Total	6240	653 (10%)

a In this series including some of the more commonly encountered malignancies, melanoma is the primary tumor for which metastatic tumors were most commonly found in the heart on autopsy.