Cardiac Tumors

Avirup Guha

Abdallah Mughrabi

Zeeshan Hussain

INTRODUCTION

Cardiac masses are rare but critical entities that may involve the endocardium, myocardium, epicardium, and/or pericardium. These include benign tumors, malignant tumors (primary and secondary), and tumor-like conditions (eg, thrombus, Lambl excrescences [LEs], pericardial cyst [PCs]). Similarities in clinical and radiologic features often result in confusion and misdiagnosis. In an effort to help the clinician develop a reliable approach to such entities, this chapter reviews the epidemiology, clinical presentation, imaging, diagnosis, management, and outcome of cardiac masses.

Cardiac tumors are rare neoplasms involving the heart classified into primary and secondary tumors (ie, metastasis to the heart). Primary cardiac tumors (PCTs) are extremely rare and originate from the pericardium, myocardium, or endocardium. The incidence of clinically diagnosed PCTs is 1380 per 100 million individuals, of which 5% to 6% are malignant.¹,² Compared to PCTs, secondary cardiac tumors (SCTs) are 132 times more common.³ Over the past few decades, a notable increase in the incidence of PCTs was shown.¹,⁴

PCTs are classified into three main classes: benign, malignant, and intermediate with uncertain biologic behavior.⁵ The latter class was newly featured in the 2015 World Health Organization (WHO) classification (Table 24.1).⁶ Benign etiologies comprise the majority of all primary tumors (more than 90%), whereas less than 10% are malignant and only 1% are intermediate.⁴,⁷,⁸ It is shown that different pathologic subtypes have anatomic predilection for specific cardiac locations (Figure 24.1), with most cases to be found in the left atrium.⁸

BENIGN PRIMARY CARDIAC TUMORS

Benign PCTs are relatively more prevalent among all PCTs and have a predilection for older females.⁷,⁸ Histopathologic subtypes include myxoma, rhabdomyoma, papillary fibroelastoma, fibroma, hemangioma, lipoma, and leiomyoma. Myxoma is by far the predominant pathologic subtype.⁷ Non-myxoma subtypes, which mostly occur in children and adolescents, are less reported.⁴,⁷,⁸ Benign tumors exhibit favorable prognosis, with 30-day mortality of only 1%.⁷

Clinical Presentation of Benign Primary Cardiac Tumors

According to their size and location, benign PCTs manifest with a wide array of symptoms. Blood flow obstruction can result in dyspnea, chest pain, and palpitations. Thromboembolic complications, mostly cerebral, are found in approximately 10% of patients. Incidental detection is in 13.3% to 27.7% of cases. Affected individuals may also remain asymptomatic.⁴,⁷

Cardiac Myxoma

Cardiac myxoma is the most common PCT.⁷ Myxoma is primarily a left atrial mass arising from the septum. Atrial free wall and mitral valve leaflets are less likely anatomic origins.⁴ Association with Carney complex is well established.⁹ Nonetheless, most cardiac myxomas are sporadic.¹⁰

Myxomas are morphologically classified into polypoid and papillary (Figure 24.1). The former, when large, may present with obstructive symptoms, with a “tumor plop” being occasionally heard on auscultation. By contrast, papillary myxoma tends to cause embolic events. In both variants, constitutional symptoms like fatigue, fever, and weight loss are also reported.¹⁰

Papillary Fibroelastoma

Papillary fibroelastoma (PF) is a rarer tumor comprising only 11.5% of PCTs.⁷ Patients are typically middle-aged presenting with embolic complications, particularly cerebral. This is due to the tumor’s predilection for left-sided valves.¹¹

Rhabdomyoma and Fibroma

Rhabdomyoma is the most prevalent pediatric PCT and typically presents during the first year of life.¹² Rhabdomyomas are arrhythmogenic, but cavitary protrusion with resulting flow obstruction is also seen.¹² Association with tuberous sclerosis is well established.¹² Cardiac fibroma is the second most common PCT in infants.¹² Similarly, involvement of the interventricular septum and left ventricular free wall is typical.⁹ Consequently, arrhythmias and flow obstruction result.¹²

Rare Primary Cardiac Tumors—Hemangiomas, Lipomas, Leiomyomas

Rarer PCTs include hemangiomas, lipomas, and leiomyomas. Hemangioma may involve any chamber.⁴ When larger than a few centimeters, it can cause obstructive symptoms. Cardiac lipomas are often seen in individuals between their fourth and seventh decade.⁴ These tumors may also involve any chamber and are mostly asymptomatic. When large, they may impede blood flow.⁴ Primary cardiac leiomyomas

are exceedingly rare tumors, described only in a handful of cases.¹³ Consequently, this entity is not listed in the WHO classification.⁶ Those tumors are derived from smooth muscles and exhibit white, whorled, and firm appearance (Figure 24.1).¹³

TABLE 24.1 The 2015 WHO Classification of Cardiac Tumors with Associated Incidence, Survival and Outcome

Class	Subtype and References	Subtype (%) of Class^a	Outcome/Survival
Benign tumors (and tumor-like conditions) Incidence rate/year: 1.24/100,000 individuals^e Mean survival (months): 187.2 ± 2.7	Cardiac myxoma⁴,⁷,¹⁰,¹²,¹⁸,¹⁹	76.5%-93%^b	Surgical therapy is definitive with low likelihood of recurrence (1%-5.4%).
	Papillary fibroelastoma⁷,²⁰	13%^b	Surgical resection is curative with minimal risk/recurrence.
	Rhabdomyoma⁵,¹²	Most common in children	Spontaneous regression in most cases. Postresection relapse: 2.6%.
	Cardiac fibroma¹²,¹⁹	Second most common in children	Surgical resection is curative. Postresection relapse: 1.6%.
	Hemangioma, NOS Capillary hemangioma Cavernous hemangioma Arteriovenous malformation Intramuscular hemangioma⁷,¹⁹	2%^b	In patients with resectable tumors, surgery is recommended and results in good prognosis.
	Lipoma⁴,⁷,⁶³	1%-2%^b	Surgical resection is curative but carries risk, particularly in cases with hemodynamic complications.
	Hamartoma of mature cardiac myocytes⁷	2%^b	Mean survival: 68.5 ± 48.4 months
	Schwannoma⁴	0.5%^b	–
Tumors of uncertain biologic behavior	Inflammatory myofibroblastic tumor	–	–
Tumors of uncertain biologic behavior	Paraganglioma⁴,⁷	0.5%-1%^b	–
Germ cell tumors	Teratoma, mature¹⁴,⁵⁰,⁵³	1%^b	Postresection relapse in 3.4% of cases.
	Teratoma, immature⁴,¹²	1%^b	Postresection relapse in 3.4% of cases.
	Yolk sac tumor	–	–
Malignant tumor Incidence rate^c/year: 0.000894^d-0.24^e/100,000 Mean survival (months): 26.2 ± 9.8 Median survival (months): 10 (25th, 75th percentiles, 1, 29 months)	Angiosarcoma¹,⁴,⁷,³¹,³⁶	8%-29%^f	Median overall survival for all sarcomas: 17.2 months (95% confidence interval 13.5-22.3) Angiosarcoma: Median overall survival: 13 months 5-year survival rate: 8% Leiomyosarcoma: 5-year overall survival is 25.4%. Synovial sarcoma: Median overall survival: 24 months. 5-year overall survival is 29.9%.
	Leiomyosarcoma¹,³⁸	7%^f
	Rhabdomyosarcoma¹	4%^f
	Undifferentiated pleomorphic sarcoma¹,⁴,⁷	9%-25%^f
	Myxofibrosarcoma⁴,⁷	17%-18%^f
	Synovial sarcoma¹,⁷,³⁹,⁶⁸	2%-9% ^f
	Osteosarcoma	–
	Miscellaneous sarcomas¹,⁴,⁷	8%-9%^f
	Cardiac lymphomas¹,⁴,⁷	9%-42%^f	Median survival: 23 months (25th, 75th percentiles, 5, 120 months) 5-year survival is 38% in the past decade.
	Metastatic tumors⁴,⁴⁶	1%-3.5% of all autopsies	Poor survival, determined by the primary malignancy.
Tumors of the pericardium	Malignant mesothelioma^g,¹,⁵⁰,⁵¹,⁵⁵	2%-8%^f	Median survival: 2-6 months 5-year survival rates: 9%
	Angiosarcoma^g,³¹,³⁶	See above	See above
	Synovial sarcoma¹,⁷,³⁹,⁶⁸	See above	See above
	Solitary fibrous tumor Malignant	–	–
	Germ cell tumors¹⁴,⁵⁰,⁵³ Teratoma, mature Teratoma, immature Yolk sac tumor	See above	See above
NOS: Not Otherwise Specified
^aRounded number for simplicity. ^bCalculated percentage is among all benign tumors including germ cell tumors and paragangliomas. ^cExcluding metastatic tumors, but including pericardial tumors. ^dCalculated incidence rate derived from a population study from 1973 through 2011.¹ ^ePopulation study from 1998 through 2011.² ^fCalculated percentage includes pericardial and intracardiac malignant tumors and is among malignant masses including pericardial and intracardial tumors. Metastatic cardiac tumors are excluded. ^gMesotheliomas comprise most of the cases of malignant pericardial tumors followed by pericardial angiosarcomas.⁵¹,⁵²,⁵⁶
Non-exhaustive list.
Adapted with permission from Burke A, Tavora F. The 2015 WHO Classification of Tumors of the Heart and Pericardium. J Thorac Oncol. 2016;11(4):441-452. Copyright © 2016 Elsevier and Travis WD, Brambilla E, Burke A, et al. WHO classification of tumours of the lung, pleura, thymus and heart. International Agency for Research on Cancer, 2015.

FIGURE 24.1 Gross appearance of different pathologic subtypes of primary cardiac tumors. Note the predilection for specific anatomic locations. Cardiac myxoma and sarcoma predominantly affect the left atrium. Papillary fibroelastoma affects valve leaflets and papillary muscles. Lipoma may involve any chamber and arises from subendocardium or intramyocardium. Cardiac lymphoma affects the right heart predominantly. Mesothelioma and paraganglioma (not shown) affect the pericardium.

Diagnosis and Imaging of Benign Primary Cardiac Tumors

Echocardiography is a ubiquitous diagnostic tool utilized in several cardiologic settings. Certainly, it remains a cornerstone in the evaluation of a suspected cardiac mass. A cardiac mass
detected on echocardiography requires a vigilant clinician. Simultaneously, awareness of the rarity of cardiac tumors is key in averting overdiagnosis. A mass on echocardiography is predominantly a thrombus or a vegetation. Upon exclusion, a tumor diagnosis may then be pursued.¹⁴ A comprehensive diagnostic approach for cardiac masses has been presented in the review of Mankad and Herrmann ¹⁴ and adapted in Algorithm 24.1.

ALGORITHM 24.1 Diagnostic approach to cardiac masses. IVC, inferior vena cava; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle.

Imaging is often sufficient for presumptive diagnosis (Table 24.2). Individual subtypes of benign PCTs exhibit imaging characteristics that aid in their differentiation by multi-modality imaging such as echocardiography, cardiac computed tomography (CCT), and cardiac magnetic resonance (CMR) (Figures 24.2, 24.3 and 24.4 and

e-Figures 24.1, 24.2, 24.3, 24.4 and 24.5). Challenges, however, arise when certain mass-like conditions need

to be discerned from benign PCTs. Atrial septal aneurysm (ASA) and lipomatous interatrial septal hypertrophy (LISH) both mimic myxomas and—in the case of LISH—lipomas.¹⁴ On echocardiography, ASA exhibits a redundant septal bulging, beyond the interatrial septal plane with synchronous oscillation through the cardiac cycle.¹⁵ LISH spares fossa ovalis and exhibits a bilobed “dumbbell” echocardiographic appearance¹⁵ (

e-Figure 24.6). PF may be confused with a thrombus, vegetation, or LEs. On echocardiography, a solitary mass in the middle part of the valve’s leaflet, with a characteristic shimmering border vibrating independently from neighboring structures, make PF a more likely diagnosis.¹⁴

TABLE 24.2 Radiologic Findings for Benign Primary Cardiac Tumors

	Echocardiography	Cardiac Computed Tomography (CCT)	Cardiac Magnetic Resonance (CMR)
Myxoma⁹,¹⁴,¹⁷	A mobile, heterogeneous or homogeneous mass often with a stalk (Figure 24.2) Two subtypes: Polypoid: Larger, smooth surface, rough cystic core due to hemorrhage or necrosis Papillary: Smaller with villi	Hypodense, possible calcifications. With contrast: filling defects with heterogeneous enhancement (based on presence of necrosis or hemorrhage)	On T1: variable; hemorrhage (increased signal), calcification (decreased signal) On T2: hypointense, especially if the myxoma contains iron With gadolinium: core may be enhanced due to high vascularity, unless thrombosed
Fibroelastoma¹⁴,¹⁷	A small mass, with “shimmering or stippled borders.” Attached to the endocardium. Mobile, not in sync with other cardiac structures (Figure 24.3).	Identification is challenging.	On T1: isointense On T2: hyperintense With late gadolinium study: possible enhancement
Rhabdomyoma⁹,¹⁴,¹⁷	Small, homogeneously echogenic, well-demarcated, pedunculated, or nodular mass. May be multiple (e-Figure 24.1)	Homogeneous, density similar to myocardium	Solid and homogeneous appearance. On T1: similar intensity to myocardium, may be slightly less On T2: hyperintense On GRE: Very low signal contrasting it from surrounding myocardium
Fibroma4,¹⁴,¹⁶,¹⁷	Well-demarcated, non-contractile, hyperechogenic mass in the myocardial wall.	Hypervascular. With contrast: homogeneous or heterogeneous enhancement Central calcifications are common (vs rhabdomyoma).	On T1: similar intensity when compared to skeletal muscles. Hemorrhage (increased signal), calcification (decreased signal) On T2: intensity decreases relative to myocardium With gadolinium: late enhancement is present (e-Figure 24.2)
Hemangioma⁹,¹⁴,¹⁷	Echogenic mass with some echolucencies	Intense enhancement is seen with contrast administration.	On T1 and T2: hyperintense compared to myocardium. First-pass perfusion study with gadolinium: rapid centripetal heterogeneous enhancement (e-Figure 24.3)
Lipoma⁹,¹⁴,¹⁷	Well-circumscribed mass with a wide base limiting its mobility. Intracardiac: hyperechogenic Pericardial: hypoechogenic	Smooth, well-defined, with fat attenuation With contrast: no enhancement	On T1: hyperintense (as subcutaneous fat). Decrease in intensity on “fat presaturation” technique verifies diagnosis. On T2: mild decrease in intensity With gadolinium contrast: no enhancement. (Figure 24.4)
Cardiac leiomyoma¹³,¹⁷	Hyperechogenic mass (e-Figure 24.4)	A well-defined mass with possible calcifications.	Similar signal intensity to myocardium
Mitral annular calcification with caseous necrosis²²,⁶⁴	Large, echogenic and round mass with a central echolucency (e-Figure 24.7)	Calcified ring surrounding a less dense core	On T1: hyperintense center with hypointense periphery On gadolinium study: late enhancement at core and periphery
Intracardiac thrombus¹⁴,¹⁷	Nonenhancing mass on contrast echocardiography and possible wall motion abnormalities	Hypodense (e-Figure 24.5)	On T1: hyperintense On T2: hyperintense Upon aging of thrombus: intensity decreases On gradient recalled echo: lowest intensity compared to surrounding structures. With gadolinium contrast: no enhancement, unless mature organized thrombus
Lambl excrescences¹⁵,²⁸,²⁹	Multiple mobile echogenicities with very thin lint-like appearance often arising from the aortic valvular leaflets (Figure 24.5)	Identification is challenging.	Identification is challenging.
GRE, Gradient Echo Sequences.

FIGURE 24.2 A Transesophageal echocardiogram (TEE) (midesophageal long axis view) revealing a Left atrial (LA) myxoma. (Reprinted with permission from Barash PG, Cullen BF, Stoelting RK, et al. Clinical Anesthesia. 6th ed. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2009. Figure 28.47 View A.)

Pediatric PCTs, namely rhabdomyomas and fibromas, are challenging to distinguish through imaging. Nonetheless, unlike the former, fibroma is typically solitary and centrally calcified.¹⁶ Hemangiomas appear echogenic with interspersed lucencies on echocardiography.¹⁴ Lipomas characteristically demonstrate a decrease in signal intensity after fat presaturation on T1 CMR sequence.¹⁷

FIGURE 24.3 Transesophageal echocardiogram showing a homogeneously echogenic pedunculated mass, measuring 1.5 cm and arising from the aortic valve (papillary fibroelastoma). (Reprinted with permission from Vimalesvaran K, Lumley M, Child N, et al. Recurrent right coronary artery occlusion caused by cardiac fibroelastoma attached to the aortic valve. Circulation. 2015;131(6):593-595. Copyright © 2015 American Heart Association, Inc.)

FIGURE 24.4 Cardiac magnetic resonance (CMR) imaging of a cardiac lipoma. Note the infarcted mass (white arrow) and the associated pericarditis. (Reprinted with permission from Bezuidenhout AF, Ridge CA, Litmanovich D. Lung. In: Lee EY, Hunsaker A, Siewert B, eds. Computed Body Tomography with MRI Correlation. 5th ed. Philadelphia, PA: Wolters Kluwer; 2020:253-398. Figure 6.6.)

Management and Outcome of Benign Primary Cardiac Tumors

Definitive management of benign PCTs is surgical (Table 24.3). Myxomas, hemangiomas, and fibromas should be resected because of the risk of complications including sudden cardiac death.¹⁸,¹⁹ Unlike fibromas, most
rhabdomyomas regress spontaneously, but surgical removal should be considered once complications arise.⁵ Large or symptomatic lipomas and leiomyomas require excision.¹³,¹⁹ Similarly, symptomatic PFs require surgical intervention.¹⁹,²⁰,²¹ Asymptomatic patients with large (>1 cm) or mobile PFs may also be surgical candidates whereas nonmobile, small, and asymptomatic lesions are managed with anticoagulants and followed up.²⁰,²¹

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May 8, 2022 | Posted by drzezo in CARDIOLOGY | Comments Off

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