A cardiac hemangioma consists of vascular malformations, which are composed of numerous endothelial-lined thin-walled channels with interspersed fat and fibrous septa. It is usually found in asymptomatic patients. However, due to absence of a location predilection, clinical symptoms can present according to location and size of the tumor. Surgical treatment for symptomatic patients is recommended, since prognosis after excision is excellent.

Epidemiology
Cardiac hemangiomas are rare, benign lesions with an incidence of 1–10% among all detected benign heart tumors.

Associations
Cardiac hemangiomas can occur in the clinical setting of Kasabach-Merritt syndrome, which is characterized by multiple systemic hemangiomas associated with recurrent thrombocytopenia and consumptive coagulopathy.

Clinical presentation
Mostly, cardiac hemangiomas are asymptomatic. However, they may cause pericardial effusion, asymptomatic murmur, arrhythmias, hemopericardium or cardiac tamponade, complete heart block or even sudden death. In addition, these tumors have been incriminated for neurological manifestations.

Pathology
These vascular malformations are composed of numerous endothelial-lined thin-walled channels with interspersed fat and fibrous septa. Histological classification is according to the size of their vascular channels into three types: capillary (composed of smaller capillary-like vessels), cavernous (composed of multiple thin-walled, dilated vessels), and arteriovenous (composed of thick-walled dysplastic arteries, venous-like vessels, and capillaries). Cavernous and capillary hemangiomas are the most frequently reported forms, whereas a combination of all three features also is commonly seen, as well as fibrous and fatty components.

Location
Cardiac hemangioma has been reported to occur in variable locations of the heart involving any cardiac layer, namely endo-, myo-, or pericardium. The left atrium has previously been suggested as the predominant location for cardiac tumors. However, recent evidence has shown no chamber predilection. Hence, occurrence is possible anywhere from pericardium to endocardium.

Radiographic features

Ultrasound/echocardiography
On echocardiography, hemangiomas appear hyperechoic.

Angiography
Coronary arteriography demonstrates the blood supply to the tumor, which is characterized by a vascular blush, particularly in the capillary and arteriovenous types of hemangiomas, which exhibit rapid blood flow. Cavernous hemangiomas have large vascular spaces with very slow flow and therefore do not typically enhance at angiography ⁸.

CT
Heterogeneous appearance on unenhanced chest CT, and, in most cases, intensely enhanced at CT performed after contrast material administration. Foci of calcification may also be seen be seen ⁸.

MRI
Hemangioma is seen as a heterogeneous mass, with intermediate-to-high signal on T1-weighted images because of slow flow. On T2-weighted images, a diffusely high signal is seen. Contrast enhancement is heterogeneous, intense and prolonged except in low-flow lesions.
Potential complications

• development of cardiac arrhythmias
• intracavitary growth may cause
  • ventricular outflow tract obstruction
  • valvular compromise
  • disruption of intracardiac blood flow leading to congestive heart failure and hydrops

Treatment and prognosis
Cardiac hemangiomas may be successfully excised, and surgical resection is the treatment of choice for symptomatic lesions or when diagnosis is in question. The long-term outcome of patients with surgically-treated symptomatic lesions is excellent. Spontaneous regression of a cardiac hemangioma has been reported, and, therefore, surgery may not always be necessary, particularly for extensive but asymptomatic hemangiomas that would require complex and potentially hazardous excision.

Differential diagnosis
Differentiation from malignancies and thrombus is very important, since it greatly affects prognosis and necessity of (acute) treatment.
Differential diagnosis:

• thrombus
• primary benign tumor
  • myxoma
  • fibroelastoma
  • lipoma
  • paraganglioma
  • fibroma
• primary malignant tumor
  • sarcoma
  • lymphoma
  • malignant fibrous histiocytoma
  • pericardial malignancy
• metastasis